PRIME MEDICAL SERVICES INC /TX/
10-K, 2000-03-30
MISC HEALTH & ALLIED SERVICES, NEC
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                                  UNITED STATES

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549


                                    FORM 10-K

              [X] Annual Report Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934
                   For the fiscal year ended December 31, 1999

            [ ] Transition Report Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934

                         For the transition period from

                                 _____ to _____

                         Commission File Number: 0-22392

                           -------------------------
                          PRIME MEDICAL SERVICES, INC.
             (Exact name of registrant as specified in its charter)

         DELAWARE                                                74-2652727
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization                               Identification No.)

               1301 Capital of Texas Highway, Austin, Texas 78746
               (Address of principal executive offices) (Zip Code)

                                 (512) 328-2892
              (Registrant's telephone number, including area code)

     Check whether the issuer (1) has filed all reports  required to be filed by
Section 13 or 15(d) of the Securities  Exchange Act of 1934 during the preceding
12 months (or for such shorter  period that the  registrant was required to file
such reports), and (2) has been subject to such filing requirements for the past
90 days. YES X NO
            ---   ---

     Check if there is no disclosure  of  delinquent  filers in response to Item
405 of  Regulation  S-K  contained  in  this  form,  and no  disclosure  will be
contained,  to the best of the  registrant's  knowledge,  in definitive proxy or
information statements incorporated by reference in Part III of the Form 10-K or
any amendment to this Form 10-K. _____

     State the aggregate market value of the voting stock held by non-affiliates
computed by reference  to the price at which the stock was sold,  or the average
bid and asked prices of such stock,  as of a specified date within 60 days prior
to the date of filing.

             Aggregate Market Value at March 15, 2000: $140,420,073

     Indicate the number of shares  outstanding of each of the issuer's  classes
of common equity, as of the latest practicable date.

                                                Number of Shares Outstanding at

        Title of Each Class                              March 15, 2000
        -------------------                              --------------
    Common Stock, $.01 par value                           16,398,467

                       DOCUMENTS INCORPORATED BY REFERENCE

     Selected  portions of the  Registrant's  definitive  proxy material for the
2000 annual meeting of shareholders  are incorporated by reference into Part III
of the Form 10-K.

                                        1

<PAGE>

                          PRIME MEDICAL SERVICES, INC.,

                           ANNUAL REPORT ON FORM 10-K

                   FOR THE FISCAL YEAR ENDED DECEMBER 31, 1999

                                     PART I

ITEM 1.  BUSINESS
- -------  --------

         Prime Medical Services,  Inc., a Delaware  corporation  ("Prime" or the
"Company"),  is the  largest  provider  of  lithotripsy  services  in the United
States.  Lithotripsy  is a  non-invasive  procedure  for the treatment of kidney
stones, typically performed on an outpatient basis, that eliminates the need for
lengthy hospital stays and extensive  recovery periods  associated with surgery.
The Company has 65  lithotripters of which 59 are mobile and six are fixed site.
The Company's  lithotripters  performed  approximately  38,000 procedures in the
United  States in 1999  through a network of  approximately  450  hospitals  and
surgery centers in 34 states.

         Lithotripters  fragment  kidney stones by use of  extracorporeal  shock
wave lithotripsy.  The Company provides services related to the operation of the
lithotripters,  including  scheduling,  staffing,  training,  quality assurance,
maintenance,  regulatory  compliance and contracting with payors,  hospitals and
surgery  centers.  Medical  care is rendered  by the  urologists  utilizing  the
lithotripters. Management believes that the Company has collected the industry's
largest  and  most  comprehensive  lithotripsy  database,   containing  detailed
treatment and outcomes data on over 160,000 lithotripsy procedures.  The Company
and its  associated  urologists  utilize this database in seeking to provide the
highest quality of lithotripsy services as efficiently as possible.

         From 1992 through 1999, the Company completed 13 acquisitions involving
58  lithotripters.  Since  1992,  the  Company has  substantially  divested  its
original non-lithotripsy businesses.

         During 1997 the  Company  acquired a 75%  interest  in a  manufacturing
company which provides manufacturing  services, and installation,  refurbishment
and repair of major medical equipment for mobile medical services providers. The
primary intention of this acquisition was to provide vertical integration with
the  lithotripsy  business.   However,  the  non-lithotripsy   business  of  the
manufacturing  segment has continued to increase.  In addition to  manufacturing
services for  lithotripsy  trailers,  the  manufacturing  segment also  provides
manufacturing  services  for magnetic  resonance  imaging  ("MRI")  trailers and
cardiac catheterization lab trailers.

         During  1999 the  Company  completed  two  acquisitions  in the rapidly
growing field of refractive  vision  correction  (RVC).  These two  acquisitions
included six laser vision  correction  facilities which performed  approximately
19,000 procedures during 1999. These facilities  provide laser vision correction
of  common  refractive  vision  disorders  such  as  myopia   (nearsightedness),
hyperopia (farsightedness) and astigmatism.

         There are currently two procedures that use the excimer laser ("laser")
to  correct  vision  disorders:   Laser  in-situ  Keratomileusis  ("LASIK")  and
Photorefractive  Keratectomy  ("PRK").  LASIK is an  outpatient  procedure  that
accounts for nearly 90% of laser  procedures done today. In LASIK, an ophthalmic
surgeon uses a special knife called a microkeratome  to peal back the top layers
of the cornea and ablates the  underlying  corneal  tissue with the laser before
replacing  the  corneal  layer.   LASIK  has  three  key  advantages   over  PRK
(photorefractive  keratectomy)  where the  laser is used  without  creating  the
corneal flap: less pain,  shorter  recovery time, and fewer visual side effects.
Patients' enthusiasm and word-of-mouth  referrals for the procedure have been an
important part of LASIK's rapid adoption.

                                        2

<PAGE>

         The Company has three reportable segments:  lithotripsy,  manufacturing
and RVC. Other operating segments,  which do not meet the qualitative thresholds
for  reportable  segments,  include  prostatherapy  services.  See Note N to the
consolidated financial statements for segment disclosures.

Lithotripsy Segment Overview

- ----------------------------

         Kidney stones  develop from crystals made up primarily of calcium which
separate from urine and build up on the inner surfaces of the kidney.  The exact
cause of kidney stone formation is unclear,  and there is no known  preventative
cure in the vast  majority of cases.  Approximately  25% of all kidney stones do
not pass  spontaneously  and therefore  require  medical or surgical  treatment.
Kidney stone treatments used by urologists  include  lithotripsy,  drug therapy,
endoscopic extraction or open surgery. While the nature and location of a kidney
stone impacts the choice of treatment,  the Company believes the majority of all
kidney stones that require treatment are treated with lithotripsy  because it is
non-invasive,  typically  requires no general  anesthesia,  and rarely  requires
hospital stays. After  fragmentation by lithotripsy,  the resulting kidney stone
fragments pass out of the body naturally. Recovery from the procedure is usually
a matter of hours.

         Kidney stone disease is most  prevalent in the southern  United States.
Men are  afflicted  with kidney  stones more than twice as  frequently as women,
with the highest  incidence  occurring in men 45 to 64 years of age. During 1999
the Company  received  approximately  79% of its revenues  from the  lithotripsy
segment.

Kidney Stone Treatment Methods

         A number of kidney stone treatments are used by urologists ranging from
non-invasive  procedures,  such as drug  therapy  or  lithotripsy,  to  invasive
procedures, such as endoscopic extraction or open surgery. The type of treatment
a  urologist  chooses  depends  on a  number  of  factors,  such as the size and
chemical  make-up of the stone,  the stone's  location in the urinary system and
whether  the  stone is  contributing  to  other  urinary  complications  such as
blockage or infection.

         Certain  types of less common  kidney  stones may be dissolved by drugs
which allow normal  passage from the urinary  system.  Stones located in certain
areas of the urinary  tract may be extracted  endoscopically.  These  procedures
commonly  require general or local  anesthesia and can injure the involved areas
of the urinary tract.  Frequently,  kidney stones are located where they are not
accessible by an endoscopic procedure.  Prior to the development of lithotripsy,
stones  lodged in the upper  urinary tract were often treated by open surgery or
percutaneous stone removal,  both major operations requiring an incision to gain
access to the stone. After such procedures, the patient typically spends several
days in the hospital  followed by a convalescence  period of three to six weeks.
As the  technology  for treating  kidney stones has  improved,  there has been a
shift from more expensive and  complicated  invasive  procedures to safer,  more
cost efficient and less painful non-invasive procedures, such as lithotripsy.

Extracorporeal Shock Wave Lithotripsy

         General. The lithotripter has dramatically changed the course of kidney
stone disease treatment since lithotripsy is normally performed on an outpatient
basis, often without general anesthesia. Recovery times are generally only a few
hours,  and most  patients can return to work the next day.  There are two basic
types  of  lithotripsy   treatment  currently  available:   electromagnetic  and
spark-gap. A decision regarding which type is used in any instance may depend on
several factors, among which are the treating physician's preferences, treatment
times,  stone  location,  and  anesthesia  considerations.  The  Company  has 51
electromagnetic machines and 14 spark-gap machines.

                                        3

<PAGE>

         Electromagnetic   Technology.   Most  new   lithotripters   utilize  an
electromagnetic  shock wave  component  that  eliminates the need for disposable
electrodes. The use of lithotripters employing electromagnetic technology allows
for more  precise  focusing  of shock wave  energy and more  predictable  energy
delivery than other  lithotripsy  technologies,  which  eliminates  the need for
anesthesia  in most  cases.  Utilization  of systems  employing  electromagnetic
technology  usually results in  fragmentation  of the kidney stone in between 60
and 90 minutes.

         Spark Gap  Technology.  With these  lithotripsy  systems,  shock  waves
generated by a disposable  high-voltage  spark electrode are focused on a kidney
stone.  Utilization of systems employing spark gap technology usually results in
fragmentation of the kidney stone in less than 60 minutes.  The use of spark-gap
technology  often  requires  the  administration  of  sedatives  or  intravenous
anesthesia care and in some cases requires general anesthesia.

Manufacturing Segment Overview

- ------------------------------

         In  September  1997,  the  Company,  through its  acquisition  of a 75%
interest in AK Associates, L.L.C. ("AK"), began providing manufacturing services
and installation,  upgrade,  refurbishment and repair of major medical equipment
for mobile medical  services  providers.  The Company paid $4.8 million for this
interest,  plus an earn-out of $1.1  million,  which was paid in February  1999.
Certain  members of AK  management  own the  remaining 25% of AK. During 1998 AK
became  certified by General Electric Company ("GE") to provide trailers for MRI
equipment,  and during 1999 AK became  certified by two additional  companies to
provide  trailers for their  equipment.  These  certifications  have resulted in
increased   revenues  in  the  manufacturing   segment.   The  Company  received
approximately 16 % of its revenues from the manufacturing segment in 1999.

RVC Segment Overview

- --------------------

         During  1999,  the  Company  entered  into the RVC  field  through  two
acquisitions.  Effective  September 1, 1999, the Company acquired a 60% interest
in two  refractive  surgery  centers,  owned and operated by Barnet  Dulaney Eye
Center,  for  approximately  $8.8 million in cash, a warrant to purchase  29,000
shares of Company common stock and a contingent  earn-out  obligation to be paid
at the end of the first year of operations  after  acquisition.  Also  effective
September 1, 1999, the Company  acquired,  through a majority owned  subsidiary,
60% of the  outstanding  stock of Horizon Vision Centers,  Inc.  ("Horizon") for
approximately  $10.9 million in cash.  Horizon operates four refractive  surgery
centers.  The Company  received  approximately  3% of its  revenue  from the RVC
segment in 1999.

Refractive Disorders

         The primary  function of the human eye is to focus light. The eye works
much like a camera;  light rays enter the eye through the cornea, which provides
most of the  focusing  power.  Light then  travels  through the lens where it is
fine-tuned to focus properly on the retina.  The retina,  located at the back of
the eye, acts like the film in the camera, changing light into electric impulses
that are carried by the optic nerve to the brain. To see clearly,  light must be
focused precisely on the retina.  The amount of refraction  required to properly
focus images  depends on the curvature of the cornea and the size of the eye. If
the curvature is not correct, the cornea cannot properly focus the light passing
through it onto the retina, and the viewer will see a blurred image.  Refractive
disorders,  such as myopia, hyperopia and astigmatism,  result from an inability
of the cornea and the lens to focus images on the retina properly.

                                        4

<PAGE>

Laser Vision Correction Procedures

         In both PRK and LASIK the  physician  assesses  the corneal  correction
required and  programs the laser.  Using a specially  developed  algorithm,  the
laser's  software  calculates the optimal number of pulses needed to achieve the
corneal  correction.  Both PRK and LASIK are  performed on an  outpatient  basis
without general  anesthesia,  using only topical  anesthetic eye drops.  The eye
drops  eliminate  the reflex to blink,  while an eyelid  holder is  inserted  to
prevent  blinking.  The patient reclines in a chair, with his or her eye focused
on a target,  and the surgeon  positions the patient's cornea for the procedure.
The  surgeon  uses a foot  pedal to apply the laser  beam,  which  emits a rapid
succession of laser pulses. The actual laser treatment takes 15 to 90 seconds to
perform  and the entire  procedure,  from set-up to  completion,  takes 10 to 15
minutes.

Prostatherapy Segment Overview

- ------------------------------

         In October 1997, the Company began providing thermotherapy services for
the treatment of benign prostatic  hyperplasia ("BPH"). BPH is the non-cancerous
enlargement  of  the  prostate,   a  condition   common  in  men  over  age  60.
Thermotherapy uses microwaves to apply heat to the prostate, resulting in relief
of the  symptoms  of BPH without  damaging  surrounding  tissues.  Thermotherapy
relieves the symptoms of BPH without incurring the risks of complications  often
associated with surgery and more invasive procedures. The Company operates three
mobile thermotherapy  devices servicing hospitals and surgery centers in eastern
North Carolina and southern California. The Company is monitoring the success of
its thermotherapy  operations and may expand such operations in the future.  The
Company received approximately 2% of its revenues from the prostatherapy segment
in 1999.

Potential Liabilities-Insurance

- -------------------------------

         All medical  procedures  performed  in  connection  with the  Company's
business  activities  are  conducted  directly by, or under the  supervision  of
physicians,  who are not employees of the Company.  The Company does not provide
medical services to any patients. However, patients being treated at health care
facilities at which the Company provides its non-medical services could suffer a
medical emergency  resulting in serious injury or death, which could subject the
Company to the risk of lawsuits seeking substantial damages.

         The Company  currently  maintains  general and  professional  liability
insurance with a total limit of $1,000,000 per loss event and $3,000,000  policy
aggregate  and an umbrella  excess limit of  $10,000,000,  with a deductible  of
$50,000 per occurrence.  In addition, the Company requires medical professionals
who utilize its services to maintain  professional  liability insurance.  All of
these insurance policies are subject to annual renewal by the insurer.  If these
policies  were to be canceled or not  renewed,  or failed to provide  sufficient
coverage  for  the  Company's  liabilities,  the  Company  might  be  forced  to
self-insure against the potential  liabilities referred to above. In that event,
a single  incident  might  result  in an award of  damages  which  might  have a
material adverse effect on the operations of the Company.

Government Regulation and Supervision

- -------------------------------------

         The  Company is subject to  extensive  regulation  by both the  federal
government  and the  states in which the  Company  conducts  its  business.  The
Company is subject to Section  1128B of the Social  Security  Act (known as "the
Illegal  Remuneration  Statute"),  which imposes civil and criminal sanctions on
persons  who  solicit,  offer,  receive  or pay any  remuneration,  directly  or
indirectly,  for  referring,  or  arranging  for the  referral of, a patient for
treatment that is paid for in whole or in part by Medicare,  Medicaid or similar
government  programs.  The federal  government  has published  regulations  that
provide  exceptions  or a  "safe  harbor"  for  certain  business  transactions.
Transactions that are structured within the safe harbors are deemed not to

                                        5

<PAGE>

violate the Illegal Remuneration  Statute.  Transactions that do not satisfy all
elements  of a relevant  safe  harbor do not  necessarily  violate  the  Illegal
Remuneration  Statute,  but may be subject to greater  scrutiny  by  enforcement
agencies.  The  arrangements  between the Company and the partnerships and other
entities in which it owns an  indirect  interest  and through  which the Company
provides most of its lithotripsy services and all of its prostatherapy  services
(and the corresponding arrangements between such partnerships and other entities
and  the  treating  physicians  who  own  interests  therein  and  who  use  the
lithotripsy and  prostatherapy  facilities owned by such  partnerships and other
entities)  could  potentially  be  questioned  under  the  illegal  remuneration
prohibition  and may not fall  within  the  protection  afforded  by these  safe
harbors.  Many states also have laws similar to the Federal Illegal Remuneration
Statute.  While  failure to fall within the safe harbors may subject the Company
to scrutiny  under the  Illegal  Remuneration  Statute,  such  failure  does not
constitute a violation of the Illegal Remuneration Statute. Nevertheless,  these
illegal remuneration laws, as applied to activities and relationships similar to
those of the Company,  have been  subjected to limited  judicial and  regulatory
interpretation,  and the Company has not  obtained or applied for any opinion of
any  regulatory  or  judicial   authority  that  its  business   operations  and
affiliations are in compliance with these laws. Therefore,  no assurances can be
given that the Company's activities will be found to be in compliance with these
laws if scrutinized by such authorities.

         In addition to the Illegal  Remuneration  Statute,  Section 1877 of the
Social  Security Act ("Stark II") imposes  certain  restrictions  upon referring
physicians  and  providers  of  certain  designated  health  services  under the
Medicare,  Medicaid and Champus  Programs  ("Government  Programs").  Subject to
certain exceptions, Stark II provides that if a physician (or a family member of
a physician) has a financial  relationship with an entity: (i) the physician may
not make a referral  to the  entity  for the  furnishing  of  designated  health
services reimbursable under the Government Programs; and (ii) the entity may not
bill Government Programs, any individual or any third-party payor for designated
health services furnished pursuant to a prohibited referral under the Government
Programs. The prohibitions of Stark II only apply to the treatment of Government
Program   patients,   and  have  no  application   to  services   performed  for
non-government  program patients.  Entities and physicians  committing an act in
violation of Stark II will be required to refund amounts  collected in violation
of the statute and also are subject to civil money  penalties and exclusion from
the  Government  Programs.  Physicians  are  investors in 51 of the Company's 65
lithotripsy  operations,   all  of  the  three  Company  affiliates  engaged  in
thermotherapy   services  and  each  of  the  Company's  six  refractive  vision
correction facilities. The Company lithotripsy and thermotherapy affiliates with
physician-investors are referred to herein as the "Company Physician Entities".

         Many key terms in Stark II are not  adequately  defined and the statute
is silent  regarding its application to vendors,  such as the Company  Physician
Entities,  contracting "'under arrangements" with hospitals for the provision of
outpatient services.  Prior to the publication of the Proposed Stark Regulations
described below, the Company interpreted Stark II consistently with the informal
view of the General  Counsel for Health and Human  Services,  and concluded that
the statute  did not apply to its method of  conducting  business.  Based upon a
reasonable  interpretation  of Stark II, by  referring  a patient  to a hospital
furnishing  the  outpatient   lithotripsy  or   thermotherapy   services  "under
arrangements"  with the Company Physician  Entities,  a physician  investor in a
Company Physician Entity is not making a referral to an entity (the hospital) in
which they have an ownership interest.

         On  January  9,  1998,  the  federal   government   published  proposed
regulations  under Stark II (the "Proposed  Stark  Regulations").  By clarifying
certain  ambiguities and defining  certain  statutory  terms, the Proposed Stark
Regulations   and   accompanying   commentary   apply  the  physician   referral
prohibitions  of  Stark  II to  the  Company  Physician  Entities'  practice  of
contracting  "under  arrangements"  with  hospitals for treatment and billing of
Government Program patients. Only hospitals can bill the Government Programs for
lithotripsy and thermotherapy services; thus contracting under arrangements with
hospitals was the way the Company Physician Entities  economically  participated
in the treatment of Government Program patients. Absent a restructuring of

                                        6

<PAGE>

traditional  operations to comply with the government's  interpretation of Stark
II, the physician-investors will be prohibited from referring Government Program
patients to the hospitals  contracting with the Company Physician Entities.  The
Company  cannot  predict when final Stark II  regulations  will be issued or the
substance  of the final  regulations,  but the  interpretive  provisions  of the
Proposed Stark  Regulations  may be viewed as the federal  government's  interim
enforcement   position  until  final   regulations  are  issued.   Restructuring
traditional  operations may reduce  Company  revenues and limit future growth by
(i) reducing or eliminating revenues attributable to the treatment of Government
Program patients by the Company Physician Entities,  (ii) reducing revenues from
the treatment of non-government  patients by Company  Physician  Entities due to
physician,  hospital and third-party  payor anxiety and concern created by Stark
II,  (iii)  requiring  the  Company  Physician  Entities  to  restructure  their
operations  to comply  with  Stark  II,  (iv)  restricting  the  acquisition  or
development of additional lithotripsy or thermotherapy operations that will both
treat Government  Program patients and have referring  physician-investors,  (v)
impairing  the  Company's   relationship  with  urologists  and  (vi)  otherwise
materially adversely impacting the Company.

         Many states  currently  have laws  similar to Stark II that  restrict a
physician with a financial  relationship with an entity from referring  patients
to that entity.  Often these laws contain statutory exceptions for circumstances
where the referring  physician,  or a member of his practice group, treats their
own patients.  States also commonly  require  physicians to disclose to patients
their financial  relationship with an entity. The Company believes that it is in
material   compliance   with  these  state  laws.   Nevertheless,   these  state
self-referral laws, as applied to activities and relationships  similar to those
of  the  Company,  have  been  subjected  to  limited  judicial  and  regulatory
interpretation,  and the Company has not  obtained or applied for any opinion of
any  regulatory  or  judicial   authority  that  its  business   operations  and
affiliations are in compliance with these laws. Therefore,  no assurances can be
given that the Company's activities will be found to be in compliance with these
laws if scrutinized by such authorities.

         In  addition,  upon  the  occurrence  of  changes  in the law  that may
adversely affect  operations,  the Company is required to purchase the interests
of  physician-investors  for certain of the Company  Physician  Entities.  These
mandatory purchase  obligations require the payment by the Company of a multiple
of earnings  similar to  multiples  used by the Company in pricing the  original
acquisition of such interests. To the extent the Company is required to purchase
such  interests,  such  purchases  might cause a default  under the terms of the
Company's  senior  credit  facility and senior  subordinated  notes,  impair the
Company's  relationship  with  physicians and otherwise have a material  adverse
impact on the  Company.  Regulatory  developments,  such as Stark II, might also
dictate that the Company purchase all the interests of its  physician-investors,
regardless of any contractual  requirements to do so, or substantially alter its
business  and  operations  to  remain  in  compliance  with   applicable   laws.
Accordingly,  there can be no assurance that the Company will not be required to
change its business practices or its investment relationships with physicians or
that the Company will not  experience a material  adverse  effect as a result of
any challenge made by a federal or state regulatory  agency. In addition,  there
can be no assurance  that  physician-investors  who,  voluntarily  or otherwise,
divest of their interests in Company  Physician  Entities will continue to refer
patients at the same rate or at all.

         Some states require  approval,  usually in the form of a certificate of
need  ("CON"),  prior to the  purchase of major  medical  equipment  exceeding a
predesignated  capital expenditure  threshold or for the commencement of certain
clinical health services.  Such approval is generally based upon the anticipated
utilization  of the  service  and the  projected  need  for the  service  in the
relevant geographical area of the state where the service is to be provided. CON
laws  differ in many  respects,  and not every  state's  CON law  applies to the
Company.  Most of the  Company's  operations  originated in states which did not
require a CON for the Company's services,  and the Company has obtained a CON in
states  where  one  is  required.  Some  states  also  require  registration  of
lithotripters with the state agency which administers its CON program. Such

                                        7

<PAGE>

registration  is  not  subject  to  any  required  approval,  but  rather  is an
administrative  matter  imposed so that the state will be aware of all  existing
clinical health  services.  The Company  registers in those states which require
these filings.

         All states in which the Company  operates  require  registration of the
fluoroscopic  x-ray tubes which are utilized to locate the kidney stones treated
with the Company's lithotripters.  The registration  requirements are imposed in
order to facilitate periodic inspection of the fluoroscopic tubes.

         Some states have  regulations  that require  facilities  such as mobile
lithotripters  and   thermotherapy   facilities  to  be  licensed  and  to  have
appropriate  emergency  care  resources and  qualified  staff meeting the stated
educational  and experience  criteria.  The Company's  lithotripsy  equipment is
subject to  regulation  by the U.S.  Food & Drug  Administration,  and the motor
vehicles   utilized  to  transport  the   Company's   mobile   lithotripsy   and
thermotherapy  equipment are subject to safety regulation by the U.S. Department
of  Transportation  and the  states in which the  Company  conducts  its  mobile
lithotripsy  and  thermotherapy  business.  The Company  believes  that it is in
material compliance with these regulations.

         Except as  provided  herein,  the  Company  believes it complies in all
material  respects  with the  foregoing  laws  and  regulations,  and all  other
applicable  regulatory  requirements;  however,  these laws are complex and have
been broadly construed by courts and enforcement agencies. Thus, there can be no
assurance  that the Company will not be required to change its  practices or its
relationships  with  treating  physicians  who  are  investors  in  the  Company
Physician  Entities,  or that the Company will not experience  material  adverse
effects as a result of any investigations or enforcement actions by a federal or
state regulatory agency.

         A number of proposals  for  healthcare  reform have been made in recent
years,  some of which have included  radical  changes in the healthcare  system.
Healthcare  reform  could  result  in  material  changes  in the  financing  and
regulation of the healthcare business,  and the Company is unable to predict the
effect  of  such  changes  on  its  future  operations.  It  is  uncertain  what
legislation  on healthcare  reform,  if any, will  ultimately be  implemented or
whether other changes in the  administration  or  interpretation of governmental
healthcare programs will occur. There can be no assurance that future healthcare
legislation  or  other  changes  in  the  administration  or  interpretation  of
governmental  healthcare programs will not have a material adverse effect on the
results of operations of the Company.

Equipment

- ---------

         The Company  purchases  its  equipment,  and  maintenance  is generally
provided  pursuant to service  contracts with the  manufacturer or other service
companies.  The cost of a new lithotripter ranges from $400,000 to $600,000. For
mobile lithotripsy and thermotherapy, the Company either purchases or leases the
tractor,  usually for a term up to five years,  and  purchases  the trailer or a
self contained  coach.  The cost of the laser  equipment  utilized in RVC ranges
from $300,000 to $500,000.  The cost of new prostatherapy  equipment ranges from
$200,000 to $400,000.

Employees

- ---------

         As of March 15, 2000, the Company employed  approximately 301 full-time
employees and approximately 72 part-time employees.

                                        8

<PAGE>

Competition

- -----------

         The market to provide  lithotripsy  services is highly  fragmented  and
competitive.  The Company  competes  with other private  facilities  and medical
centers  that  offer  lithotripsy  services  and  with  hospitals,  clinics  and
individual medical  practitioners that offer conventional  medical treatment for
kidney stones.  Certain of the Company's current and potential  competitors have
substantially  greater financial resources than the Company and may compete with
the Company for  acquisitions  and development of operations in markets targeted
by the Company. A decrease in the purchase price of lithotripters as a result of
the  development  of less  expensive  lithotripsy  equipment  could decrease the
Company's  competitive  advantage.  Most of the Company's  lithotripsy  services
agreements  have matured past their initial terms and are now in annual  renewal
terms or are on a  month-to-month  basis.  The Company also  competes with three
public companies,  all of which are also manufacturers of lithotripsy equipment,
which may create different  incentives for such providers in pricing lithotripsy
services.  Moreover,  while the Company believes that lithotripsy has emerged as
the superior  treatment  for kidney stone  disease,  the Company  competes  with
alternative kidney stone disease treatments.

         The  Company's  manufacturing  segment  competes  with at  least  three
privately held,  national  companies.  The primary competitive factors are price
and quality, including product manufacturing differences.  Additionally,  two of
the three largest competitors are certified to provide GE trailers.  The Company
believes it manufactures a high quality product at a competitive price.

         The RVC market is fragmented and competitive. The Company competes with
several  national,  public  companies  as well as  individual  ophthalmologists,
hospitals and smaller service  companies.  The principal methods for competition
are pricing and quality issues.  The larger competitors are primarily focused on
pricing,  while the smaller  competitors  compete using both pricing and quality
issues. While there are lower cost competitors in the geographic areas where the
Company  currently  has  operations,  the Company  believes it provides a higher
quality service for a competitive price.

ITEM 2.  PROPERTIES
- -------  ----------

         The Company's principal executive office is located in Austin, Texas in
an office building owned by American Physicians Service Group, Inc. ("APS"). The
Company pays APS approximately  $10,000 per month, which includes rental payment
for  approximately  6,700 square feet of office  space,  reception and telephone
services,  and certain  other  services and  facilities.  The office space lease
expires in December 2002.

         The Company leases  approximately 11,000 square feet of office space in
Fayetteville,  North  Carolina  under two leases  expiring in 2001.  The current
monthly lease amount is approximately $10,000.

         The  Company's  manufacturing  subsidiary  owns a  building  containing
approximately  78,000 square feet of  manufacturing  and office space in Harvey,
Illinois.

ITEM 3.  LEGAL PROCEEDINGS
- -------  -----------------

         The Company is involved in various  claims and legal  actions that have
arisen  in the  ordinary  course  of  business.  Management  believes  that  any
liabilities  arising from these actions will not have a material  adverse effect
on the financial condition, results of operations or cash flows of the Company.

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS
- -------  ---------------------------------------------------

         NONE.

                                        9

<PAGE>

                                     PART II

ITEM 5. MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER MATTERS
- -----------------------------------------------------------------------------

         The following  table sets forth the high and low closing prices for the
Company's  common  stock  in the  over-the-counter  market  as  reported  by the
National  Association of Securities Dealers,  Inc., Automated Quotations System,
for the years ended December 31, 1999 and 1998 (NASDAQ Symbol "PMSI").

                                 1999                        1998
                           -------------------          ------------------
                             High         Low            High         Low

     First Quarter         $ 8.44       $ 7.13          $13.38       $9.88
     Second Quarter        $ 7.56       $ 6.75          $12.06       $8.62
     Third Quarter         $ 9.75       $ 7.44          $ 9.06       $7.00
     Fourth Quarter        $10.63       $ 8.13          $ 8.00       $6.88

         On March 15, 2000, the Company had  approximately 627 holders of record
of its common stock.

         The Company has not  declared  any cash  dividends  on its common stock
during the last two years and has no present  intention  of  declaring  any cash
dividends in the foreseeable  future. In addition,  the Company is not permitted
by its current credit facility and terms of senior subordinated notes to declare
or make any payments  for  dividends.  It is the present  policy of the Board of
Directors to retain all earnings to provide funds for the growth of the Company.
The declaration and payment of dividends in the future will be determined by the
Board of  Directors  based upon the  Company's  earnings,  financial  condition,
capital  requirements,  loan  covenants  and such other  factors as the Board of
Directors may deem relevant.

ITEM 6.  SELECTED FINANCIAL DATA
- -------  -----------------------

<TABLE>

<S>                           <C>            <C>            <C>            <C>            <C>

(In thousands, except
per share data)                                   Years Ended December 31
                                                  -----------------------

                                1999           1998           1997           1996           1995
                                ----           ----           ----           ----           ----

Revenues:

    Lithotripsy                $89,180        $92,053        $93,113        $71,602        $22,153

    Other                       22,994         12,583          2,866            802          1,042
                              --------       --------       --------       --------       --------

    Total                     $112,174       $104,636        $95,979        $72,404        $23,195
                              ========       ========       ========       ========       ========

Income:

    Net income                 $15,039        $10,794        $14,856         $8,961         $7,204
                               =======        =======        =======         ======         ======

Diluted earnings per share       $0.88          $0.57          $0.76          $0.49          $0.48
                                 =====          =====          =====          =====          =====

Dividends per share               None           None           None           None           None

Total assets                  $246,826       $240,198       $224,905       $201,175        $77,627
                              ========       ========       ========       ========        =======

Long-term obligations         $103,797       $100,987        $71,198        $70,910        $22,323
                              ========       ========        =======        =======        =======
</TABLE>

                                       10

<PAGE>

Quarterly Data                  March 31    June 30     Sept 30      Dec 31
                                --------    --------    --------    --------

1999

Revenues                         $25,382     $28,608     $30,632     $27,552
Net income                        $3,162      $4,302      $4,339      $3,236
Per share amounts (basic):
    Net income                     $0.18       $0.25       $0.26       $0.20
    Weighted average shares
       outstanding                17,387      17,098      16,818      16,553
Per share amounts (diluted):
    Net income                     $0.18       $0.25       $0.26       $0.19
    Weighted average shares
       outstanding                17,495      17,196      17,000      16,788

1998

Revenues                         $22,795     $25,029     $28,936     $27,876
Net income (loss)                $(1,168)     $3,517      $3,941      $4,505
Per share amounts (basic):
    Net income                    $(0.06)      $0.18       $0.21       $0.25
    Weighted average shares
       outstanding                19,313      19,088      18,437      17,781
Per share amounts (diluted):
    Net income                    ($0.06)       $0.18       $0.21       $0.25
    Weighted average shares
       outstanding                19,313      19,223      18,561      17,890


ITEM 7.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
- -------  ---------------------------------------------------------------
         RESULTS OF OPERATIONS OF THE COMPANY
         ------------------------------------

Forward-Looking Statements

- --------------------------

     The  statements  contained  in this Report on Form 10-K that are not purely
historical are  forward-looking  statements within the meaning of Section 27A of
the  Securities  Act of 1933 and Section 21E of the  Securities  Exchange Act of
1934,  including  statements  regarding  the  Company's   expectations,   hopes,
intentions or strategies  regarding the future.  Readers  should not place undue
reliance on forward-looking  statements. All forward-looking statements included
in this document are based on  information  available to the Company on the date
hereof, and the Company assumes no obligation to update any such forward-looking
statements.  It is important to note that the  Company's  actual  results  could
differ materially from those in such forward-looking  statements. In addition to
any risks and uncertainties specifically identified in the text surrounding such
forward-looking  statements,  the reader should consult the Company's reports on
Form 10-Q and other filings under the  Securities Act of 1933 and the Securities
Exchange  Act of 1934,  for factors  that could cause  actual  results to differ
materially from those presented.

                                       11

<PAGE>

     The  forward-looking  statements  included herein are necessarily  based on
various  assumptions  and estimates and are inherently  subject to various risks
and  uncertainties,  including risks and uncertainties  relating to the possible
invalidity of the underlying  assumptions and estimates and possible  changes or
developments  in  social,  economic,   business,  industry,  market,  legal  and
regulatory circumstances and conditions and actions taken or omitted to be taken
by  third  parties,  including  customers,   suppliers,  business  partners  and
competitors and  legislative,  judicial and other  governmental  authorities and
officials.  Assumptions related to the foregoing involve judgements with respect
to, among other things,  future economic,  competitive and market conditions and
future business  decisions,  all of which are difficult or impossible to predict
accurately and many of which are beyond the control of the Company.  Any of such
assumptions  could be inaccurate and  therefore,  there can be no assurance that
the  forward-looking  statements included in this Report on Form 10-K will prove
to be accurate.

Year ended December 31, 1999 compared to the year ended December 31, 1998
- -------------------------------------------------------------------------

         Total revenues increased $7,538,000 (7%) as compared to the same period
in 1998.  Revenues from  lithotripter  operations  decreased by $2,873,000  (3%)
primarily due to renegotiation of contracts which resulted in a larger number of
contracts providing for per diem pricing,  and contracts lost due to non-renewal
and competition. Despite the lithotripsy revenue declines, lithotripsy procedure
volume was constant from 1998 to 1999,  which the Company believes is indicative
of its market share preservation.  Manufacturing revenue increased by $6,461,000
(58%) due to increased sales of MRI trailers as well as the Company's  expansion
into  manufacturing and sales of cardiac  catheterization  lab trailers.  During
1998 the  manufacturing  facility became certified by GE to provide trailers for
MRI equipment.  RVC revenues were $3,414,000 in 1999 and included fee revenue of
$3,004,000  and  equity  income of  $410,000.  The  refractive  operations  were
acquired  during the third  quarter of 1999.  Prostatherapy  revenues  increased
$627,000  (52%) as1999  revenues  included a full year of  operations  for three
entities,  while 1998 revenues included a full year of operations for one entity
and a partial year of operations for two entities.

         Costs of services and general and  administrative  expenses  (excluding
depreciation  and  amortization)  increased  from  38% to 40%  of  revenues  and
increased  $5,466,000  (14%) in absolute  terms,  compared to the same period in
1998.  Cost  of  services  associated  with  lithotripter  operations  increased
$327,000 (1%) in absolute  terms and from 25% to 26% of  lithotripter  revenues.
Cost of services associated with manufacturing increased $3,676,000 (40%) due to
the  increase in sales.  Cost of services  associated  with RVC was  $1,954,000,
which  represents  approximately  4  months  of  operations.  Cost  of  services
associated with prostatherapy  increased  $482,000 due to increased  operations.
Corporate  expenses  decreased from 5% to 4% of revenues and increased  $101,000
(2%) in absolute  terms,  as the Company was able to  successfully  grow without
proportionately adding overhead.

         Other deductions  decreased $4,318,000 from 1998 to 1999. This decrease
is  attributable  to a  decrease  in loan  fees  and  stock  offering  costs  of
$4,412,000  due to costs  recognized in 1998 of $4,978,000  associated  with the
$100 million senior  subordinated notes offering and the $50 million increase in
the senior  revolving  credit  facility,  partially  offset by 1999  expenses of
$566,000  related  to a  restructuring  of the  Company's  $100  million  senior
revolving credit facility. Also contributing to the decrease in other deductions
was income recognition in 1999 of $1,140,000 due to the release of a contractual
obligation  related to a management  incentive  compensation  program accrued at
December 31,  1998.  These  decreases  were  partially  offset by an increase in
interest  expense of $939,000,  primarily  due to the $100 million debt offering
which closed in March 1998.

                                       12

<PAGE>

         Minority interest in consolidated  income decreased $282,000 in 1999 as
compared to 1998 primarily due to the decline in lithotripsy  revenue  discussed
above in certain of the Company's subsidiaries. Earnings before interest, taxes,
depreciation,  and amortization  (EBITDA) attributable to minority interests was
$28,554,000 for the year ended December 31, 1999 compared to $28,077,000 for the
same  period in 1998.  EBITDA is not  intended to  represent  net income or cash
flows from operating activities in accordance with generally accepted accounting
principles and should not be considered a measure of the Company's profitability
or liquidity.

         Income tax expense for 1999  increased  $2,055,000  over 1998 primarily
due to the increase in pretax income.

Year ended December 31, 1998 compared to the year ended December 31, 1997
- -------------------------------------------------------------------------

         Total revenues increased $8,657,000 (9%) as compared to the same period
in 1997.  Revenues from  lithotripter  operations  decreased by $1,060,000  (1%)
primarily due to a decline in average reimbursement per procedure. Manufacturing
revenue  increased by  $8,708,000  (369%) due to the fact that the 1998 revenues
were for the full year while 1997 revenues  were for four months of  operations.
The Company acquired the trailer  manufacturer in September 1997.  Prostatherapy
revenues  rose  $1,207,000  due to the fact that 1998 revenues were for the full
year for one entity and a partial year for another  entity,  while 1997 revenues
included one entity which began operations in the fourth quarter. Other revenues
decreased $198,000 primarily due to four discontinued/sold cardiac centers.

         Costs of services and general and  administrative  expenses  (excluding
depreciation  and  amortization)  increased  from  35% to 38%  of  revenues  and
increased  $6,188,000  (19%) in absolute  terms,  compared to the same period in
1997.  Cost  of  services  associated  with  lithotripter  operations  decreased
$2,707,000 (11%) in absolute terms and from 27% to 25% of lithotripter revenues.
Cost of services associated with manufacturing  increased  $7,461,000 (428%) due
to full year of  operations  in 1998 while 1997 costs  represent  four months of
operations.  Cost of services  associated with prostatherapy  increased $803,000
due to a full year of  operations  for the  first  time in 1998.  Other  cost of
services  decreased  $229,000  (48%)  primarily  due to  four  discontinued/sold
cardiac centers.  Corporate expenses decreased from 6% to 5% of revenues, as the
Company was able to successfully grow without  proportionately  adding overhead.
Corporate  expenses decreased $757,000 (13%) primarily due to a consolidation of
corporate functions.

         Other deductions increased $4,635,000 primarily due to (i) the increase
of $4,618,000 for the write-off of fees paid to lenders to obtain financing, and
(ii) an  increase  in  interest  expense of  $992,000  due to an increase in new
borrowings in March 1998 related to the $100 million senior  subordinated  notes
offering.  The  increased  deductions  were offset  partially  by an increase in
interest income of $677,000.

         Minority interest in consolidated  income decreased  $251,000 primarily
due to the  decline in  revenue  discussed  above in  certain  of the  Company's
subsidiaries.  EBITDA attributable to minority interests was $28,077,000 for the
year ended  December  31, 1998  compared to  $28,591,000  for the same period in
1997.

         Income tax expense for 1998 increased $1,582,000 over 1997, despite the
12%  reduction  in pretax  earnings  over the same period as the 1997  provision
included the effect of a reduction in the Company's  valuation allowance related
to net operating loss carryforwards.

Liquidity and Capital Resources

         Cash and cash  equivalents were $20,064,000 and $40,146,000 at December
31, 1999 and 1998, respectively. The Company's subsidiaries generally distribute
all of their available cash quarterly, after establishing reserves for estimated
capital  expenditures and working capital. For the years ended December 31, 1999
and  1998,  the  Company's   subsidiaries   distributed  cash  of  approximately
$27,180,000 and $25,799,000, respectively, to minority interest holders.

                                       13

<PAGE>

         Cash provided by operations was $35,744,000 for the year ended December
31, 1999 and $45,551,000 for the year ended December 31, 1998. From 1998 to 1999
fee and other revenue  collected  increased by $9,602,000  and was offset by the
increase  in  cash  paid  to  employees,   suppliers  of  goods  and  others  of
$12,396,000. These fluctuations are attributable to increased operations as well
as the timing of  accounts  receivable  collections  and  accounts  payable  and
accrued expense payments. An increase in interest payments of $2,092,000 was due
to the $100 million of senior subordinated notes issued in March 1998, resulting
in a partial  year of interest  payments on this debt in 1998 versus a full year
of interest  payments on this debt in 1999.  Taxes paid increased  $790,000 from
1998 to 1999 due to higher  income tax expense  during 1999.  Additionally,  the
Company purchased  investments in a trading portfolio of $9,222,000 during 1999,
partially offset by proceeds from sales and maturities of $5,003,000.

         Cash used by investing activities for the year ended December 31, 1999,
was $26,241,000 primarily due to $23,580,000 used in two refractive acquisitions
and one  lithotripter  acquisition  as well as payments  of earnouts  related to
prior year  acquisitions.  Purchases of equipment and leasehold  improvements of
$5,790,000   were  partially   offset  by  $2,352,000  in   distributions   from
investments.  Cash used by investing  activities for the year ended December 31,
1998, was  $2,142,000  primarily due to $5,213,000 for the purchase of equipment
and leasehold improvements, partially offset by $2,532,000 in distributions from
investments.

         Cash used in financing activities for the year ended December 31, 1999,
was $29,585,000,  which was primarily due to distributions to minority interests
of $27,180,000 and purchases of treasury stock of $8,382,000 partially offset by
net  borrowings  of $3,181,000  and  contributions  of $2,636,000  received from
holders of minority interests related to expansion of existing  partnerships and
new partnership formations. Cash used in financing activities for the year ended
December 31, 1998, was  $27,033,000,  primarily due to distributions to minority
interests of  $25,799,000,  purchases of treasury stock of $16,439,000  and debt
issuance costs of $4,417,000, partially offset by net borrowings of $19,541,000.

         The Company's credit facility as of December 31, 1999 is comprised of a
revolving line of credit.  The revolving line of credit has a borrowing limit of
$100  million,  none of which was drawn at December 31, 1999 and March 15, 2000.
Subsequent  to December 31, 1999 the Company  completed a  restructuring  of its
revolving  line of credit to enable the Company to draw on the  revolver for RVC
acquisitions.  The  restructuring  splits the revolver  into two  facilities  of
$14,000,000  for  refractive   acquisitions  by  certain  subsidiaries  and  the
remaining   $86,000,000   for   lithotripsy,   manufacturing,   refractive   and
prostatherapy  acquisitions as well as for working  capital.  On March 27, 1998,
the Company completed an offering of $100 million of senior  subordinated  notes
due 2008 (the "Notes") to qualified  institutional buyers. The net proceeds from
the  offering of  approximately  $96  million was used to repay all  outstanding
indebtedness  under the Company's  bank  facility,  with the remainder  used for
general corporate purposes, including acquisitions. In connection therewith, the
Company recorded a charge to earnings in 1998 of approximately  $4.4 million for
debt issuance costs  associated with the Notes. The Notes bear interest at 8.75%
and interest is payable semi-annually on April 1st and October 1st. Principal is
due April 2008.

         The  Company   intends  to  increase  the  number  of  its  lithotripsy
operations  primarily through  acquisitions and the number of its RVC operations
through  both  acquisitions  and  development.  The Company  intends to fund the
purchase price for future  acquisitions and developments  using borrowings under
its senior  credit  facility and cash flow from  operations.  In  addition,  the
Company  may  use  shares  of  its  common  stock  in  such  acquisitions  where
appropriate.

                                       14

<PAGE>

         During 1998, the Company announced a stock repurchase  program of up to
$25.0  million of common  stock.  In  February  2000 the  Company  announced  an
increase  in the  authorized  repurchase  amount  from  $25.0  million  to $35.0
million.  From time to time, the Company may purchase  additional  shares of its
common stock where,  in the judgment of  management,  market  valuations  of its
stock do not  accurately  reflect the Company's  past and  projected  results of
operations. The Company intends to fund any such purchases using available cash,
cash flow from operations and borrowings under its senior credit  facility.  The
Company has purchased 2,968,800 shares of stock for a total of $25,572,000 as of
March 15, 2000.

         The Company's ability to make scheduled payments of principal of, or to
pay the  interest  on, or to  refinance,  its  indebtedness,  or to fund planned
capital expenditures will depend on its future performance,  which, to a certain
extent, is subject to general  economic,  financial,  competitive,  legislative,
regulatory and other factors that are beyond its control. Based upon the current
level of operations and anticipated cost savings and revenue growth,  management
believes  that cash flow from  operations  and  available  cash,  together  with
available borrowings under its senior credit facility,  will be adequate to meet
the  Company's  future  liquidity  needs  for at least the next  several  years.
However,  there can be no assurance  that the  Company's  business will generate
sufficient  cash flow from  operations,  that  anticipated  revenue  growth  and
operating  improvements  will be  realized  or that  future  borrowings  will be
available under the senior credit facility in an amount sufficient to enable the
Company to service its indebtedness or to fund its other liquidity needs.

Inflation

- ---------

         The  operations  of the  Company  are  not  significantly  affected  by
inflation because the Company is not required to make large investments in fixed
assets.  However,  the rate of inflation  will affect  certain of the  Company's
expenses, such as employee compensation and benefits.

ITEM 7.A  QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
- --------  ----------------------------------------------------------

Interest Rate Risk:
         The Company has long-term debt  (including  current  portion)  totaling
$105,560,000,  of which  $100.8  million  has a fixed rate of interest of 8.75%,
$126,000  has fixed rates of 6% to 9% and $162,000  does not bear any  interest.
The  remaining  $4,464,000  bears  interest  at the prime  rate.  The Company is
exposed to some market risk due to the floating interest rate on the $4,464,000.
The Company makes monthly or quarterly payments of principal and interest on the
$4,464,000.  An  increase in  interest  rates of 1.5% would  result in a $67,000
annual increase in interest expense on this existing principal balance.

ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA
- -------  -------------------------------------------

     The  information  required by this item is contained in Appendix A attached
hereto.

ITEM 9.  CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
- -------  ---------------------------------------------------------------
         FINANCIAL DISCLOSURE
         --------------------
     None.



                                       15

<PAGE>

                                    PART III

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT
- -----------------------------------------------------------

     The information  required by this item is contained in the definitive proxy
material of the Company to be filed in connection  with its 2000 annual  meeting
of shareholders,  except for the information regarding executive officers of the
Company,  which is  presented  below.  The  information  required  by this  item
contained in such definitive proxy material is incorporated herein by reference.

As of March 15, 2000, the executive officers of the Company are as follows:

Name                          Age   Position

- ----                          ---   --------

Kenneth S. Shifrin            50    Chairman of the Board
Joseph Jenkins, M.D., J.D.    52    President, Chief Executive Officer and
                                       Director

Brad A. Hummel                43    Executive Vice President and Chief
                                       Operating Officer
Cheryl L. Williams            48    Chief  Financial  Officer, Senior Vice
                                       President-Finance and Secretary
Teena E. Belcik               37    Vice President and Treasurer
John R. Hedrick               47    Senior Vice President of Development
Stan Johnson                  46    Vice President

The foregoing  does not include  positions  held in the Company's  subsidiaries.
Officers  are  elected  for annual  periods.  There are no family  relationships
between any of the executive officers and/or directors of the Company.

Mr.  Shifrin has been  Chairman of the Board and a director of the Company since
October 1989. In addition, Mr. Shifrin has served in various capacities with APS
since February 1985, and is currently  Chairman of the Board and Chief Executive
Officer of APS. Mr. Shifrin is a member of the World Presidents' Organization.

Dr. Jenkins has been President and Chief Executive Officer and a director of the
Company since April 1996.  From May 1990 until  December 1991, Dr. Jenkins was a
Vice President of  Lithotripters,  Inc. Since January 1992, Dr. Jenkins has been
President of Lithotripters,  Inc. Dr. Jenkins is a board certified urologist and
is a founding  member, a past president and currently a director of the American
Lithotripsy  Society.

Mr. Hummel has been the Executive Vice President and Chief Operating  Officer of
the Company  since October  1999.  Prior to joining the Company,  Mr. Hummel was
with Diagnostic Health Services,  Inc. ("DHS") since 1984, most recently serving
as the President and Chief  Executive  Officer,  and as a member of the Board of
Directors.  The Company believes that DHS filed for Chapter 11 reorganization on
or about March 20, 2000.  From 1981 to 1984,  Mr.  Hummel was an associate  with
Covert,  Crispin and Murray,  a  Washington,  D.C. and  London-based  management
consulting firm. Mr. Hummel also serves as a member of APS's Board of Directors.

Ms. Williams has been Chief Financial  Officer,  Senior Vice President - Finance
and Secretary of the Company since October 1989. Ms.  Williams was Controller of
Fairchild  Aircraft  Corporation  from August 1988 to October 1989. From 1985 to
1988, Ms. Williams served as the Chief Financial Officer of APS Systems, Inc., a
wholly-owned subsidiary of APS.



                                       16

<PAGE>

Ms. Belcik has been Vice President and Treasurer  since October 1999. Ms. Belcik
served  various  positions  with Bank of America,  N.A.  since 1994 and was most
recently a Senior Vice President in the Health Care Banking  Group.  Previously,
Ms. Belcik taught at Valdosta State University,  was a financial consultant, and
held several positions with Chase Bank's Corporate Banking Group.

Mr. Hedrick has been the Senior Vice President of  Development  since  September
1999.  Mr. Hedrick was with a subsidiary of American  Physicians  Service Group,
Inc. ("APS") since 1997 serving as Senior Vice President.  From 1988 to 1997 Mr.
Hedrick's experience included providing merger and acquisition advisory services
to privately held healthcare entities, including ophthalmology, and the practice
of law.

Mr.  Johnson  has been a Vice  President  of the Company  and  President  of Sun
Medical Technologies,  Inc. ( "Sun "), a wholly-owned subsidiary of the Company,
since November 1995.  Mr.  Johnson was the Chief  Financial  Officer of Sun from
1990 to 1995.

ITEM 11. EXECUTIVE COMPENSATION
- -------------------------------

         The  information  required by this item is contained in the  definitive
proxy  statement of the Company to be filed in  connection  with its 2000 annual
meeting of shareholders, which information is incorporated herein by reference.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT
- -------  --------------------------------------------------------------

         The  information  required by this item is contained in the  definitive
proxy  statement of the Company to be filed in  connection  with its 2000 annual
meeting of shareholders, which information is incorporated herein by reference.

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS
- -------------------------------------------------------

         The  information  required by this item is contained in the  definitive
proxy  statement of the Company to be filed in  connection  with its 2000 annual
meeting of shareholders, which information is incorporated herein by reference.

                                     PART IV

ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K
- -------  ----------------------------------------------------------------

(a)  1.  Financial Statements.
         --------------------

         The  information  required  by this item is  contained  in  Appendix  A
attached hereto.

     2.  Financial Statement Schedules.
         -----------------------------

         None.

(b)  Reports on Form 8-K.
     -------------------

         None.



                                       17

<PAGE>
(c)  Exhibits. (1)
     --------

     3.1    Certificate of Incorporation of the Company. (2)

     3.2    Bylaws of the Company. (2)

     4.1    Specimen of Common Stock Certificate. (2)

     10.1*  Prime Medical Services, Inc. 1993 Stock Option Plan. (3)

     10.2*  First Amendment to the Prime Medical Services, Inc. 1993 Stock
            Option Plan. (12)

     10.3*  Second Amendment to the Prime Medical Services, Inc. 1993 Stock
            Option Plan. (12)

     10.4*  Third Amendment to the Prime Medical Services, Inc. 1993 Stock
            Option Plan. (13)

     10.5   Rights Agreement dated October 18, 1993 between the Company and
            American Stock Transfer and Trust Company. (3)

     10.6   Form of  Indemnification  Agreement  dated  October 11, 1993
            between the Company and certain of its officers and directors. (3)

     10.7   Partnership Agreement of Metro Atlanta Stonebusters, G.P. (5)

     10.8   Management Agreement dated July 28, 1994 between the Alabama Renal
            Stone Institute, Inc. and Alabama Kidney Stone Foundation, Inc. (6)

     10.9   Asset Purchase Agreement dated July 21, 1999 among Prime Lithotripsy
            Services, Inc., Reston Hospital Lithotripter Joint Venture, Reston
            Lithotripsy Associates, Inc., Columbia Arlington Healthcare System,
            L.L.C. and Robert Ball, M.D. (15)

     10.10  Not used

     10.11  Not used

     10.12  Not used

     10.13  Not used

     10.14  Amended and Restated Joint Venture Agreement dated April 1989,
            between Prime Diagnostic Imaging Services, Inc. and The Shasta
            Diagnostic Imaging Medical Group. (4)

     10.15  Agreement of Limited Partnership of Mobile Kidney Stone Centers of
            California III, L.P. (15)

     10.16  Amendments to First Amended and Restated Agreement of Limited
            Partnership of Ohio Mobile Lithotripter, Ltd. (15)

     10.17  Second Amendment to Agreement of Limited Partnership of Pacific
            Medical Limited Partnership (15)



                                       18

<PAGE>

     10.18  Amendments to Agreement of Limited Partnership of Texas Lithotripsy
            Limited Partnership VII, L.P. (15)

     10.19  Fourth Amendment to Agreement of Limited Partnership of San Diego
            Lithotripters Limited Partnership (15)

     10.20  Amendment to Agreement of Limited Partnership of Fayetteville
            Lithotripters Limited Partnership - Virginia I (15)

     10.21  Amendments to Agreement of Limited Partnership of Fayetteville
            Lithotripters Limited Partnership - South Carolina II (15)

     10.22  Amendment to Agreement of Limited Partnership of Fayetteville
            Lithotripters Limited Partnership - Utah I (15)

     10.23  Third Amendment to Agreement of Limited Partnership of Florida
            Lithotripters Limited Partnership I (15)

     10.24  Fourth Amendment to Agreement of Limited Partnership of Indiana
            Lithotripters Limited Partnership I (15)

     10.25  Sixth Amendment to Agreement of Limited Partnership of Texas
            Lithotripsy Limited Partnership III, L.P. (15)

     10.26  Agreement of Limited Partnership of Mobile Kidney Stone Centers of
            California II, L.P. (15)

     10.27  Fourth Amendment to Agreement of Limited Partnership of Louisiana
            Lithotripsy Investment Limited Partnership (15)

     10.28  Operating Agreement for Southern California Stone Center, L.L.C. (9)

     10.29  Lease Agreement  dated July 1, 1995 between Kidney Stone Center of
            South Florida, L.C. and Madorsky and Pinon Kidney Stone Center of
            South Florida, P.A. (9)

     10.30  Agreement of Limited Partnership of Texas I Prostatherapy Limited
            Partnership (15)

     10.31  Not used

     10.32  Partnership Interest Purchase Agreement dated May 1, 1997 among
            Prime Lithotripter Operations, Inc., Tenn-Ga Stone Group Two, L.P.,
            NGST, Inc. and all the Shareholders of NGST, Inc. (12)

     10.33  Stock Purchase Agreement dated June 1, 1997 between Sun Medical
            Technologies, Inc. and Executive Medical Enterprises, Inc. (12)

     10.34  Contribution Agreement dated October 8, 1997 between Prime Medical
            Services, Inc. and AK Associates. (12)

     10.35  Confidential Assignment Summary for Pacific Medical Limited
            Partnership. (14)

     10.36  Limited Partnership Agreement for Texas Lithotripsy VII, L.P. (14)



                                       19

<PAGE>

     10.37  Agreement and Plan of Merger of Texas Lithotripsy Limited
            Partnership II, L.P., Texas Lithotripsy Limited Partnership IV, L.P.
            and Texas ESWL/Laser Lithotripter, Ltd. (14)

     10.38  Limited Partnership Agreement for Big Sky Urological Limited
            Partnership. (14)

     10.39  Operating Agreement for Kentucky I Lithotripsy, LLC. (14)

     10.40  Confidential Private Placement Memorandum for Tennessee Valley
            Lithotripter Limited Partnership. (14)

     10.41  Confidential Private Placement Memorandum for Fayetteville
            Lithotripters Limited Partnership - Arkansas I. (14)

     10.42  Confidential Private Placement Memorandum for Texas Lithotripsy
            Limited Partnership I, L.P. (14)

     10.43  Operating Agreement for Washington Urological Services, LLC. (14)

     10.44* Amended and Restated 1993 Stock Option Plan, as amended June 10,
            1998. (10)

     10.45  Agreement of Limited Partnership of Wyoming Urological Services,
            L.P. (14)

     10.46  Indenture Agreement dated March 27, 1998 between Prime Medical
            Services, Inc. and State Street Bank and Trust Company of Missouri,
            N.A. (8)

     10.47  Loan Agreement dated January 31, 2000 for $14,000,000 Advancing Term
            Loan between Prime Refractive Management, L.L.C., Bank of America,
            N.A. as Administrative Agent, Bank Boston, N.A. as Documentation
            Agent and the Lenders Named Therein (15)

     10.48  Fourth Amended and Restated Loan Agreement dated January 31, 2000
            for $86,000,000 Revolving Credit Loan between Prime Medical Services
            Inc., Bank of America, N.A. as Administrative Agent, BankBoston,
            N.A. as Documentation Agent and the Lenders Named Therein (15)

     10.49  Pledge and Security  Agreements  dated  January 31, 2000 relating to
            $14,000,000  Advancing Term Loan and  $86,000,000  Revolving  Credit
            Loan (15)

     10.50  Borrower  Security  Agreements  dated  January 31, 2000  relating to
            $14,000,000  Advancing Term Loan and  $86,000,000  Revolving  Credit
            Loan (15)

     10.51  Guarantor  Security  Agreements  dated  January 31, 2000 relating to
            $14,000,000  Advancing Term Loan and  $86,000,000  Revolving  Credit
            Loan (15)

     10.52  Guarantor Copyright Security Agreements dated January 31, 2000
            relating to $14,000,000 Advancing Term Loan and $86,000,000
            Revolving Credit Loan (15)

     10.53  Guaranty  Agreements  dated January 31, 2000 relating to $14,000,000
            Advancing Term Loan and $86,000,000 Revolving Credit Loan (15)

     10.54  Note dated January 31, 2000 in the amount of $1,050,000 between
            Prime Refractive Management and Guaranty Federal Bank, F.S.B. (15)



                                       20

<PAGE>

     10.55  Note dated  January  31,  2000 in the amount of  $1,575,000  between
            Prime Refractive Management and Fleet National Bank (15)

     10.56  Note dated January 31, 2000 in the amount of $3,150,000 between
            Prime Refractive Management and BankBoston, N.A. (15)

     10.57  Note dated January 31, 2000 in the amount of $4,725,000 between
            Prime Refractive Management and Bank of America, N.A. (15)

     10.58  Note dated January 31, 2000 in the amount of $2,100,000 between
            Prime Refractive Management and Bank One, Texas, N.A. (15)

     10.59  Note dated January 31, 2000 in the amount of $12,900,000 between
            Prime Medical Services, Inc. and Bank One, Texas, N.A. (15)

     10.60  Note dated January 31, 2000 in the amount of $8,600,000 between
            Prime Medical Services, Inc. and LaSalle Bank, National
            Association (15)

     10.61  Note dated January 31, 2000 in the amount of $8,600,000 between
            Prime Medical Services, Inc. and Cooperative Centrale
            Raiffeisen-Boerenleenbank B.A., "Rabobank Nederland", New York
            Branch (15)

     10.62  Note dated January 31, 2000 in the amount of $8,600,000 between
            Prime Medical Services, Inc. and Credit Lyonnais New York
            Branch (15)

     10.63  Note dated January 31, 2000 in the amount of $5,375,000 between
            Prime Medical Services, Inc. and Fleet National Bank (15)

     10.64  Note dated January 31, 2000 in the amount of $8,600,000 between
            Prime Medical Services, Inc. and Imperial Bank(15)

     10.65  Note dated January 31, 2000 in the amount of $6,450,000 between
            Prime Medical Services, Inc. and Guaranty Federal Bank, F.S.B. (15)

     10.66  Note dated January 31, 2000 in the amount of $16,125,000 between
            Prime Medical Services, Inc. and Bank of America, N.A. (15)

     10.67  Note dated January 31, 2000 in the amount of $10,750,000 between
            Prime Medical Services, Inc. and BankBoston,  N.A. (15)

     10.68  Note dated  January  31,  2000 in the amount of  $1,400,000  between
            Prime Refractive Management and LaSalle Bank, National
            Association (15)

     10.69  Not used

     10.70  Contribution Agreement dated September 1, 1999 and First Amendment
            dated January 31, 2000 among Barnet Dulaney Eye Center,  P.L.L.C.,
            David Dulaney,  M.D., Ronald W. Barnet, M.D., Mark Rosenberg,
            Prime Medical Services Inc., Prime Medical Operating Inc., LASIK
            Investors, L.L.C., Prime/BDR Acquisition, L.L.C. and Prime/BDEC
            Acquisition,  L.L.C. (15)



                                       21

<PAGE>

     10.71  Loan Agreement dated September 1, 1999 between Prime Medical
            Operating, Inc. and Prime/BDR Acquisition, L.L.C. (15)

     10.72  Limited Liability Company Agreement of Prime/BDR Acquisition,
            L.L.C. (15)

     10.73  Limited Liability Company Agreement of Prime/BDEC Acquisition,
            L.L.C. (15)

     10.74  Non-Competition Agreements dated September 1, 1999 between Robert
            B. Pinkert, O.D. and Scott A. Perkins, M.D. for the benefit of Prime
            Medical Services Inc., Prime Medical Operating, Inc., Prime/BDR
            Acquisition, L.L.C., Prime/BDEC Acquisition,  L.L.C., Barnet Dulaney
            Eye Center, P.L.L.C., LASIK Investors, L.L.C., Ronald W. Barnet,
            M.D., David D. Dulaney, M.D., and Mark Rosenberg (15)

     10.75  Promissory Note dated September 1, 1999 from Prime/BDR Acquisition,
            L.L.C., to Prime Medical Operating, Inc. (15)

     10.76  Collocation Agreement dated September 1, 1999 by and between Barnet
            Dulaney Eye Center, P.L.L.C. and Prime/BDR Acquisition, L.L.C. (15)

     10.77  Membership Interest Transfer Restriction Agreement dated
            September 1, 1999 (15)

     10.78  Assignment and Security Agreement dated September 1, 1999 between
            Prime Medical Operating, Inc. and LASIK Investors, L.L.C. (15)

     10.79  Promissory Note dated September 1, 1999 from Prime/BDR Acquisition,
            L.L.C., to Prime Medical Operating, Inc. (15)

     10.80  Loan Agreement dated January 31, 2000 between Prime Refractive,
            L.L.C. and Prime Refractive Management, L.L.C. (15)

     10.81  Promissory Note dated January 31, 2000 between Prime Refractive,
            L.L.C. and Prime Refractive Management, L.L.C. (15)

     10.82  Assignment and Security Agreement dated January 31, 2000 between
            Prime Refractive Management, L.L.C. and LASIK Investors, L.L.C. (15)

     10.83  Limited Liability Company Agreement dated September 1, 1999 of Prime
            Refractive, L.L.C. (15)

     10.84  Stock Purchase Agreements dated September 1, 1999 relating to the
            acquisition of Horizon Vison Center, Inc. (15)

     10.85  Assignment and Security Agreements relating to the acquisition of
            Horizon Vison Center, Inc. (15)

     10.86  Exclusive Use Agreements relating to the acquisition of Horizon
            Vison Center, Inc. (15)

     10.87  Amended and Restated Bylaws for the regulation of Horizon Vison
            Centers, Inc. (15)

     10.88  Assignment and Security Agreement by and between Prime Medical
            Operating, Inc. and Prime/BDR Acquisition, L.L.C. (15)

     12     Computation of ratio of earnings to fixed charges.  (15)

     21.1   List of subsidiaries of the Company.  (15)

     23.1   Independent Auditors' Consent of KPMG LLP.   (15)

     27     Financial Data Schedule (15)

 --------------


     * Executive compensation plans and arrangements.


                                       22

<PAGE>
(1)  The exhibits  listed  above will be  furnished to any security  holder upon
     written  request  for such  exhibit to Cheryl L.  Williams,  Prime  Medical
     Services,  Inc., 1301 Capital of Texas Highway,  Suite C-300, Austin, Texas
     78746.  The  Securities  and Exchange  Commission  (the "SEC")  maintains a
     website that contains reports,  proxy and information  statements and other
     information  regarding registrants that file electronically with the SEC at
     "http://www.sec.gov".

(2)  Filed as an Exhibit to the Registration Statement on Form S-4 (Registration
     No. 33-56900) of the Company and incorporated herein by reference.

(3)  Filed as an Exhibit to the Current  Report on Form 8-K of the Company dated
     October 18, 1993 and incorporated herein by reference.

(4)  Filed  as an  Exhibit  to the  Annual  Report  on Form  10-K of Old  Prime,
     Commission  File Number 0- 9963,  for the year ended  December 31, 1992 and
     incorporated herein by reference.

(5)  Filed as an Exhibit to the Current  Report on Form 8-K dated May 5, 1994 of
     the Company and incorporated herein by reference.

(6)  Filed as an Exhibit to the  Current  Report on Form 8-K dated July 28, 1994
     of the Company and incorporated herein by reference.

(7)  Not used.

(8)  Filed as an  Exhibit  to the  Quarterly  Report on Form 10-Q for the period
     ended June 30,  1998

(9)  Filed as an Exhibit to the Annual  Report on Form 10-K of the  Company  for
     the year ended December 31, 1995.

(10) Filed as an Exhibit to the Registration Statement on Form S-8 (Registration
     No. 333-62245) of the Company and incorporated herein by reference.

(11) Not used.

(12) Filed as an Exhibit to the Annual  Report on Form 10-K of the  Company  for
     the year ended December 31, 1997.

(13) Filed as an  Exhibit  to the  Quarterly  Report on Form 10-Q for the period
     ended September 30, 1998.

(14) Filed as an Exhibit to the Annual  Report on Form 10-K of the  Company  for
     the year ended December 31, 1998.

(15) Filed herewith.



                                  23

<PAGE>

                                   SIGNATURES

     Pursuant  to the  requirements  of  Section  13 or 15(d) of the  Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.

                                   PRIME MEDICAL SERVICES, INC.







                                   By: /s/ Joseph Jenkins, M.D., J.D.
                                   -------------------------------
                                   Joseph Jenkins, M.D., J.D., President,
                                   Chief Executive Officer and Director


                                   Date:  March 30, 2000



     Pursuant to the  requirements of the Securities  Exchange Act of 1934, this
report has been signed by the following  persons on behalf of the registrant and
in the capacities and on the dates indicated.

By: /s/ Kenneth S. Shifrin

    ----------------------
    Kenneth S. Shifrin
    Chairman of the Board

Date:  March 30, 2000





By: /s/ Cheryl L. Williams

    ----------------------
    Cheryl L. Williams

    Senior Vice President of Finance, Secretary
    and Chief Financial Officer (Principal
    Financial and Accounting Officer)

Date:  March 30, 2000



                                  24

<PAGE>

By: /s/ Joseph Jenkins

    ----------------------
    Joseph Jenkins, M.D., President,
    Chief Executive Officer and Director

Date:  March 30, 2000





By: /s/ John McEntire

    ----------------------
     John McEntire, Director

Date:   March 30, 2000





By: /s/ William A. Searles

    ----------------------
    William A. Searles, Director

Date:  March 30, 2000





By: /s/ Michael Spalding

    ----------------------
    Michael Spalding, M.D., Director

Date:  March 30, 2000




By: /s/ James M. Usdan

    ----------------------
    James M. Usdan, Director

Date:  March 30, 2000



                                  25

<PAGE>

                                   APPENDIX A

                                      INDEX

                                                                         Page

Independent Auditors' Report                                             A-2
Consolidated Financial Statements:
     Consolidated Statements of Income for the years ended
        December 31, 1999, 1998 and 1997.                                A-3
     Consolidated Balance Sheets at December 31, 1999 and 1998.          A-4
     Consolidated Statements of Stockholders' Equity for the
        years ended December 31, 1999, 1998 and 1997.                    A-6
     Consolidated Statements of Cash Flows for the years ended
        December 31, 1999, 1998 and 1997.                                A-7
     Notes to Consolidated Financial Statements.                         A-10




                                       A-1

<PAGE>

                          Independent Auditors' Report

The Board of Directors and Shareholders
Prime Medical Services, Inc.:

We have audited the  accompanying  consolidated  financial  statements  of Prime
Medical   Services,   Inc.  and  subsidiaries   ("Company")  as  listed  in  the
accompanying   index.   These   consolidated   financial   statements   are  the
responsibility of the Company's management.  Our responsibility is to express an
opinion on these consolidated financial statements based on our audits.

We  conducted  our  audits  in  accordance  with  generally   accepted  auditing
standards.  Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements.  An audit also includes
assessing the  accounting  principles  used and  significant  estimates  made by
management,  as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the consolidated  financial statements referred to above present
fairly,  in all  material  respects,  the  financial  position of Prime  Medical
Services,  Inc. and  subsidiaries at December 31, 1999 and 1998, and the results
of their operations and their cash flows for each of the years in the three-year
period ended December 31, 1999, in conformity with generally accepted accounting
principles.

/s/:KPMG LLP

Austin, Texas
March 6, 2000

                                       A-2

<PAGE>

            PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                  CONSOLIDATED STATEMENTS OF INCOME

($ in thousands, except per share data)
<TABLE>

<S>                                                             <C>            <C>            <C>
                                                                     Years Ended December 31,
                                                                  1999           1998           1997
Revenue:
     Lithotripsy:
         Fee revenues                                            $ 80,880       $ 83,879       $ 84,537
         Management fees                                            5,719          5,284          6,237
         Equity income                                              2,581          2,890          2,339
                                                                 --------       --------       --------
                                                                   89,180         92,053         93,113
     Manufacturing                                                 17,527         11,066          2,358
     Refractive                                                     3,414              -              -
     Prostatherapy                                                  1,834          1,207              -
     Other                                                            219            310            508
                                                                 --------       --------       --------
         Total revenue                                            112,174        104,636         95,979
                                                                 --------       --------       --------
Cost of services and general and administrative expenses:

     Lithotripsy                                                   23,001         22,674         25,381
     Manufacturing                                                 12,880          9,204          1,743
     Refractive                                                     1,954              -              -
     Prostatherapy                                                  1,285            803              -
     Other                                                            165            249            478
     Corporate                                                      5,027          4,926          5,683
     Nonrecurring development, impairment
          and other costs, net                                        627          1,617              -
                                                                 --------       --------       --------
                                                                   44,939         39,473         33,285
Depreciation and amortization                                      10,848         10,476          9,911
                                                                 --------       --------       --------
         Total operating expenses                                  55,787         49,949         43,196
                                                                 --------       --------       --------

Operating income                                                   56,387         54,687         52,783

Other income (deductions):
     Interest and dividends                                         1,505          1,417            740
     Interest expense                                              (9,408)        (8,469)        (7,477)
     Loan fees and stock offering costs                              (566)        (4,978)          (360)
     Release of contractual obligation                              1,140              -              -
     Other, net                                                       (79)           304              6
                                                                 --------       --------       --------
                                                                   (7,408)       (11,726)        (7,091)
                                                                 --------       --------       --------
Income before provision for income taxes
     and minority interest                                         48,979         42,961         45,692

Minority interest in consolidated income                           24,508         24,790         25,041

Provision for income taxes                                          9,432          7,377          5,795
                                                                 --------       --------       --------

Net income                                                       $ 15,039       $ 10,794       $ 14,856
                                                                 ========       ========       ========

Basic earnings per share:
     Net income                                                    $ 0.89         $ 0.58         $ 0.77
                                                                 ========       ========       ========
     Weighted average shares outstanding                           16,958         18,650         19,275
                                                                 ========       ========       ========

Diluted earnings per share:
     Net income                                                    $ 0.88         $ 0.57         $ 0.76
                                                                 ========       ========       ========
     Weighted average shares outstanding                           17,114         18,783         19,461
                                                                 ========       ========       ========
</TABLE>

          See accompanying notes to consolidated financial statements.

                                       A-3

<PAGE>

                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                           CONSOLIDATED BALANCE SHEETS

($ in thousands)
<TABLE>

<S>                                                                                   <C>                <C>
                                                                                             December 31,
                                                                                        1999               1998
ASSETS

Current assets:
     Cash and cash equivalents                                                         $20,064            $40,146
     Investments                                                                         4,120                  -
     Accounts receivable, less allowance for doubtful
        accounts of $224 in 1999 and $966 in 1998                                       23,273             21,400
     Other receivables                                                                   3,491              2,693
     Deferred income taxes                                                               1,066              2,330
     Prepaid expenses and other current assets                                           2,322                949
     Inventory                                                                           3,676              1,825
                                                                                      --------           --------
        Total current assets                                                            58,012             69,343
                                                                                      --------           --------

Property and equipment:
     Equipment, furniture and fixtures                                                  42,128             34,485
     Building and leasehold improvements                                                 2,092              2,073
                                                                                      --------           --------

                                                                                        44,220             36,558
     Less accumulated depreciation and
        amortization                                                                   (25,567)           (18,471)
                                                                                      --------           --------

        Property and equipment, net                                                     18,653             18,087
                                                                                      --------           --------

Other investments                                                                       18,963             11,026
Goodwill, at cost, net of amortization                                                 149,088            140,863
Other noncurrent assets                                                                  2,110                879
                                                                                      --------           --------
                                                                                      $246,826           $240,198
                                                                                      ========           ========
</TABLE>

          See accompanying notes to consolidated financial statements.

                                       A-4

<PAGE>

                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                     CONSOLIDATED BALANCE SHEETS (continued)

($ in thousands, except share data)
<TABLE>

<S>                                                                                   <C>                <C>
                                                                                            December 31,
                                                                                        1999               1998
LIABILITIES

Current liabilities:
     Current portion of long-term debt                                                 $ 1,763              $ 890
     Accounts payable                                                                    3,290              5,287
     Accrued distributions to minority interests                                         8,332              8,951
     Accrued expenses                                                                    7,108             12,051
                                                                                      --------           --------

         Total current liabilities                                                      20,493             27,179

Long-term debt, net of current portion                                                 103,797            100,987
Deferred income taxes                                                                    6,400              4,789
                                                                                      --------           --------

         Total liabilities                                                             130,690            132,955

Minority interest                                                                       19,454             17,493


STOCKHOLDERS' EQUITY

Preferred stock, $.01 par value, 1,000,000 shares
     authorized; none outstanding                                                           -                  -
Common stock, $0.01 par value, 40,000,000 shares
     authorized; 19,367,267 issued in 1999 and
     19,350,267 isssued in 1998                                                            194                194
Capital in excess of par value                                                          87,655             87,380
Accumulated earnings                                                                    33,654             18,615
Treasury stock, at cost, 2,875,300 shares in 1999
     and 1,845,200 shares in 1998                                                      (24,821)           (16,439)
                                                                                      --------           --------

         Total stockholders' equity                                                     96,682             89,750
                                                                                      --------           --------

                                                                                      $246,826           $240,198
                                                                                      ========           ========

</TABLE>

          See accompanying notes to consolidated financial statements.

                                       A-5

<PAGE>

                          PRIME MEDICAL SERVICES, INC.
                 CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
              For the years ended December 31, 1999, 1998 and 1997

($ in thousands, except share data)
<TABLE>

<S>                                      <C>          <C>          <C>          <C>          <C>          <C>          <C>
                                                                   Capital in    Accumulated

                                           Issued Common Stock      Excess of     Earnings          Treasury Stock
                                            Shares       Amount     Par Value     (Deficit)       Shares       Amount       Total
                                          ----------     ------    ----------      --------     ----------   ---------    --------

Balance, January 1, 1997                  19,078,933      $ 191     $ 83,271       $ (7,035)            -       $   -     $ 76,427

     Net income for the year                      -          -            -          14,856             -           -       14,856

     Exercise of stock options
        including tax benefit of
        $438 on non-qualifying
        exercises                            227,334          2          779             -              -           -          781
                                          ----------     ------    ----------      --------     ----------   ---------    --------
Balance, December 31, 1997                19,306,267        193       84,050          7,821             -           -       92,064

     Net income for the year                      -          -            -          10,794             -           -       10,794

     Tax benefits on exercised warrants           -          -         3,096             -              -           -        3,096

     Exercise of stock options
        including tax benefit of
        $140 on non-qualifying
        exercises                             44,000          1          234             -              -           -          235

     Purchase of treasury stock                   -          -            -              -      (1,845,200)    (16,439)    (16,439)
                                          ----------     ------    ----------      --------     ----------   ---------    --------

Balance, December 31, 1998                19,350,267        194       87,380         18,615     (1,845,200)    (16,439)     89,750

     Net income of the year                       -          -            -          15,039             -           -       15,039

     Issuance of put options                      -          -            73             -              -           -           73

     Issuance of warrants                         -          -            97             -              -           -           97

     Exercise of stock options
        including tax benefit of
        $18 on non-qualifying
        exercises                             17,000         -           105             -              -           -          105

     Purchase of treasury stock                   -          -            -              -      (1,030,100)     (8,382)     (8,382)
                                          ----------     ------    ----------      --------     ----------   ---------    --------

Balance, December 31, 1999                19,367,267      $ 194     $ 87,655       $ 33,654     (2,875,300)  $ (24,821)   $ 96,682
                                          ==========     ======    ==========      ========     ==========   =========    ========

</TABLE>

          See accompanying notes to consolidated financial statements.

                                       A-6

<PAGE>

                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES

                      CONSOLIDATED STATEMENTS OF CASH FLOWS

($ in thousands)
<TABLE>

<S>                                                                 <C>               <C>              <C>
                                                                               Years Ended December 31,
                                                                       1999              1998             1997
                                                                    ------------      -----------      ------------

CASH FLOWS FROM OPERATING ACTIVITIES:
     Fee and other revenue collected                                  $ 108,251         $ 98,649          $ 90,924
     Cash paid to employees, suppliers
         of goods and others                                            (52,144)         (39,748)          (31,685)
     Purchases of investments                                            (9,222)               -                 -
     Proceeds from sales and maturities of investments                    5,003                -                 -
     Interest received                                                    1,505            1,417               739
     Interest paid                                                       (9,353)          (7,261)           (7,521)
     Taxes paid                                                          (8,296)          (7,506)             (764)
                                                                    ------------      -----------      ------------

         Net cash provided by operating activities                       35,744           45,551            51,693
                                                                    ------------      -----------      ------------

CASH FLOWS FROM INVESTING ACTIVITIES:
     Purchase of equity investments and entities                        (23,580)               -           (20,217)
     Purchases of equipment and leasehold
         improvements                                                    (5,790)          (5,213)           (4,546)
     Proceeds from sales of equipment                                       207              224                30
     Distributions from investments                                       2,352            2,532             1,690
     Other                                                                  570              315                94
                                                                    ------------      -----------      ------------

         Net cash used in investing activities                          (26,241)          (2,142)          (22,949)
                                                                    ------------      -----------      ------------

CASH FLOWS FROM FINANCING ACTIVITIES:
     Payments on notes payable, exclusive of interest                    (1,403)         (80,484)          (50,328)
     Borrowings on notes payable                                          4,584          100,025            51,201
     Distributions to minority interest                                 (27,180)         (25,799)          (28,667)
     Debt issuance costs                                                      -           (4,417)                -
     Contributions by minority interest                                   2,636               72             2,381
     Exercise and issuance of stock options                                 160                9               343
     Purchase of treasury stock                                          (8,382)         (16,439)                -
                                                                    ------------      -----------      ------------

         Net cash used in financing activities                          (29,585)         (27,033)          (25,070)
                                                                    ------------      -----------      ------------

NET INCREASE (DECREASE) IN CASH
     AND CASH EQUIVALENTS                                               (20,082)          16,376             3,674

Cash and cash equivalents, beginning of period                           40,146           23,770            20,096
                                                                    ------------      -----------      ------------

Cash and cash equivalents, end of period                               $ 20,064         $ 40,146          $ 23,770
                                                                    ============      ===========      ============
</TABLE>

          See accompanying notes to consolidated financial statements.

                                       A-7

<PAGE>

                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                CONSOLIDATED STATEMENTS OF CASH FLOWS (continued)


($ in thousands)
<TABLE>

<S>                                                              <C>              <C>              <C>
                                                                            Years Ended December 31,
                                                                    1999             1998             1997
                                                                 ------------     ------------     ------------

Reconciliation of net income to net cash provided by
   operating activities:

Net income                                                          $ 15,039         $ 10,794         $ 14,856
Adjustments to reconcile net income to cash provided
     by operating activities:
         Minority interest in consolidated income                     24,508           24,790           25,041
         Depreciation and amortization                                10,848           10,476            9,911
         Provision for uncollectible accounts                            702              252              427
         Equity in earnings of affiliates                             (2,802)          (2,890)          (2,339)
         Debt issuance costs                                               -            4,417                -
         Provision for deferred income taxes                           2,875             (442)              68
         Write down of equipment                                       1,149                -                -
         Settlement of contingent liability                             (500)               -                -
         Release of contractual liability                             (1,140)               -                -
         Other                                                           (66)            (100)           1,159
     Changes in  operating  assets and  liabilities,
         net of effect of  purchase transactions:
             Investments                                              (4,120)               -                -
             Accounts receivable                                      (1,851)          (3,186)          (3,156)
             Other receivables                                        (1,424)            (910)             754
             Other assets                                             (2,585)          (1,244)            (602)
             Accounts payable                                         (2,665)             822              934
             Accrued expenses                                         (2,224)           2,772            4,640
                                                                 ------------     ------------     ------------

     Total adjustments                                                20,705           34,757           36,837
                                                                 ------------     ------------     ------------

Net cash provided by operating activities                           $ 35,744         $ 45,551         $ 51,693
                                                                 ============     ============     ============
</TABLE>

          See accompanying notes to consolidated financial statements.

                                       A-8

<PAGE>

                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                CONSOLIDATED STATEMENTS OF CASH FLOWS (continued)


($ in thousands)
<TABLE>

<S>                                                                         <C>            <C>             <C>
                                                                                     Years Ended December 31,
                                                                               1999           1998            1997
                                                                            -----------    ------------    ------------
SUPPEMENTAL INFORMATION OF NON-CASH
     INVESTING AND FINANCING ACTIVITIES:

At December 31, 1999, the Company had accrued distributions payable to
minority interests. The effect of this transaction was as follows:

         Current liabilities increased by                                      $ 8,332
         Minority interest decreased by                                          8,332

In 1999, the Company acquired, through a majority owned subsidiary 60% of the
outstanding stock of Horizon Vision Centers. This transaction is discussed
further in Note D. The acquired assets and liabilities were as follows:

         Current assets increased by                                               710
         Noncurrent assets increased by                                          3,057
         Goodwill increased by                                                   9,174
         Current liabilities increased by                                        1,489
         Noncurrent liabilities increased by                                       413
         Minority interest increased by                                            910

At December 31, 1998, the Company had accrued distributions payable to
minority interests. The effect of this transaction was as follows:

         Current liabilities increased by                                                      $ 8,951
         Minority interest decreased by                                                          8,951

In 1998, the Company recognized tax benefits associated with warrants
previously exercised. The effect of this was as follows:

         Current liabilities decreased by                                                        1,512
         Noncurrent liabilities decreased by                                                     1,584
         Stockholders' equity increased by                                                       3,096

In 1997, the Company acquired (1) additional ownership interests in 10
partnerships, (2) a 38.25% general partnership interest in a lithotripter
operation, (3) 100% of the stock of a lithotripter operator, and (4) 75%
equity interest in a trailer manufacturer. These transactions are discussed
further in Notes C and D. The acquired assets and liabilities were as
follows:

         Noncurrent assets increased by                                                                          4,041
         Goodwill increased by                                                                                  15,836
         Current liabilities increased by                                                                        1,343
         Minority interest decreased by                                                                            998

At December 31, 1997, the Company had accrued distributions payable to
minority interests. The effect of this transaction was as follows:

         Current liabilities increased by                                                                        8,655
         Minority interest decreased by                                                                          8,655

</TABLE>

          See accompanying notes to consolidated financial statements.

                                       A-9

<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


A.  ORGANIZATION AND OPERATION OF THE COMPANY

Prime Medical Services, Inc. ("Prime"), through its direct and indirect
wholly-owned subsidiaries, provides non-medical management services for
lithotripsy, refractive and prostatherapy operations. The Company
provides its services in 34 states. The Company also manufactures
trailers for major medical equipment manufacturers and mobile medical
service providers. References to the Company are to Prime and its
controlled and affiliated entities.

B.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Consolidation

The  consolidated  financial  statements  include  the  accounts  of Prime,  its
wholly-owned  subsidiaries,  entities more than 50% owned and partnerships where
Prime has control,  even though its ownership is less than 50%.  Investments  in
entities in which the Company's  investment is less than 50% ownership,  and the
Company  does not have  control,  are  accounted  for by the  equity  method  if
ownership  is between 20% - 50%, or by the cost method if ownership is less than
20%.  Through  December  31,  1999,  the  Company had  recognized  approximately
$675,000  in  undistributed  earnings  using  the  equity  method.  This  amount
represents  undistributed  earnings from entities, in which the Company owns 50%
or less, and does not exhibit control. All significant intercompany accounts and
transactions have been eliminated.

Cash Equivalents

The Company  considers as cash  equivalents  demand  deposits and all short-term
investments with an original maturity of three months or less.

Investments

The Company  classifies its investments in debt securities as trading securities
in  accordance  with  Statement  of  Financial  Accounting  Standards  No.  115,
Accounting  for  Certain  Investments  in Debt and  Equity  Securities.  Trading
securities are reported at fair value, with unrealized gains and losses included
in  earnings.  The  change in net  unrealized  holding  gain or loss on  trading
securities for the year ended December 31, 1999 was not material.

Property and Equipment

Property and equipment are stated at cost.  Major  betterments  are  capitalized
while normal maintenance and repairs are charged to operations.  Depreciation is
computed by the  straight-line  method using estimated  useful lives of three to
ten years.  Leasehold improvements are generally amortized over ten years or the
term of the lease,  whichever is shorter.  When assets are sold or retired,  the
corresponding cost and accumulated depreciation or amortization are removed from
the related accounts and any gain or loss is credited or charged to operations.

                                      A-10
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


B.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued)

Intangible Assets

The Company  records as goodwill the excess of the purchase  price over the fair
value  of the net  assets  associated  with  acquired  businesses.  Goodwill  is
amortized using the straight-line  basis over a period not to exceed twenty five
years for the refractive  segment and forty years for the  lithotripsy  segment.
Accumulated  amortization  at  December  31,  1999 and 1998 is  $18,155,000  and
$13,807,000,  respectively.  Goodwill is reviewed for impairment whenever events
or  changes  in  circumstances  indicate  that the  carrying  amount  may not be
recoverable.  If the sum of the expected future  undiscounted cash flows is less
than  the  carrying  amount  of the  goodwill,  a loss  is  recognized  for  the
difference between the discounted cash flows and carrying value of the goodwill.

Revenue Recognition

Revenues generated from management  services and the manufacture of trailers are
recognized as they are earned. The Company's  lithotripsy fee revenues are based
upon fees  charged for services to  hospitals,  commercial  insurance  carriers,
state and federal health care agencies, and individuals,  net of contractual fee
reductions.

Major Customers and Credit Concentrations

A  significant  portion of the  Company's  manufacturing  revenues are from four
customers.  For the years ended December 31, 1999 and 1998,  sales to these four
customers accounted for 71% of each year's manufacturing revenues.

Concentrations of credit risk with respect to receivables are limited due to the
wide variety of customers,  as well as their  dispersion  across many geographic
areas.  Other than as disclosed  below,  the Company does not consider itself to
have any  significant  concentrations  of credit  risk.  At December  31,  1999,
approximately 14% of accounts  receivable relate to units operating in Texas, 8%
relate  to units  located  in  Louisiana,  and 12%  relate to units  located  in
California.  At December  31,  1998,  approximately  17% of accounts  receivable
relate to units  operating in Texas,  11% relate to units  located in Louisiana,
and 10% relate to units located in California.

Income Tax

Deferred  tax  assets  and   liabilities  are  recognized  for  the  future  tax
consequences   attributable  to  differences  between  the  financial  statement
carrying  amounts of existing assets and  liabilities  and their  respective tax
bases and operating loss and tax credit  carryforwards.  Deferred tax assets and
liabilities  are measured  using enacted tax rates  expected to apply to taxable
income in the years in which  those  temporary  differences  are  expected to be
recovered  or settled.  The effect on deferred tax assets and  liabilities  of a
change in tax rates is  recognized  in income in the period  that  includes  the
enactment date.

                                      A-11
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


B.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued)

Long-Lived Assets

Long-lived  assets are reviewed  for  impairment  whenever  events or changes in
circumstances  indicate that the carrying amount may not be recoverable.  If the
sum of the  expected  future  undiscounted  cash flows is less than the carrying
amount of the asset, a loss is recognized,  for the difference  between the fair
value and carrying value of the asset.

Accounts Receivable

Accounts receivable are recorded based on revenues,  less allowance for doubtful
accounts and contractual adjustments.

Inventory

Inventory is stated at the lower of cost or market. Cost is determined using the
average cost method.  Certain  components that meet the Company's  manufacturing
requirements  are  only  available  from a  limited  number  of  suppliers.  The
inability to obtain components as required or to develop alternative sources, if
and as required in the future,  could  result in delays or  reduction in product
shipments,  which in turn could have a material  adverse effect on the Company's
manufacturing business, financial condition and results of operations.

Stock-Based Compensation

Upon adoption of Statement of Financial Accounting Standards No. 123, Accounting
for Stock-Based  Compensation  ("Statement 123"), in 1996, the Company continued
to measure compensation expense for its stock-based employee  compensation plans
using the intrinsic  value method  prescribed by APB Opinion No. 25,  Accounting
for Stock Issued to Employees.  The Company provides proforma disclosures of net
income and earnings per share as if the fair  value-based  method  prescribed by
Statement 123 had been applied in measuring compensation expense. (See Note J).

Debt Issuance Costs

The Company expenses debt issuance costs as incurred.

Estimates Used to Prepare Financial Statements

Management uses estimates and assumptions in preparing  financial  statements in
accordance with generally accepted  accounting  principles.  Those estimates and
assumptions  affect  the  reported  amounts  of  assets  and  liabilities,   the
disclosure of contingent  assets and liabilities,  and the reported revenues and
expenses.  Actual  results  could vary from the  estimates  that were assumed in
preparing the financial statements.

                                      A-12
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


B.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued)

Reclassification

Certain  reclassifications have been made to amounts presented in previous years
to be consistent with the 1999 presentation.

Earnings Per Share

Basic  earnings per share is based on the  weighted  average  shares outstanding
without any dilutive  effects  considered.  Diluted  earnings per share reflects
dilution from all contingently issuable shares,  including options and warrants.
A reconciliation of such earnings per share data is as follows:

(In thousands, except per share data)

                                              Net                 Per Share
For the year ended December 31, 1999         Income     Shares     Amounts
- ------------------------------------        -------     ------     -------

   Basic                                    $15,039     16,958       $0.89
                                                                   =======
   Effect of dilutive securities:
   Options                                       -         156
                                            -------     ------
   Diluted                                  $15,039     17,114       $0.88
                                            =======     ======     =======

For the year ended December 31, 1998
- ------------------------------------

   Basic                                    $10,794     18,650       $0.58
                                                                   =======
   Effect of dilutive securities:
   Options                                       -         133
                                            -------     ------
   Diluted                                  $10,794     18,783       $0.57
                                            =======     ======     =======

For the year ended December 31, 1997
- ------------------------------------

   Basic                                    $14,856     19,275       $0.77
                                                                   =======

   Effect of dilutive securities:
   Options                                       -         186
                                            -------     ------
   Diluted                                  $14,856     19,461       $0.76
                                            =======     ======     =======

Unexercised employee stock options and warrants to purchase 1,247,000, 1,708,000
and 841,000 shares of Prime common stock as of December 31, 1999, 1998 and 1997,
respectively,  were not included in the  computations of diluted EPS because the
option  exercise  prices were greater  than the average  market price of Prime's
common stock during the respective periods.

                                      A-13
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


C.  INVESTMENTS

Barnet Dulaney Eye Center

Effective  September  1, 1999 the Company  purchased a 60% interest in two laser
(refractive)   surgery  centers  operated  by  Barnet  Dulaney  Eye  Center  for
approximately  $8,807,000  in cash and a warrant to  purchase  29,000  shares of
Company common stock,  plus a contingent  earn-out  obligation to be paid at the
end of the first  year of  operations  after  the  acquisition.  The  contingent
earn-out  obligation  is based on the  operating  performance  of one of the two
surgery centers during the first year of operations after the acquisition.  This
investment is accounted for using the equity method.

Tenn-GA

In May 1997,  the  Company  acquired  a 38.25%  general  partner  interest  in a
partnership that provides mobile  lithotripsy  service in Tennessee and Georgia.
The purchase  price was cash of  $3,470,000.  This  investment  is accounted for
using the equity method.

Southern California

Effective  June 1, 1995,  the  Company  acquired a 32.5%  interest  in a limited
liability  company  that  operates a fixed site  lithotripter  near Los Angeles,
California. This investment is accounted for using the equity method.

Ohio and Louisiana Partnerships

In  December  1994,  the  Company  acquired  all  of  the  common  stock  of two
corporations.  Each  corporation is the general partner and holds an approximate
20% interest in a limited partnership which operates a mobile lithotripter. Ohio
Mobile Lithotripter, Ltd. operates a mobile lithotripter in Ohio. Arklatx Mobile
Lithotripter,   L.P.  operates  a  mobile   lithotripter  in  Louisiana.   These
investments are accounted for using the equity method.

American Physicians Service Group, Inc.

At December 31, 1999 and 1998,  the Company  owned 1,000 shares of common stock,
representing  less  than  1%,  of  the  outstanding  common  stock  of  American
Physicians Service Group, Inc. (APS). APS owned approximately 14% and 18% of the
outstanding  common  stock  of the  Company  at  December  31,  1999  and  1998,
respectively.  Two of the  Company's  six board members are also on the board of
APS.

The Company  occupies  approximately  6,700 square feet of office space owned by
APS. The Company also shares  certain  personnel  with APS. The monthly rent and
personnel cost is approximately  $10,000.  The Company purchased  treasury stock
shares through APS Financial Services,  Inc. (a wholly owned subsidiary of APS).
For the years ended December 31, 1999 and 1998, the Company paid  commissions of
approximately  $25,000  and  $100,000,  respectively,  to  acquire  420,100  and
1,845,000 shares,  respectively,  which management believes was competitive with
commissions charges by other firms offering such services.

                                      A-14
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


D.  ACQUISITIONS

Effective  September  1, 1999 the  Company  acquired,  through a majority  owned
acquisition subsidiary,  60% of the outstanding stock of Horizon Vision Centers,
Inc.  (Horizon).  Horizon  operates four laser  (refractive)  surgery centers in
California.  The  Company  paid  approximately  $10,866,000  in  cash  for  this
acquisition and has accounted for the  transaction  using the purchase method of
accounting.

Unaudited  proforma  combined  income data for the years ended December 31, 1999
and 1998 of the Company, the Horizon acquisition  discussed above and the equity
investment  acquisition  of the Barnet Dulaney Eye Center's  refractive  surgery
centers assuming they were effective January 1, 1998 is as follows:

($ in thousands, except per share data)

                                         1999                  1998
                                       --------              --------

Total revenues                         $121,710              $111,545
Total expenses                         $105,989              $100,522
                                       --------              --------

Net income                              $15,721               $11,023
                                       ========              ========

Diluted earnings per share                $0.92                 $0.59
                                       ========              ========

Effective  September 1, 1997, the Company  acquired a 75% equity  interest in AK
Associates,  LLC ("AK"), which provides  installation,  upgrade,  manufacturing,
refurbishment and repair services for major medical equipment  manufacturers and
mobile medical service providers. The purchase price was $4,761,000 in cash with
contingent  consideration  of $1,050,000  which was accrued at December 31, 1998
and paid in the first quarter of 1999. This  transaction was accounted for using
the purchase method of accounting.

Effective  June 1, 1997,  the Company  acquired  100% of the stock of  Executive
Medical  Enterprises,  Inc.  ("EME"),  which  operated  three  lithotripters  in
California, Oregon and Washington. The purchase price was $1,339,000 in cash and
potential   contingent   consideration  based  upon  the  performance  of  these
operations during 1998, 1999 and 2000. Contingent  consideration of $400,000 was
paid in 1998,  $843,000  was accrued at December  31, 1998 and paid in the first
quarter of 1999, and $54,000 was accrued  December 31, 1999. The transaction was
accounted for using the purchase method of accounting.

In January 1997,  the Company  purchased  additional  ownership  interests in 10
partnerships,  which the Company controls. The purchase price for the additional
ownership  interests was $10,510,000 in cash. These  transactions were accounted
for using the purchase method of accounting.

                                      A-15
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


E.  FAIR VALUE OF FINANCIAL INSTRUMENTS

Statement of Financial  Accounting  Standards  No. 107,  Disclosures  About Fair
Value of  Financial  Instruments  (Statement  107),  requires  that the  Company
disclose estimated fair values for its financial  instruments as of December 31,
1999 and 1998. The carrying amounts and fair values of the Company's significant
financial instruments are as follows:

                                    1999                        1998
                             ------------------         ------------------
                             Carrying    Fair           Carrying    Fair
($in thousands)               Amount     Value           Amount     Value
                             -------    -------         -------    -------
Financial assets:
Cash                         $20,064    $20,064         $40,146    $40,146
Investments                    4,120      4,120              -          -
Accounts receivable           23,273     23,273          21,400     21,400
Other receivables              3,491      3,491           2,693      2,693

Financial liabilities:
Debt                         105,560     97,560         101,877     92,603
Accounts payable               3,290      3,290           5,287      5,287

The following methods and assumptions were used by the Company in estimating its
fair value disclosures for financial instruments.

Cash

The carrying amounts for cash approximate fair value because they mature in less
than 90 days and do not present unanticipated credit concerns.

Investments

The carrying value of investments  approximates  fair value as they are reported
based on quoted market rates.

Accounts Receivable and Other Receivables

The carrying value of these receivables approximates the fair value due to their
short-term nature and historical collectibility.

Debt

The fair value at  December  31, 1999 and 1998 for the $100  million  fixed rate
senior subordinated notes was valued using the market rate of 10.2% and 10.456%,
respectively.  The  carrying  value of the debt  bearing  interest at prime rate
approximates fair value.

Accounts Payable

The carrying value of the payables approximates fair value due to the short-term
nature of the obligation.

                                      A-16
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


E.  FAIR VALUE OF FINANCIAL INSTRUMENTS (continued)

Limitations

Fair value  estimates  are made at a specific  point in time,  based on relevant
market  information and information about the financial  instrument.  Fair value
estimates are based on existing on balance sheet financial  instruments  without
attempting to estimate the value of anticipated future business and the value of
assets and  liabilities  that are not considered  financial  instruments.  Other
significant  assets and liabilities that are not considered  financial assets or
liabilities include deferred tax assets and liabilities, property and equipment,
equity investment in partnerships, goodwill, other noncurrent assets and accrued
expenses.  In addition,  the tax ramifications related to the realization of the
unrealized  gains  and  losses  can  have a  significant  effect  on fair  value
estimates and have not been considered in the aforementioned estimates.

F.  ACCRUED EXPENSES

Accrued expenses consist of the following:

                                                 December 31,
($ in thousands)                          1999               1998
                                        -------            -------

Legal fees                                 $291             $1,280
Accrued group insurance costs               193                206
Compensation and payroll
related expense                           1,393              2,958
Taxes, other than income taxes              343              1,301
Accrued interest                          2,247              2,192
Income taxes payable (receivable)          (146)             1,229
Deferred payments for acquisitions           54              1,950
Other                                     2,733                935
                                        -------            -------

                                         $7,108            $12,051
                                        =======            =======


                                      A-17
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


G.  INDEBTEDNESS

Long-term debt is as follows:

($ in thousands)                               December 31,
                                         1999               1998
                                       --------           --------
Interest Rates    Maturities

   8.75%          2000-2008            $100,808           $100,000
   Prime          2000-2003               4,464              1,715
   None           2000-2006                 162                162
   6%-9%          2000-2004                 126                 -
                                       --------           --------
                                       $105,560           $101,877
Less current portion of
        long-term debt                    1,763                890
                                       --------           --------
                                       $103,797           $100,987
                                       ========           ========

In March 1998, the Company completed an offering of an aggregate $100 million of
unsecured senior  subordinated  notes (the "Notes") due 2008. The issue price of
the notes was 99.50 with an 8.75% coupon.  Interest is payable  semi-annually on
April 1 and October 1, beginning October 1, 1998. The financing costs associated
with  this  offering  totaling  $4,418,000  were  expensed  during  1998  in the
accompanying  consolidated  statements of income. A portion of the proceeds from
the offering  were used to pay off the Company's $77 million of term loans under
its existing credit facility.

The Note Indenture restricts, among other things, the ability of the Company and
its Restricted Subsidiaries to incur additional indebtedness and issue preferred
stock, enter into sale and leaseback transactions, incur liens, pay dividends or
make certain other  restricted  payments,  apply net proceeds from certain asset
sales,  enter into certain  transactions  with affiliates,  merge or consolidate
with any other person, sell stock of subsidiaries and assign,  transfer,  lease,
convey or otherwise dispose of substantially all of the assets of the Company.

During 1998, the Company  amended its syndicated bank facility from $135 million
to $100  million.  The  facility  consists of a $100  million  revolving  credit
facility  bearing  interest  of  LIBOR + 1 to 2%,  maturing  in April  2003.  At
December  31,  1999,  the entire $100  million  revolving  credit  facility  was
undrawn.  At December  31, 1999,  interest on the  Company's  bank  facility was
7.385%.   The  assets  of  the  Company  and  the  stock  of  its   subsidiaries
collateralize the bank facility.

The stated principal repayments for all indebtedness as of December 31, 1999 are
payable as follows:

                                 ($ in thousands)
                        2000          $1,763
                        2001           1,845
                        2002           1,363
                        2003             280
                        2004             178
                      Thereafter     100,131

                                      A-18
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


H.  COSTS OF SERVICES AND GENERAL AND ADMINISTRATIVE EXPENSES

Costs of  services  and  general  and  administrative  expenses  consist  of the
following:

                                       Years Ended December 31,
                                  1999           1998           1997
($ in thousands)                -------        -------        -------

Salaries, wages and benefits    $16,230        $16,294        $15,779
Other costs of services           7,789          7,136          7,569
General and administrative        5,770          3,225          3,595
Legal and professional            2,167          2,551          2,064
Manufacturing costs              11,902          8,294          1,394
Other                             1,081          1,973          2,884
                                -------        -------        -------
                                $44,939        $39,473        $33,285
                                =======        =======        =======

I.  COMMITMENTS AND CONTINGENCIES

The Company is involved in various  claims and legal actions that have arisen in
the  ordinary  course of  business.  Management  believes  that any  liabilities
arising  from  these  actions  will not have a  material  adverse  effect on the
financial condition, results of operations or cash flows of the Company.

The Company sponsors a partially, self-insured group medical insurance plan. The
plan is  designed  to provide a  specified  level of  coverage,  with  stop-loss
coverage provided by a commercial insurer.  The Company's maximum claim exposure
is limited to $35,000 per person per policy  year.  At December  31,  1999,  the
Company   had  255   employees   enrolled  in  the  plan.   The  plan   provides
non-contributory   coverage  for   employees  and   contributory   coverage  for
dependents. The Company's contributions totaled $966,000, $623,000 and $351,000,
in 1999, 1998 and 1997 respectively.

J.  COMMON STOCK OPTIONS

1993 Stock Option Plan

The Company has elected to follow  Accounting  Principles  Board Opinion No. 25,
"Accounting   for  Stock   Issued  to   Employees"   ("APB   25")  and   related
Interpretations  in  accounting  for its  employee  stock  options.  The Company
provides  proforma  disclosures  of net income and  earnings per share as if the
fair-value  based  method  prescribed  by  Statement  123 had  been  applied  in
measuring  compensation expense. Under APB 25, because the exercise price of the
Company's employee stock options equals the market price of the underlying stock
on the date of grant, no compensation expense is recognized.

On October  12,  1993,  the  Company  adopted  the 1993 Stock  Option Plan which
authorizes  the  grant of up to  2,000,000  shares  to  certain  key  employees,
directors,  and consultants  and advisors to the Company.  Options granted under
the 1993 Stock Option Plan shall terminate no later than ten years from the date
the  option  is  granted,  unless  the  option  terminates  sooner  by reason of
termination of employment, disability or death.

                                      A-19
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


J.  COMMON STOCK OPTIONS (continued)

In June 1997,  the Company  adopted an  amendment  to the 1993 Stock Option Plan
that authorized an additional  500,000 shares. In June 1998, the Company adopted
an amendment to the 1993 Stock Option Plan that authorized an additional 750,000
shares.

A summary of the Company's stock option  activity,  and related  information for
the years ended December 31, follows:
<TABLE>
<S>                         <C>        <C>                 <C>        <C>                 <C>        <C>
                                       1999                           1998                           1997
                            --------------------------     --------------------------     --------------------------
                            Options   Weighted-Average     Options   Weighted-Average     Options   Weighted-Average
                             (000)     Exercise Price       (000)     Exercise Price       (000)     Exercise Price

Outstanding-beginning

of year                       1,892        $10.10           1,394        $11.04            1,228         $8.99

Granted                         695          7.56             825          8.63              428         11.94

Exercised                       (17)         5.10             (44)         3.73             (227)         1.51

Forfeited                      (276)        12.20            (283)        12.58              (35)        12.19
                             ------        ------           ------       ------            ------       ------

Outstanding-end of year       2,294         $9.10            1,892       $10.10             1,394       $11.04
                             ======        ======           ======       ======            ======       ======

Exercisable at end of year    1,137         $9.89              806       $10.74               466        $8.21

Weighted-average fair
   value of options
   granted during the year    $2.96           -              $3.40           -              $5.21           -
</TABLE>

The following table summarizes the Company's outstanding options at December 31,
1999:

<TABLE>
<S>                           <C>      <C>            <C>           <C>        <C>
                                         Outstanding Options        Exercisable Options
                                       -----------------------      -------------------
                                        Weighted
                                         Average      Weighted                 Weighted
                                        Remaining      Average                  Average
                              Options  Contractual    Exercise      Options    Exercise
Range of Exercise Prices       (000)      Life          Price        (000)      Price
- ------------------------      ------   -----------    --------      ------     --------

$0.25 - $4.12                    151    0.4 years       $0.37          151        $0.37
$4.13 - $8.25                    963    4.0 years        7.35          193         7.43
$8.26 - $12.37                   625    4.3 years        9.80          312        10.15
$12.38 - $16.50                  555    2.2 years       13.79          481        13.70
                              ------                                ------
                 Total         2,294                                 1,137
                              ======                                ======
</TABLE>

Proforma information  regarding net income and earnings per share is required by
Statement  123, and has been  determined as if the Company had accounted for its
employee stock options under the fair value method of that  Statement.  The fair
value for these options was estimated at the date of grant using a Black-Scholes
option pricing model with the following  weighted-average  assumptions for 1999,
1998 and 1997,  respectively:  risk-free  interest rates of 6.5%, 5.2% and 6.2%;
dividend  yields of 0%, 0% and 0%;  volatility  factors of the  expected  market
price of the Company's common stock of .44, .42 and .46; and a  weighted-average
expected life of the option of 4 years.

                                      A-20
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


J.  COMMON STOCK OPTIONS (continued)

The Black-Scholes option valuation model was developed for use in estimating the
fair value of traded  options which have no vesting  restrictions  and are fully
transferable.  In addition,  option valuation models require the input of highly
subjective  assumptions  including the expected stock price volatility.  Because
the  Company's  employee  stock  options  have   characteristics   significantly
different from those of traded  options,  and because  changes in the subjective
input assumptions can materially affect the fair value estimate, in management's
opinion,  the  existing  models do not  necessarily  provide a  reliable  single
measure of the fair value of its employee stock options.

For purposes of proforma disclosures, the estimated fair value of the options is
amortized to expense over the options'  vesting period.  The Company's  proforma
information follows (in thousands except for earnings per share information):

                                  1999           1998           1997
                                -------        -------        -------

Pro forma net income            $11,960         $7,817        $12,448
Pro forma earning per share:
   Basic                          $0.71          $0.42          $0.65
   Diluted                        $0.70          $0.42          $0.64

K.  LONG-LIVED ASSETS TO BE DISPOSED OF

In  accordance  with  Statement  of  Financial  Accounting  Standards  No.  121,
Accounting for the Impairment of Long-Lived  Assets and for Long-Lived Assets to
be Disposed Of,  equipment  which  management has both the ability and intent to
remove  from  service is reported in the  financial  statements  at the lower of
carrying  amount or fair  value  less  costs to sell.  During  1999 the  Company
approved  the removal from service of five  lithotripter  units.  Three of these
units were removed from service by the end of 1999 and the remaining two will be
removed from service within the first quarter of 2000.  These assets are held by
the lithotripsy segment. The customers of these units are or will be serviced by
other  equipment.  A loss of  approximately  $1.1 million was  recognized on the
write-down  to fair  value  less  costs  to sell  in the  caption  "nonrecurring
development,  impairment and other costs, net" of the accompanying  statement of
income. The minority interest portion of this loss was approximately $600,000.

L. INCOME TAXES

The Company files a consolidated tax return with its wholly owned  subsidiaries.
A substantial portion of consolidated income is not taxed at the corporate level
as it  represents  income from  partnerships.  Accordingly,  only the portion of
income from these partnerships attributable to the Company's ownership interests
is  included  in taxable  income in the  consolidated  tax return and  financial
statements.  The minority interest portion of this income is the  responsibility
of the individual partners.

                                      A-21
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


L.  INCOME TAXES (continued)

Income tax expense consists of the following:

                                       Years Ended December 31,
                                  1999           1998           1997
($ in thousands)                -------        -------        -------

Federal:
   Current                       $5,490         $6,404         $4,369
   Deferred                       2,875           (442)            68
State                             1,067          1,415          1,358
                                -------        -------        -------
                                 $9,432         $7,377         $5,795
                                =======        =======        =======


A reconciliation  of expected income tax (computed by applying the United States
statutory  income  tax rate of 35% to  earnings  before  income  taxes) to total
income  tax  expense  in the  accompanying  consolidated  statements  of  income
follows:

                                       Years Ended December 31,
                                  1999           1998           1997
($ in thousands)                -------        -------        -------

Expected federal income tax      $8,565         $6,360         $7,228
Change in beginning of year
   valuation allowance               -              -          (2,399)
State taxes                       1,067          1,415          1,358
Other                              (200)          (398)          (392)
                                -------        -------        -------
                                 $9,432         $7,377         $5,795
                                =======        =======        =======

The tax effects of temporary  differences that give rise to significant portions
of the deferred tax assets and deferred tax liabilities at December 31, 1999 and
1998 are presented below:

($ in thousands)                                 1999               1998
                                               -------            -------
Deferred tax assets:
   Capitalized costs                            $1,948             $2,381
   Loan origination fees amortizable
      for tax purposes                             949              1,267
   Accounts receivable, principally due
      to allowance for doubtful accounts            73                248
   Accrued expenses deductible for tax
      purposes when paid                           994              2,082
                                               -------            -------
   Total gross deferred tax assets               3,964              5,978
   Less valuation allowance                         -                  -
                                               -------            -------
   Net deferred tax assets                       3,964              5,978
                                               -------            -------


                                      A-22
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


L.  INCOME TAXES (continued)

($ in thousands)                                 1999               1998
                                               -------            -------
Deferred tax liabilities:
   Property and equipment, principally due
      to differences in depreciation           $  (99)            $  (166)
   Investments in affiliated entities,
      principally due to undistributed
      income                                   (2,329)             (2,703)
   Intangible assets, principally due to
      differences in amortization periods
      for tax purposes                         (6,870)             (5,568)
                                               -------            -------
      Total gross deferred tax liability       (9,298)             (8,437)
                                               -------            -------
Net deferred tax liability                     $(5,334)           $(2,459)
                                               =======            =======

There is no valuation allowance for deferred tax assets at December 31, 1999 and
1998. A decrease of $2,399,000  in 1997,  primarily  due to  utilization  of net
operating loss carryforwards was recorded in 1997.

In assessing  the  realizability  of deferred tax assets,  management  considers
whether it is more likely than not that some  portion or all of the deferred tax
assets will not be realized.  The ultimate realization of deferred tax assets is
dependent  upon the  generation of future  taxable  income during the periods in
which those temporary  differences become deductible.  Management  considers the
scheduled reversal of deferred tax liabilities, projected future taxable income,
and tax planning strategies in making this assessment.

Based upon the level of historical  taxable  income and  projections  for future
taxable  income  over the periods  which the  deductible  temporary  differences
reverse, management believes it is more likely than not the Company will realize
the benefits of these deductible differences at December 31, 1999.

M.  RELATED PARTY TRANSACTIONS

See Note C for related party transactions involving investments in affiliates.

N.  SEGMENT REPORTING

The  Company  has three  reportable  segments:  lithotripsy,  manufacturing  and
refractive.  The lithotripsy  segment provides services related to the operation
of  the  lithotripters,   including  scheduling,   staffing,  training,  quality
assurance,  maintenance,  regulatory  compliance  and  contracting  with payors,
hospitals and surgery centers. The manufacturing segment provides  manufacturing
services and  installation,  upgrade,  refurbishment and repair of major medical
equipment for mobile medical service providers. The refractive segment, which is
new in 1999,  provides  services related to the operations of refractive  vision
correction centers.  Other operating segments which do not meet the quantitative
thresholds for reportable segments include prostatherapy services.

                                      A-23
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


N.  SEGMENT REPORTING (continued)

The accounting  policies of the segments are the same as those described in Note
B,  the  summary  of  significant  accounting  policies.  The  Company  measures
performance  based on the pretax income or loss after  consideration of minority
interests  from  its  operating  segments,  which  do  not  include  unallocated
corporate general and administrative  expenses and corporate interest income and
expense.  Additionally,  certain  consolidated  entities  that are  reported  as
"corporate" own and operate lithotripsy equipment.  The revenue and depreciation
expense  related to this  equipment  is  included  in the  lithotripsy  segment.
However, the equipment is included in corporate assets.

The Company's segments are divisions that offer different services,  and require
different technology and marketing  approaches.  The majority of the lithotripsy
segment  is  comprised  of  acquired  entities,  as are  the  manufacturing  and
refractive segments.  The prostatherapy  segment was developed  internally.  The
presentation  of segments  for 1998 and 1997,  which  included  two segments for
medical  and  manufacturing,  have  been  recast  to  conform  to the  Company's
operating segments for 1999.

All of the  Company's  revenues are earned in the United  States and  long-lived
assets are located in the United  States.  The  Company  does not have any major
customers who account for more than 10% of its revenues.

                                      A-24
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


N.  SEGMENT REPORTING (continued)

($ in thousands)
                          Lithotripsy    Manufacturing    Refractive    Other
                          -----------    -------------    ----------    -----
1999
- ----
Revenue from
   external customers       $89,180         $17,527          $3,414     $2,053

Intersegment revenues            -              243              -          -

Interest income                 341              -               -           4

Interest expense                269              98             457         -

Depreciation and
   amortization               9,754             264             363        336

Segment profit               32,115           3,430             450        337

Segment assets              195,012          13,122          23,254      3,021

Investment in
   equity method
   investees                  8,814              -            9,375         -

Capital expenditures          4,367             161             548        298

1998
- ----
Revenue from
   external customers       $92,053         $11,066              -      $1,517

Intersegment revenues            -              255              -          -

Interest income                 444              -               -           3

Interest expense                235              38              -          -

Depreciation and
   amortization               9,899             223              -         252

Segment profit               35,484           1,142              -         209

Segment assets              203,653           9,916              -       2,628

Investment in
   equity method
   investees                 10,696              -               -          -

Capital expenditures          2,770           1,580              -         787






                                      A-25
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


N.  SEGMENT REPORTING (continued)

($ in thousands)
                          Lithotripsy    Manufacturing    Refractive    Other
                          -----------    -------------    ----------    -----
1997
- ----
Revenue from
   external customers       $93,113          $2,358              -        $508

Intersegment revenues            -              185              -          -

Interest income                 536              -               -          24

Interest expense                314              -               -          -

Depreciation and
   amortization               9,793              18              -          75

Segment profit               33,187             403              -          92

Segment assets              211,282           6,223              -       2,216

Investment in
   equity method
   investees                 10,658              -               -          -

Capital expenditures          3,741              23              -         732


The  following is a  reconciliation  of revenues  per above to the  consolidated
revenues per the consolidated statements of income:

                                            1999        1998        1997
($ in thousands)                          --------    --------    --------

Total revenues for reportable segments    $110,364    $103,374     $95,656

Other segment                                2,053       1,517         508

Elimination of intersegment revenues          (243)       (255)       (185)
                                          --------    --------    --------
Total consolidated revenues               $112,174    $104,636     $95,979
                                          ========    ========    ========


                                      A-26
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


N.  SEGMENT REPORTING (continued)

The following is a reconciliation of profit per above to income before taxes per
the consolidated statements of income:

                                                1999        1998        1997
($ in thousands)                               -------     -------     -------


Total profit for reportable segments           $35,995     $36,626     $33,590

Other segment                                      337         209          92

Unallocated corporate expenses:

   General and administrative                   (5,027)     (4,926)     (5,683)

   Net interest expense                         (7,424)     (7,226)     (6,983)

   Loan fees and stock offering costs             (566)     (4,978)       (360)

   Nonrecurring development and other costs        475      (1,617)          -

   Release of contractual obligation             1,140          -            -

   Other, net                                     (459)         83          (5)
                                               -------     -------     -------

   Unallocated corporate expenses total        (11,861)    (18,664)    (13,031)
                                               -------     -------     -------

Income before income taxes                     $24,471      $18,171    $20,651
                                               =======      =======    =======

The  following  is  a  reconciliation   of  segment  assets  per  above  to  the
consolidated assets per the consolidated balance sheets:

                                                1999        1998        1997
($ in thousands)                              --------    --------    --------

Total assets for reportable segments          $231,388    $213,569    $217,505

Other segment                                    3,021       2,628       2,216

Unallocated corporate assets                    12,417      24,001       5,184
                                              --------    --------    --------

Consolidated total                            $246,826    $240,198    $224,905
                                              ========    ========    ========




                                      A-27
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


N.  SEGMENT REPORTING (continued)

The reconciliation of the other significant items to the amounts reported in the
consolidated financial statements is as follows:

                                                 Eliminating
($ in thousands)          Segments    Corporate    Entries    Consolidated
                          --------    ---------    -------    ------------
1999

Interest income              $345       $1,250       $(90)        $1,505
Interest expense              824        8,674        (90)         9,408
Depreciation and
   amortization            10,717          131         -          10,848
Capital expenditures        5,374          416         -           5,790

1998

Interest income              $447       $1,007       $(37)        $1,417
Interest expense              273        8,233        (37)         8,469
Depreciation and
   amortization            10,374          102         -          10,476
Capital expenditures        5,137           76         -           5,213

1997

Interest income              $560         $180         -            $740
Interest expense              314        7,163         -           7,477
Depreciation and
   amortization             9,886           25         -           9,911
Capital expenditures        4,496           50         -           4,546

The amounts in 1999, 1998 and 1997 for interest income and expense, depreciation
and  amortization  and capital  expenditures  represent  amounts recorded by the
operations of the Company's corporate  functions,  which have not been allocated
to the segments.

O.  CONDENSED FINANCIAL INFORMATION REGARDING GUARANTOR SUBSIDIARIES

Condensed consolidating  financial information regarding the Company,  Guarantor
Subsidiaries and non-guarantor subsidiaries as of December 31, 1999 and 1998 and
for each of the  years in the  three-year  period  ended  December  31,  1999 is
presented below for purposes of complying with the reporting requirements of the
Guarantor  Subsidiaries.  Separate  financial  statements and other  disclosures
concerning each Guarantor  Subsidiary have not been presented because management
has determined that such information is not material to investors. The Guarantor
Subsidiaries  are  wholly-owned  subsidiaries  of the Company who have fully and
unconditionally guaranteed the Notes described in Note G.



                                      A-28
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                   Condensed Consolidating Statement of Income
                          Year Ended December 31, 1999

<TABLE>
<S>                                        <C>              <C>             <C>             <C>             <C>
                                            Prime Medical    Guarantor       Non-Guarantor   Eliminating     Consolidated
($ in thousands)                            Services, Inc.  Subsidiaries     Subsidiaries      Entries          Total
                                           --------------  --------------   --------------  --------------  --------------

Revenue:
     Lithotripsy:
         Fee revenues                                $ -        $ 20,303         $ 60,577             $ -        $ 80,880
         Management fees                               -           3,304            2,415               -           5,719
         Equity income                            32,763          18,799                -         (48,981)          2,581
                                           --------------  --------------   --------------  --------------  --------------
                                                  32,763          42,406           62,992         (48,981)         89,180
     Manufacturing                                     -               -           17,527               -          17,527
     Refractive                                      346             410            3,004            (346)          3,414
     Prostatherapy                                     -               -            1,834               -           1,834
     Other                                             -             219                -               -             219
                                           --------------  --------------   --------------  --------------  --------------
         Total revenue                            33,109          43,035           85,357         (49,327)        112,174
                                           --------------  --------------   --------------  --------------  --------------

Cost of services and general and
     administrative expenses:
         Lithotripsy                                   -           1,995           21,006               -          23,001
         Manufacturing                                 -               -           12,880               -          12,880
         Refractive                                    -               -            1,954               -           1,954
         Prostatherapy                                 -            (198)           1,483               -           1,285
         Other                                         -             165                -               -             165
         Corporate                                   248           4,779                -               -           5,027
         Nonrecurring development,
         impairment and other costs, net            (570)            173            1,024               -             627
                                           --------------  --------------   --------------  --------------  --------------
                                                    (322)          6,914           38,347               -          44,939
Depreciation and amortization                          5           5,216            5,627               -          10,848
                                           --------------  --------------   --------------  --------------  --------------
         Total operating expenses                   (317)         12,130           43,974               -          55,787
                                           --------------  --------------   --------------  --------------  --------------

Operating income                                  33,426          30,905           41,383         (49,327)         56,387
                                           --------------  --------------   --------------  --------------  --------------

Other income (deductions):
     Interest income                                 749             510              246               -           1,505
     Interest expense                             (9,111)            438             (735)              -          (9,408)
     Loan fees and stock offering costs             (492)            (74)               -               -            (566)
     Release of contractual obligation                 -           1,140                -               -           1,140
     Other, net                                     (662)            522               61               -             (79)
                                           --------------  --------------   --------------  --------------  --------------
         Total other income (deductions)          (9,516)          2,536             (428)              -          (7,408)
                                           --------------  --------------   --------------  --------------  --------------

Income before provision for income
     taxes and minority interest                  23,910          33,441           40,955         (49,327)         48,979

Minority interest in consolidated income               -               -                -          24,508          24,508

Provision for income taxes                         8,871             332              229               -           9,432
                                           --------------  --------------   --------------  --------------  --------------

Net income                                      $ 15,039        $ 33,109         $ 40,726       $ (73,835)       $ 15,039
                                           ==============  ==============   ==============  ==============  ==============

</TABLE>


                                      A-29
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                   Condensed Consolidating Statement of Income
                          Year Ended December 31, 1998

<TABLE>
<S>                                        <C>              <C>             <C>             <C>             <C>
                                            Prime Medical    Guarantor       Non-Guarantor   Eliminating     Consolidated
($ in thousands)                            Services, Inc.  Subsidiaries     Subsidiaries      Entries          Total
                                           ---------------  -------------   --------------  --------------  --------------

Revenue:
     Lithotripsy:
         Fee revenues                                $ -        $ 22,487         $ 61,392             $ -        $ 83,879
         Management fees                               -           3,126            2,158               -           5,284
         Equity income                            30,952          20,077                -         (48,139)          2,890
                                           --------------  --------------   --------------  --------------  --------------
                                                  30,952          45,690           63,550         (48,139)         92,053
     Manufacturing                                     -               -           11,066               -          11,066
     Prostatherapy                                     -               -            1,207               -           1,207
     Other                                             -             310                -               -             310
                                           --------------  --------------   --------------  --------------  --------------
         Total revenue                            30,952          46,000           75,823         (48,139)        104,636
                                           --------------  --------------   --------------  --------------  --------------

Cost of services and general and
     administrative expenses:
         Lithotripsy                                   -           3,977           18,697               -          22,674
         Manufacturing                                 -               -            9,204               -           9,204
         Prostatherapy                                 -               -              803               -             803
         Other                                         -             249                -               -             249
         Corporate                                   203           4,723                -               -           4,926
         Nonrecurring development,
         impairment and other costs, net           1,617               -                -               -           1,617
                                           --------------  --------------   --------------  --------------  --------------
                                                   1,820           8,949           28,704               -          39,473
Depreciation and amortization                          7           5,221            5,248               -          10,476
                                           --------------  --------------   --------------  --------------  --------------
         Total operating expenses                  1,827          14,170           33,952               -          49,949
                                           --------------  --------------   --------------  --------------  --------------

Operating income                                  29,125          31,830           41,871         (48,139)         54,687
                                           --------------  --------------   --------------  --------------  --------------

Other income (deductions):
     Interest income                                 735             305              377               -           1,417
     Interest expense                             (8,234)            (44)            (191)              -          (8,469)
     Loan fees and stock offering costs           (4,978)              -                -               -          (4,978)
     Other, net                                      (39)            331               12               -             304
                                           --------------  --------------   --------------  --------------  --------------
         Total other income (deductions)         (12,516)            592              198               -         (11,726)
                                           --------------  --------------   --------------  --------------  --------------

Income before provision for income
     taxes and minority interest                  16,609          32,422           42,069         (48,139)         42,961

Minority interest in consolidated income               -               -                -          24,790          24,790

Provision for income taxes                         5,815           1,470               92               -           7,377
                                           --------------  --------------   --------------  --------------  --------------

Net income                                      $ 10,794        $ 30,952         $ 41,977       $ (72,929)       $ 10,794
                                           ==============  ==============   ==============  ==============  ==============
</TABLE>


                                      A-30
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                   Condensed Consolidating Statement of Income
                          Year Ended December 31, 1997
<TABLE>
<S>                                        <C>              <C>             <C>             <C>              <C>
                                             Prime Medical    Guarantor      Non-Guarantor   Eliminating      Consolidated
($ in thousands)                            Services, Inc.   Subsidiaries    Subsidiaries      Entries           Total
                                           ---------------  --------------  --------------  --------------   --------------

Revenue:
     Lithotripsy:
         Fee revenues                                $ -         $ 20,863        $ 63,674             $ -         $ 84,537
         Management fees                               -            3,978           2,259               -            6,237
         Equity income                            27,386           18,587               -         (43,634)           2,339
                                           --------------   --------------  --------------  --------------   --------------
                                                  27,386           43,428          65,933         (43,634)          93,113
     Manufacturing                                     -                -           2,358               -            2,358
     Other                                             -              508               -               -              508
                                           --------------   --------------  --------------  --------------   --------------
         Total revenue                            27,386           43,936          68,291         (43,634)          95,979
                                           --------------   --------------  --------------  --------------   --------------

Cost of services and general and
     administrative expenses:
         Lithotripsy                                   -            4,646          20,735               -           25,381
         Manufacturing                                 -                -           1,743               -            1,743
         Other                                         -              478               -               -              478
         Corporate                                   567            5,116               -               -            5,683
                                           --------------   --------------  --------------  --------------   --------------
                                                     567           10,240          22,478               -           33,285
Depreciation and amortization                          7            5,157           4,747               -            9,911
                                           --------------   --------------  --------------  --------------   --------------
         Total operating expenses                    574           15,397          27,225               -           43,196
                                           --------------   --------------  --------------  --------------   --------------

Operating income                                  26,812           28,539          41,066         (43,634)          52,783
                                           --------------   --------------  --------------  --------------   --------------

Other income (deductions):
     Interest income                                   -              309             431               -              740
     Interest expense                             (7,160)             (52)           (265)              -           (7,477)
     Loan fees and stock offering costs             (360)               -               -               -             (360)
     Other, net                                        -             (128)            134               -                6
                                           --------------   --------------  --------------  --------------   --------------
                                           --------------   --------------  --------------  --------------   --------------
         Total other income (deductions)          (7,520)             129             300               -           (7,091)
                                           --------------   --------------  --------------  --------------   --------------

Income before provision for income
     taxes and minority interest                  19,292           28,668          41,366         (43,634)          45,692

Minority interest in consolidated income               -                -               -          25,041           25,041

Provision for income taxes                         4,436            1,282              77               -            5,795
                                           --------------   --------------  --------------  --------------   --------------

Net income                                      $ 14,856         $ 27,386        $ 41,289       $ (68,675)        $ 14,856
                                           ==============   ==============  ==============  ==============   ==============
</TABLE>


                                      A-31
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                      Condensed Consolidating Balance Sheet
                                December 31, 1999

<TABLE>
<S>                                          <C>              <C>            <C>             <C>              <C>
                                              Prime Medical    Guarantor      Non-Guarantor   Eliminating      Consolidated
($ in thousands)                              Services, Inc.  Subsidiaries    Subsidiaries      Entries           Total
                                             ---------------  -------------  --------------  --------------   -------------

ASSETS

Current assets:
     Cash                                          $ 2,043         $ 2,682        $ 15,339             $ -        $ 20,064
     Investments                                     4,120               -               -               -           4,120
     Accounts receivable, net                            -           3,069          20,204               -          23,273
     Other receivables                                 291           1,689           1,511               -           3,491
     Deferred income taxes                              94             972               -               -           1,066
     Prepaid expenses and other current assets          14           1,195           1,113               -           2,322
     Inventory                                           -               -           3,676                           3,676
                                             --------------  --------------  --------------  --------------   -------------
        Total current assets                         6,562           9,607          41,843               -          58,012
Property and equipment:
     Equipment, furniture and fixtures                   -           5,549          36,579               -          42,128
     Building and leasehold improvements                 -             498           1,594               -           2,092
                                             --------------  --------------  --------------  --------------   -------------
                                                         -           6,047          38,173               -          44,220
     Less accumulated depreciation
        and amortization                                 -          (4,514)        (21,053)              -         (25,567)
                                             --------------  --------------  --------------  --------------   -------------
        Property and equipment, net                      -           1,533          17,120               -          18,653

Investment in subsidiaries
     and other investments                         196,347          50,721               -        (228,105)         18,963
Goodwill, at cost, net of amortization                   -         139,989           9,099               -         149,088
Other noncurrent assets                                281             643           1,186               -           2,110
                                             --------------  --------------  --------------  --------------   -------------
                                                 $ 203,190       $ 202,493        $ 69,248      $ (228,105)      $ 246,826
                                             ==============  ==============  ==============  ==============   =============


LIABILITIES

Current liabilities:
     Current portion of long-term debt                 $ -             $ -         $ 1,763             $ -         $ 1,763
     Accounts payable                                   70           1,256           1,964               -           3,290
     Accrued expenses                                3,524           1,242          10,674               -          15,440
                                             --------------  --------------  --------------  --------------   -------------
        Total current liabilities                    3,594           2,498          14,401               -          20,493
Long-term debt, net of current portion             100,000             162           3,635               -         103,797
Deferred income taxes                                2,914           3,486               -               -           6,400
                                             --------------  --------------  --------------  --------------   -------------
        Total liabilities                          106,508           6,146          18,036               -         130,690

Minority interest                                        -               -               -          19,454          19,454

STOCKHOLDERS' EQUITY

Common stock                                           194               -               -               -             194
Capital in excess of par value                      87,655               -               -               -          87,655
Accumulated earnings                                33,654               -               -               -          33,654
Treasury stock                                     (24,821)              -               -               -         (24,821)
Subsidiary net equity                                    -         196,347          51,212        (247,559)              -
                                             --------------  --------------  --------------  --------------   -------------
        Total stockholders' equity                  96,682         196,347          51,212        (247,559)         96,682
                                             --------------  --------------  --------------  --------------   -------------
                                             --------------  --------------  --------------  --------------   -------------
                                                 $ 203,190       $ 202,493        $ 69,248      $ (228,105)      $ 246,826
                                             ==============  ==============  ==============  ==============   =============
</TABLE>


                                      A-32
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                      Condensed Consolidating Balance Sheet
                                December 31, 1998

<TABLE>
<S>                                          <C>              <C>            <C>             <C>              <C>
                                              Prime Medical    Guarantor      Non-Guarantor   Eliminating      Consolidated
($ in thousands)                              Services, Inc.  Subsidiaries    Subsidiaries      Entries           Total
                                             ---------------  -------------  --------------  --------------   -------------

ASSETS

Current assets:
     Cash                                         $ 15,798         $ 7,585        $ 16,763             $ -        $ 40,146
     Accounts receivable, net                            -           3,319          18,081               -          21,400
     Other receivables                                   -           2,693               -               -           2,693
     Deferred income taxes                           1,603             727               -               -           2,330
     Prepaid expenses and other current assets           -             456             493               -             949
     Inventory                                           -               -           1,825                           1,825
                                             --------------  --------------  --------------  --------------   -------------
        Total current assets                        17,401          14,780          37,162               -          69,343
Property and equipment:
     Equipment, furniture and fixtures                   -           5,301          29,184               -          34,485
     Building and leasehold improvements                 -             491           1,582               -           2,073
                                             --------------  --------------  --------------  --------------   -------------
                                                         -           5,792          30,766               -          36,558
     Less accumulated depreciation
        and amortization                                 -          (4,485)        (13,986)              -         (18,471)
                                             --------------  --------------  --------------  --------------   -------------
        Property and equipment, net                      -           1,307          16,780               -          18,087

Investment in subsidiaries
     and other investments                         178,611          28,038               -        (195,623)         11,026
Goodwill, at cost, net of amortization                   -         140,863               -               -         140,863
Other noncurrent assets                                105             488             286               -             879
                                             --------------  --------------  --------------  --------------   -------------
                                                 $ 196,117       $ 185,476        $ 54,228      $ (195,623)      $ 240,198
                                             ==============  ==============  ==============  ==============   =============


LIABILITIES

Current liabilities:
     Current portion of long-term debt                 $ -             $ -           $ 890             $ -           $ 890
     Accounts payable                                1,501           1,254           2,532               -           5,287
     Accrued expenses                                3,563           1,929          15,510               -          21,002
                                             --------------  --------------  --------------  --------------   -------------
        Total current liabilities                    5,064           3,183          18,932               -          27,179
Long-term debt, net of current portion             100,000             162             825               -         100,987
Deferred income taxes                                1,303           3,486               -               -           4,789
                                             --------------  --------------  --------------  --------------   -------------
        Total liabilities                          106,367           6,831          19,757               -         132,955

Minority interest                                        -               -               -          17,493          17,493

STOCKHOLDERS' EQUITY

Common stock                                           194               -               -               -             194
Capital in excess of par value                      87,380               -               -               -          87,380
Accumulated earnings                                18,615               -               -               -          18,615
Treasury stock                                     (16,439)              -               -               -         (16,439)
Subsidiary net equity                                    -         178,645          34,471        (213,116)              -
                                             --------------  --------------  --------------  --------------   -------------
        Total stockholders' equity                  89,750         178,645          34,471        (213,116)         89,750
                                             --------------  --------------  --------------  --------------   -------------
                                             --------------  --------------  --------------  --------------   -------------
                                                 $ 196,117       $ 185,476        $ 54,228      $ (195,623)      $ 240,198
                                             ==============  ==============  ==============  ==============   =============
</TABLE>


                                      A-33
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                 Condensed Consolidating Statement of Cash Flows
                                December 31, 1999

<TABLE>
<S>                                           <C>              <C>            <C>            <C>             <C>
                                               Prime Medical    Guarantor      Non-Guarantor  Eliminating     Consolidated
($ in thousands)                               Services, Inc.  Subsidiaries    Subsidiaries     Entries          Total
                                              ---------------  -------------  -------------  --------------  --------------

CASH FLOWS FROM OPERATING
     ACTIVITIES:
         Net cash provided by (used in)
              operating activities                $ (20,940)        $ 5,205       $ 51,479             $ -        $ 35,744
                                              --------------  --------------  -------------  --------------  --------------

CASH FLOWS FROM INVESTING
     ACTIVITIES:
     Purchase of investments and entities                 -         (13,451)       (10,129)              -         (23,580)
     Purchases of equipment and leasehold
         improvements                                     -          (1,193)        (4,597)              -          (5,790)
     Proceeds from sales of equipment                     -             167             40               -             207
     Distributions from subsidiaries                 15,407          17,424              -         (32,831)              -
     Investments                                          -           2,352              -               -           2,352
     Other                                                -               -            570               -             570
                                              --------------  --------------  -------------  --------------  --------------

         Net cash provided by (used in)
              investing activities                   15,407           5,299        (14,116)        (32,831)        (26,241)
                                              --------------  --------------  -------------  --------------  --------------

CASH FLOWS FROM FINANCING
     ACTIVITIES:
     Payments on notes payable exclusive of
         interest                                         -               -         (1,403)              -          (1,403)
     Borrowings on notes payable                          -               -          4,584               -           4,584
     Distributions to minority interest                   -               -              -         (27,180)        (27,180)
     Contributions by minority interest                   -               -          2,636               -           2,636
     Exercise and issuance of stock options             160               -              -               -             160
     Purchase of treasury stock                      (8,382)              -              -               -          (8,382)
     Distributions to equity owners                       -         (15,407)       (44,604)         60,011               -
                                              --------------  --------------  -------------  --------------  --------------

         Net cash provided by (used in)
                financing activities                 (8,222)        (15,407)       (38,787)         32,831         (29,585)
                                              --------------  --------------  -------------  --------------  --------------

NET INCREASE (DECREASE) IN CASH
     AND CASH EQUIVALENTS                           (13,755)         (4,903)        (1,424)              -         (20,082)

Cash and cash equivalents, beginning of period       15,798           7,585         16,763               -          40,146
                                              --------------  --------------  -------------  --------------  --------------

Cash and cash equivalents, end of period            $ 2,043         $ 2,682       $ 15,339             $ -        $ 20,064
                                              ==============  ==============  =============  ==============  ==============
</TABLE>


                                      A-34
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                 Condensed Consolidating Statement of Cash Flows
                                December 31, 1998

<TABLE>
<S>                                           <C>              <C>            <C>            <C>             <C>
                                               Prime Medical    Guarantor      Non-Guarantor  Eliminating     Consolidated
($ in thousands)                               Services, Inc.  Subsidiaries    Subsidiaries     Entries          Total
                                              ---------------  -------------  -------------  --------------  --------------

CASH FLOWS FROM OPERATING
     ACTIVITIES:
         Net cash provided by (used in)
              operating activities                $ (10,215)        $ 9,608       $ 46,158             $ -        $ 45,551
                                              --------------  --------------  -------------  --------------  --------------

CASH FLOWS FROM INVESTING
     ACTIVITIES:
     Purchases of equipment and leasehold
         improvements                                     -          (2,000)        (3,213)              -          (5,213)
     Proceeds from sales of equipment                     -             179             45               -             224
     Distributions from subsidiaries                 26,228          16,665              -         (42,893)              -
     Investments                                       (408)          2,940              -               -           2,532
     Other                                               22             166            127               -             315
                                              --------------  --------------  -------------  --------------  --------------

         Net cash provided by (used in)
              investing activities                   25,842          17,950         (3,041)        (42,893)         (2,142)
                                              --------------  --------------  -------------  --------------  --------------

CASH FLOWS FROM FINANCING
     ACTIVITIES:
     Payments on notes payable exclusive of
         interest                                   (79,000)             (5)        (1,479)              -         (80,484)
     Borrowings on notes payable                    100,000               -             25               -         100,025
     Distributions to minority interest                   -               -              -         (25,799)        (25,799)
     Debt issuance costs                             (4,417)              -              -               -          (4,417)
     Contributions by minority interest                   -               -             72               -              72
     Exercise and issuance of stock options               9               -              -               -               9
     Purchase of treasury stock                     (16,439)              -              -               -         (16,439)
     Distributions to equity owners                       -         (26,228)       (42,464)         68,692               -
                                              --------------  --------------  -------------  --------------  --------------

         Net cash provided by (used in)
                financing activities                    153         (26,233)       (43,846)         42,893         (27,033)
                                              --------------  --------------  -------------  --------------  --------------

NET INCREASE (DECREASE) IN CASH
     AND CASH EQUIVALENTS                            15,780           1,325           (729)              -          16,376

Cash and cash equivalents, beginning of period           18           6,260         17,492               -          23,770
                                              --------------  --------------  -------------  --------------  --------------

Cash and cash equivalents, end of period           $ 15,798         $ 7,585       $ 16,763             $ -        $ 40,146
                                              ==============  ==============  =============  ==============  ==============
</TABLE>


                                      A-35
<PAGE>
                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                 Condensed Consolidating Statement of Cash Flows
                                December 31, 1997

<TABLE>
<S>                                           <C>              <C>            <C>             <C>             <C>
                                               Prime Medical    Guarantor      Non-Guarantor   Eliminating     Consolidated
($ in thousands)                               Services, Inc.  Subsidiaries    Subsidiaries      Entries          Total
                                              ---------------  -------------  --------------  --------------  --------------

CASH FLOWS FROM OPERATING
     ACTIVITIES:
        Net cash provided by (used in)
             operating activities                  $ (9,441)       $ 14,879        $ 46,255             $ -        $ 51,693
                                              --------------  --------------  --------------  --------------  --------------

CASH FLOWS FROM INVESTING
     ACTIVITIES:
     Purchase of lithotripter entities                    -         (20,217)              -               -         (20,217)
     Purchases of equipment and leasehold
          improvements                                    -          (1,516)         (3,030)              -          (4,546)
     Proceeds from sales of equipment                     -              30               -               -              30
     Distributions from subsidiaries                  6,865          16,667               -         (23,532)              -
     Investments                                          -           1,690               -               -           1,690
     Other                                                -              94               -               -              94
                                              --------------  --------------  --------------  --------------  --------------
        Net cash provided by (used in)
             investing activities                     6,865          (3,252)         (3,030)        (23,532)        (22,949)
                                              --------------  --------------  --------------  --------------  --------------

CASH FLOWS FROM FINANCING
     ACTIVITIES:
     Payments on notes payable exclusive of
        interest                                    (47,750)         (1,100)         (1,478)              -         (50,328)
     Borrowings on notes payable                     50,000               -           1,201               -          51,201
     Distributions to minority interest                   -               -               -         (28,667)        (28,667)
     Contributions by minority interest                   -               -           2,381               -           2,381
     Exercise and issuance of stock options             343               -               -               -             343
     Distributions to equity owners                       -          (6,865)        (45,334)         52,199               -
                                              --------------  --------------  --------------  --------------  --------------

        Net cash provided by (used in)
             financing activities                     2,593          (7,965)        (43,230)         23,532         (25,070)
                                              --------------  --------------  --------------  --------------  --------------

NET INCREASE (DECREASE) IN CASH
     AND CASH EQUIVALENTS                                17           3,662              (5)              -           3,674

Cash and cash equivalents, beginning of period            1           2,598          17,497               -          20,096
                                              --------------  --------------  --------------  --------------  --------------

Cash and cash equivalents, end of period               $ 18         $ 6,260        $ 17,492             $ -        $ 23,770
                                              ==============  ==============  ==============  ==============  ==============
</TABLE>


                                      A-36
<PAGE>

                            ASSET PURCHASE AGREEMENT

                                      Among

                        PRIME LITHOTRIPSY SERVICES, INC.

                                    as Buyer,

                   RESTON HOSPITAL LITHOTRIPTER JOINT VENTURE

                                   as Seller,

                       RESTON LITHOTRIPSY ASSOCIATES, INC.

                  COLUMBIA ARLINGTON HEALTHCARE SYSTEM, L.L.C.

                                       and

                                ROBERT BALL, M.D.











                              Dated July 21, 1999


<PAGE>




                            ASSET PURCHASE AGREEMENT

         This Asset Purchase  Agreement  ("Agreement") is entered into as of the
21 day of July, 1999 ("Effective Date"), between and among PRIME LITHOTRIPSY
SERVICES,  INC., a New York corporation ("Buyer"),  RESTON HOSPITAL LITHOTRIPTER
JOINT VENTURE,  a Virginia general  partnership  ("Seller"),  RESTON LITHOTRIPSY
ASSOCIATES, INC., a Virginia corporation and partner in Seller ("RLA"), COLUMBIA
ARLINGTON  HEALTHCARE  SYSTEM,  L.L.C., a Virginia limited liability company and
partner in Seller ("CAHS"), and Robert Ball, M.D., an individual residing in the
Commonwealth of Virginia and partner in Seller ("ROBERT BALL, M.D.").

                             Preliminary Statements

         Seller owns a Dornier  Model HMT 482L  Extracorporeal  Shockwave  Renal
Lithotripter,  serial number 293, ("Lithotripter"),  leases the Lithotripter for
use to others, and provides related services to others.

         Buyer  desires to purchase  from  Seller and Seller  desires to sell to
Buyer the Lithotripter.

     RLA, CAHS and ROBERT BALL,  M.D. are the only partners of Seller,  and each
joins in the execution of this Agreement for the purposes set forth herein.

                             Statement of Agreement

         NOW,  THEREFORE,  in consideration of the premises and mutual covenants
contained  herein,  and  for  other  valuable  consideration,  the  receipt  and
sufficiency of which are acknowledged, the parties intending to be legally bound
hereby, agree as follows:

                                   ARTICLE I.

                           SALE AND PURCHASE OF ASSETS

         On the terms and subject to the conditions contained in this Agreement,
at the Closing (as hereinafter  defined),  Seller hereby agrees to sell, convey,
assign and  transfer to Buyer,  and Buyer agrees to purchase  from  Seller,  the
assets of Seller set forth  below,  free and clear of any  indebtedness,  liens,
encumbrances  or claims  by any  person or  entity.  The  assets of Seller to be
purchased by Buyer pursuant to this Agreement shall be collectively  referred to
herein as the "Assets," and are as follows:

     a. Property and Equipment. Lithotripter, operating manuals and the trailer.

     b.  Goodwill.  The  goodwill and  business  reputation  related to Seller's
business as of the Closing Date.

                                   ARTICLE II.

                         WARRANTIES, REPRESENTATIONS AND

              COVENANTS OF SELLER, RLA, CAHS AND ROBERT BALL, M.D.

         Each of the parties hereto other than Buyer (collectively, the "Control
Parties")  hereby  represents and warrants to Buyer as follows.  If a particular
representation and warranty is expressly stated below to be made, in whole or in
part,  about the  "Control  Parties,"  each  Control  Party will be deemed to be
making that  representation and warranty only about itself.  Representations and
warranties  expressly  about the "Seller"  will be deemed to be made jointly and
severally  by Seller  and each of the other  Control  Parties.  Otherwise,  each
Control Party (severally, and not jointly) is making each of the representations
and warranties in this Article II as to all matters  stated  therein  (including
without  limitation  paragraph h of this  Article  II).  Any  reference  in this
Agreement  to the "actual  knowledge"  of Seller  shall be defined as the actual
knowledge of Robert Ball, M.D., William A. Adams and A. Daniel Laurent, M.D. Any
reference in this  Agreement to the "actual  knowledge" of a particular  Control
Party  shall be  defined  (i) in the case of ROBERT  BALL,  M.D.,  as the actual
knowledge  of  Robert  Ball,  M.D.;  (ii) in the  case of  CAHS,  as the  actual
knowledge  of  William  A.  Adams;  and (iii) in the case of RLA,  as the actual
knowledge of A. Daniel Laurent, M.D.

                  a. Existence and Power.  Seller is a general  partnership duly
organized,  validly existing and in good standing under the laws of the State of
Virginia  and has all  requisite  power to own and operate  its  business as now
conducted  and as  proposed to be  conducted,  and to enter into and perform the
terms of this Agreement. RLA represents that it is a corporation duly organized,
validly  existing  and  in  good  standing  under  the  laws  of  its  state  of
incorporation,  and has all requisite  corporate power to enter into and perform
the terms of this  Agreement.  CAHS  represents  that it is a limited  liability
company duly organized,  validly existing and in good standing under the laws of
the Commonwealth of Virginia,  and has all requisite  limited  liability company
power to enter into and perform the terms of this Agreement.  ROBERT BALL, M.D.,
represents that he is an individual residing in the Commonwealth of Virginia and
possesses  all  necessary  power to enter  into and  perform  the  terms of this
Agreement.

                  b. Corporate Action.  The execution,  delivery and performance
of this Agreement and each other agreement,  document, instrument or certificate
required  to be  executed  by Seller or any other  Control  Party in  connection
herewith (collectively,  including this Agreement, the "Transaction Documents"),
are  authorized  by (as  applicable)  Seller's  or such  other  Control  Party's
respective shareholders,  members, directors,  governors,  partners, managers or
other  persons  having a right to direct its affairs,  and no further  action or
consent is needed by or from Seller or such other  Control  Party to make any of
the  Transaction  Documents  valid and binding upon Seller or such other Control
Party in accordance  with its terms.  Except with respect to Buyer,  each of the
Transaction  Documents  has been,  or prior to Closing will be, duly and validly
executed and delivered by Seller  and/or the other  Control  Parties (if a party
thereto) and  constitutes  a valid and binding  obligation  of Seller and/or the
other Control Parties,  enforceable  against each of them in accordance with its
terms.

     c. Consents and Approvals.  No action,  consent,  or approval of, or filing
with,  any  governmental  authority  is  required  by Seller or any of the other
Control Parties in connection with the execution, delivery or performance of any
of the Transaction Documents.

                  d. Title to Assets.  Seller  represents that it holds good and
marketable record and beneficial title and ownership to all of the Assets,  free
and  clear of any lien,  security  interest,  encumbrance  or claim and that the
Lithotripter  and  the  trailer  are in  reasonably  good  operating  condition.
Furthermore,  Seller  represents that, except for personnel and Permits (defined
below),  all the  assets of Seller  used in  connection  with the  operation  of
Seller's business as it is presently conducted, are included in the Assets to be
acquired by Buyer pursuant to this Agreement.

                  e. Licenses and Permits.  Schedule II(e) lists, to the best of
Seller's actual knowledge,  all third party and federal, state, county and local
governmental  licenses,  certificates and permits held by Seller and required in
connection with Seller's business activities or Seller's operation or use of the
Assets  (the  "Permits").  These  Permits  are not  assignable  and  will not be
transferred to Buyer at the Closing.  Seller represents that it is in compliance
with the terms and  conditions  of the  Permits,  except  to the  extent  that a
violation does not and cannot  reasonably be expected to have a material adverse
effect on the Assets. Seller further represents that it does not possess, nor is
it required to possess,  a  certificate  of public need to conduct the  Seller's
business as it is currently being conducted.

                  f. List of  Procedures.  Schedule II(f) lists the total number
of lithotripsy  procedures performed by Columbia Reston Hospital Center for each
of the calendar  years ending  December  31,  1996,  1997 and 1998,  and for the
period  beginning  January 1, 1999 and ending May 31, 1999.  Schedule II(f) also
lists the total number of Maryland residents who received  lithotripsy  services
at Columbia  Reston  Hospital  Center for the calendar year ending  December 31,
1998 and for the period  beginning  January 1, 1999 and  ending  June 29,  1999.
Seller  represents and warrants that Schedule II(f) fairly represents the number
of  lithotripsy  procedures  performed  on patients for the  indicated  periods.
Seller also represents and warrants that Schedule II(f) fairly  represents ^ the
number of Maryland residents receiving lithotripsy procedures at Columbia Reston
Hospital Center for the indicated periods.

                  g. No Adverse  Changes.  Since ^ May 31,  1999,  there has not
been any adverse change in the Assets,  business or operations of Seller,  other
than  changes in the  ordinary  course of business  that are not (when viewed in
conjunction with all other such changes) materially adverse.

                  h.  Claims  and  Litigation.  To the best of  Seller's  actual
knowledge, after due inquiry, there are no claims, actions, litigation, suits or
proceedings  pending  or  threatened  against  or  affecting  Seller,   Seller's
business, the Assets, or the transactions contemplated by this Agreement, at law
or in  equity,  at or before  any  federal,  state or  municipal  court or other
governmental department,  commission,  board, bureau, agency or instrumentality.
None of the  Control  Parties is subject  to or in default  with  respect to any
order, writ, injunction or decree of any federal, state, local or foreign court,
department,  agency or instrumentality  or arbitration  tribunal with respect to
the ownership,  operation or sale of the Assets or having a material and adverse
effect  on the  ability  of such  Control  Party  to  perform  their  respective
covenants and obligations set forth in this Agreement.

                  i. No Material Misstatements.  No representation,  warranty or
covenant of any of the Control Parties that is contained in this  Agreement,  or
in any Schedule or Exhibit hereto,  contains any untrue  statement of a material
fact or omits  any  material  fact  necessary  to make any such  representation,
warranty or covenant,  in light of the circumstances under which they were made,
not misleading.


<PAGE>



                                       37

                  j. No Violation; Compliance with Laws. The execution, delivery
and performance of each of the Transaction  Documents,  and the  consummation of
the  transactions  contemplated  hereby  and  thereby,  do not and  will not (i)
violate any law or regulation or any judicial or  administrative  order,  award,
judgment or decree  applicable  to Seller or the Assets  (other than  applicable
"bulk sales" laws); (ii) result in the creation of any lien,  security interest,
charge or encumbrance upon any of the Assets;  or (iii) violate or conflict with
any provision of Seller's organizational documents, excluding from the foregoing
clauses  (i) and (iii)  such  violations  that do not and cannot  reasonably  be
expected to have a material adverse effect on the Assets.

     k. No Known Breaches by Other Parties.  Each Control Party (severally,  and
not jointly) represents and warrants to Buyer that it has no actual knowledge of
any  breach  or  default  by any of the  other  Control  Parties  hereto  of any
representation,  warranty  or  covenant  contained  in any  of  the  Transaction
Documents.

                  l.  Representations  and Warranties True at Closing.  Each and
every  representation  and  warranty  by the Control  Parties  shall be true and
correct as of the  Closing  Date in all  respects,  regardless  of  whether  the
Closing  Date occurs on the date of  execution  of this  Agreement or some later
date pursuant to Section 7.1 hereof.

     m. Ownership of Seller; Equity Interest Owners of RLA. RLA, CAHS and ROBERT
BALL,  M.D.  each possess a  partnership  interest in Seller of 72%, 27% and 1%,
respectively.  RLA,  CAHS and ROBERT BALL,  M.D. are the only partners of Seller
and no other person or entity holds an equity interest of Seller. Schedule II(m)
sets  forth a list of each and every  person or  entity  that owns an  ownership
interest in RLA.

                  n.  Disclaimer of Warranties.  BUYER  ACKNOWLEDGES  AND AGREES
THAT EXCEPT AS OTHERWISE SPECIFICALLY PROVIDED HEREIN, SELLER HAS MADE AND MAKES
NO WARRANTIES EITHER EXPRESS OR IMPLIED,  WITH RESPECT TO THE ASSETS,  INCLUDING
WITHOUT  LIMITATION,  THE  IMPLIED  WARRANTY OF  MERCHANTABILITY  OR THE IMPLIED
WARRANTY OF FITNESS FOR A PARTICULAR  PURPOSE.  BUYER FURTHER  ACKNOWLEDGES  AND
AGREES THAT EXCEPT AS OTHERWISE  SPECIFICALLY  PROVIDED  HEREIN,  THE ASSETS ARE
BEING TRANSFERRED AS IS, WHERE IS, AND WITH ALL FAULTS.

                                  ARTICLE III.

                         WARRANTIES, REPRESENTATIONS AND

                               COVENANTS OF BUYER

         Buyer  hereby  represents,  warrants to, and  covenants  with Seller as
follows:

     a. Corporate  Existence.  Buyer is a corporation  duly  organized,  validly
existing  in good  standing  under the laws of the  State of New York.  Buyer is
authorized  to  transact  business  in  Virginia,  and Buyer  has all  requisite
corporate  power to own and operate its  business  and to enter into and perform
the terms of this Agreement.

                  b. Corporate Action.  The execution,  delivery and performance
of each  Transaction  Document to which Buyer is a party have been authorized by
all necessary  corporate  action,  and such Transaction  Document  constitutes a
valid and binding  obligation upon Buyer,  enforceable  against it in accordance
with its terms.

     c. No Violation.  The execution,  delivery and performance by Buyer of each
Transaction  Document to which  Buyer is a party,  and the  consummation  of the
transactions  contemplated  herein and therein,  do not and will not violate any
law or regulation or any judicial or administrative  order,  award,  judgment or
decree applicable to Buyer.

                                   ARTICLE IV.

                           PURCHASE PRICE AND PAYMENT

         The total purchase price and consideration for the Assets to be sold to
Buyer pursuant to this Agreement shall be $2,400,000.00, to be paid to Seller at
the Closing in immediately available funds.

                                   ARTICLE V.

                          ALLOCATION OF PURCHASE PRICE

         Seller and Buyer hereby agree to allocate the purchase  price among the
Assets, the  non-competition  covenant set forth in Article VIII hereof, and the
other agreements  entered into in connection with this Agreement,  in accordance
with the allocations set forth on Schedule V hereto.  Such allocations have been
mutually  determined by the parties at arm's length and the parties hereto agree
to use such allocations for federal income tax purposes.

                                   ARTICLE VI.

                                   LIABILITIES

         Buyer is not  assuming any debts,  liabilities  or  obligations  of any
kind, of Seller or any Control  Parties,  or otherwise,  in connection  with the
purchase of the  Assets,  the Closing or the  consummation  of the  transactions
contemplated  by this Agreement.  All claims,  liabilities or obligations of, or
against, Seller and each other Control Party (including, without limitation, any
and all federal,  state or other  governmental  taxes and related  liabilities),
whether accrued, absolute, contingent or otherwise, and whether due or to become
due, fixed or contingent, known or unknown, will be and remain the liability and
responsibility of Seller or such other Control Party, as applicable.  SELLER AND
EACH OTHER CONTROL PARTY AGREE TO HOLD BUYER AND THE BUYER  INDEMNIFIED  PARTIES
HARMLESS  FOR SAME  AND  AGREE TO  DEFEND  AND  INDEMNIFY  BUYER  AND THE  BUYER
INDEMNIFIED  PARTIES  IN  CONNECTION  WITH  ANY  SUCH  CLAIMS,  LIABILITIES,  OR
OBLIGATIONS  ASSERTED  AGAINST  BUYER,  PURSUANT TO THE PROVISIONS OF ARTICLE IX
HEREOF.

                                  ARTICLE VII.

                                     CLOSING

         Section 7.1 Closing.  The purchase,  sale and transfer of possession of
the Assets  (the  "Closing")  shall take place at the  offices of Grad,  Logan &
Klewans, P.C., 1421 Prince Street, Suite 320, Alexandria, Virginia 22314, on the
date of execution of this  Agreement,  or at such other place,  date and time as
the parties  hereto  shall  mutually  agree upon in  writing.  The date that the
Closing occurs is referred to herein as the "Closing Date."

         Section 7.2 Action by Seller. At the Closing,  Seller shall execute (as
applicable),  acknowledge and deliver, or cause to be executed and delivered, to
Buyer, the following:

          a.  Assignment  and Warranty Bill of Sale, in  substantially  the form
     attached hereto as Exhibit A, covering all Assets.

                  b.  Executed  copies of  non-compete  agreements,  in the form
attached  hereto as Exhibit B, for each of the sixteen  shareholders  in RLA who
does not own an existing,  competing  interest and is not engaged in a competing
activity.

                  c.  Executed  copies of  non-compete  agreements,  in the form
attached  hereto as Exhibit C, for each of the two  shareholders in RLA who owns
an existing, competing interest or engages in a competing activity.

                  d.  Closing  certificate  executed  by an  authorized  general
partner of Seller stating that all  representations and warranties of Seller set
forth in any Transaction  Document are true, complete and correct at the time of
Closing,  and that  between the date hereof and the  Closing,  there has been no
material change in the condition of the Assets or Seller's business.

                  e.  Closing  certificate  executed  by  the  President  of RLA
stating  that  all  representations  and  warranties  of RLA  set  forth  in any
Transaction  Document are true,  complete and correct at the time of Closing and
that RLA has no actual knowledge of a breach of a representation and warranty by
either of the other Control Parties.

                  f. Closing  certificate  executed by an authorized  officer of
CAHS stating that all  representations  and  warranties of CAHS set forth in any
Transaction  Document are true,  complete and correct at the time of Closing and
that CAHS has no actual knowledge of a breach of any representation and warranty
by either of the other Control Parties.

          g. Closing certificate  executed by ROBERT BALL, M.D. stating that all
     representations  and  warranties  of  ROBERT  BALL,  M.D.  set forth in any
     Transaction  Document are true, complete and correct at the time of Closing
     and that  ROBERT  BALL,  M.D.  has no actual  knowledge  of a breach of any
     representation and warranty by either of the other Control Parties.

         Section 7.3 Action by Buyer.  At the Closing,  Buyer shall  execute (as
applicable),  acknowledge and deliver, or cause to be executed and delivered, to
Seller, the following:

          a. The cash sum in the amount of $2,400,000.00  pursuant to Article IV
     hereof, by wire transfer to an account designated by Seller.

                  b. Closing certificate  executed by the President or Secretary
of Buyer stating that all  representations  and warranties of Buyer set forth in
any Transaction Document are true, complete and correct at the time of Closing.

         Section 7.4 Further Assurances. At any time and from time to time after
the Closing,  Seller and the other  Control  Parties  shall,  at the  reasonable
request of Buyer, execute and deliver or cause to be executed and delivered, all
such bills of sale,  assignments,  consents,  documents  (including documents of
title  with  respect  to  any  titled  property   included  among  the  Assets),
certificates  and  instruments,  and take or cause  to be taken  all such  other
action, as may be reasonably deemed necessary or desirable in order to put Buyer
in actual  possession and operating  control of the Assets, or to more fully and
effectively vest in Buyer or to confirm in buyer full right,  title and interest
to the Assets, free and clear of all liens and security interests, in accordance
with this  Agreement,  or to assist Buyer in exercising  its rights with respect
thereto, or otherwise to carry out the intents and purposes of this Agreement.

         Section 7.5  Conditions  to Closing.  In the event the Closing does not
occur on the date of  execution  of this  Agreement,  it shall be a condition to
Closing by each party that (i) Buyer,  Prime Medical Services,  Inc., a Delaware
corporation ("Prime"),  or one of Prime's subsidiaries shall have entered into a
Lithotripsy  Agreement  with  CAHS  pursuant  to which  Buyer or one of  Prime's
subsidiaries  will provide  lithotripsy and related  services at Reston Hospital
Center;  (ii) all actions required to be taken by the other party or parties set
forth in this  Article  VII shall  have been  taken at or prior to the  Closing;
(iii) all  documents  to be  delivered  pursuant  to this  Article  VII shall be
satisfactory in form and substance to such party and its counsel;  and (iv) such
party or its counsel shall have received copies of all documents, instruments or
certificates,  executed  or  certified,  whichever  may  be  appropriate,  as is
required by this Article VII. For purposes of this Section, all forms of closing
documents  attached to this Agreement are hereby stipulated by the parties to be
in satisfactory form.

                                  ARTICLE VIII.

                            NON-COMPETITION COVENANTS

         Section 8.1 Seller,  RLA and Ball,  severally  and not jointly,  hereby
agrees that,  until the  expiration  of its  respective  Restriction  Period (as
defined for each below), it will not directly or indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation of which they own less than five percent of any class of outstanding
securities), or as a principal, agent, employer, advisor, consultant, co-partner
or in any individual or  representative  capacity  whatever,  either for its own
benefit or for the benefit of any other person, firm or corporation, without the
prior written  consent of Buyer,  commit any of the following  acts,  which acts
shall be considered violations of this covenant not to compete:

                  (a)  Lithotripsy  Services.  Except as  permitted  pursuant to
Section  8.3  below,   directly  or  indirectly  provide  lithotripsy  services,
including  without  limitation,   patient  lithotripsy   services,   lithotripsy
management  services,  Lithotripter  leasing,  or similar  lithotripsy  services
(collectively,  "Lithotripsy  Services"),  anywhere  within 50 miles of Columbia
Reston Hospital Center, Reston, Virginia.

                  (b)  Interference  with  Business  Relationships.  Directly or
indirectly request or advise any patient or physician or any other person,  firm
or  corporation  having a  business  relationship  with  Buyer or any of Buyer's
affiliates  (or having a past  business  relationship  with Seller) to withdraw,
curtail,  or cancel its business with Buyer or Buyer's  affiliates,  as the case
may be; or

                  (c) Solicitation of Employees. Directly or indirectly hire any
employee of Buyer or any of Buyer's affiliates or induce or attempt to influence
any  employee  of Buyer or any of Buyer's  affiliates  to  terminate  his or her
employment with such entity.

         Section 8.2 So long as Buyer,  its affiliates,  assignees or successors
continues to provide Lithotripsy Services to Reston Hospital Center, CAHS hereby
agrees that, until the expiration of its Restriction  Period (as defined below),
it will not  directly or  indirectly,  ^ whether  through any kind of  ownership
(other than ownership of securities of a publicly held corporation of which they
own less than five percent of any class of  outstanding  securities),  ^ through
the  actions of its  member  HCA Health  Services  of  Virginia,  Inc.,  or as a
principal, agent, employer, advisor, consultant, co-partner or in any individual
or  representative  capacity  whatever,  either  for its own  benefit or for the
benefit of any other  person,  firm or  corporation,  without the prior  written
consent  of  Buyer,  commit  any of the  following  acts,  which  acts  shall be
considered violations of this covenant not to compete:

                  (a)  Lithotripsy  Services.  Except as otherwise  permitted in
this  subparagraph  (a) and Section 8.3 below,  directly or  indirectly  provide
Lithotripsy  Services  anywhere within the Restriction  Area (defined below) for
the applicable  period. The restriction set forth in this subparagraph (a) shall
not apply to any facility in which CAHS, or any affiliate or successor  thereof,
acquires  after the  Closing a  beneficial  interest  that,  at the time of such
acquisition, provides Lithotripsy Services to the general public and for which ^
annual  gross  revenues  from  Lithotripsy  Services  do not exceed 5% of ^ such
facility's  ^  annual  gross  revenues.  For  purposes  of this  Agreement,  the
"Restriction  Area"  shall mean that area  within the  Commonwealth  of Virginia
which is defined by a driving  distance  radius from  Columbia  Reston  Hospital
Center,  Reston,  Virginia  of 50 miles  for the first  year of the  Restriction
Period, 30 miles for the second year of the Restriction  Period and 20 miles for
each of the third, fourth and fifth years of the Restriction Period.

                  (b)  Interference  with  Business  Relationships.  Directly or
indirectly request or advise any patient or physician or any other person,  firm
or  corporation  having a  business  relationship  with  Buyer or any of Buyer's
affiliates  (or having a past  business  relationship  with Seller) to withdraw,
curtail,  or cancel its business with Buyer or Buyer's  affiliates,  as the case
may be; or

                  (c) Solicitation of Employees. Directly or indirectly hire any
employee of Buyer or any of Buyer's affiliates or induce or attempt to influence
any  employee  of Buyer or any of Buyer's  affiliates  to  terminate  his or her
employment with such entity.

         Section  8.3  Medical  Judgment.  Nothing  in this  Agreement  shall be
construed to limit or infringe upon the professional medical judgment or ability
to practice medicine of any party hereto that is a physician (including, but not
limited to, the selection of appropriate  facilities  for medical care),  and no
exercise of such a party's professional medical judgment or act constituting the
practice of medicine shall be considered a violation of this Agreement.

         Section 8.4 Restriction  Period.  For purposes of this  Agreement,  the
"Restriction  Period" shall begin on the Effective  Date and continue until five
(5) years after the Effective Date.

         Section 8.5  Affiliates.  For purposes of this  Agreement,  the Buyer's
affiliates  shall  include  Prime,  and each of Prime's and  Buyer's  respective
current and future  (throughout  the Restriction  Period),  direct and indirect,
subsidiaries and affiliates.

         Section 8.6 Restrictions  Reasonable.  RLA, CAHS and Ball have reviewed
and carefully  considered the  provisions of this Article VIII and,  having done
so, agree that the  restrictions  set forth  herein (a) are fair and  reasonable
with respect to time,  geographic area and scope, (b) are not unduly burdensome,
and (c) are reasonably  required for the protection of the respective  interests
of the parties.

         Section  8.7  Equitable  Relief.  RLA,  CAHS and Ball each agree that a
violation on its part of any covenant  contained in this Article VIII will cause
the  other  parties  irreparable  damage  for  which  remedies  at  law  may  be
insufficient,  and for that  reason,  each agrees that the other  parties  shall
each,  independently,  be entitled as a matter of right to  equitable  remedies,
including  specific  performance and injunctive relief,  therefor.  The right to
specific  performance and injunctive  relief shall be cumulative and in addition
to whatever other remedies,  at law or in equity,  may be available,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX.

                            INDEMNIFICATION OF BUYER

         Section 9.1  Indemnification  of Buyer. For a period of two years after
the Closing  Date,  Seller and each of the other  Control  Parties,  jointly and
severally, but subject to the limitation set forth below, agree to indemnify and
hold Buyer,  Prime and each of Prime's and Buyer's  respective  representatives,
officers,  directors,  employees,  and  affiliates  (collectively,   the  "Buyer
Indemnified  Parties")  harmless  from and against any and all damages,  losses,
claims,  liabilities,  demands,  charges, suits, penalties,  costs, and expenses
(including court costs and reasonable  attorneys' fees and expenses  incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Buyer  Indemnified  Parties may sustain,
arising  out of, or with  respect to, (i) any breach or default by Seller or any
of  the  other  Control  Parties  of any  of  the  representations,  warranties,
covenants  or  agreements  contained  in  any  Transaction  Document,  (ii)  any
obligations or any  liabilities to any finder,  broker or sales agent engaged or
retained by Seller or another  Control  Party,  (iii) any debts,  liabilities or
obligations of Seller (iv) any debts,  liabilities or obligations of any Control
Parties with respect to the Assets or business  conducted  utilizing the Assets,
(v) any act or omission by Seller that  occurred  prior to the Closing,  or (vi)
any act or omission by any of the Control  Parties that relates to the Assets or
business  conducted  utilizing  the Assets and  occurred  prior to the  Closing.
Regardless of anything  contained in this  Agreement to the  contrary,  Seller's
indemnification  liability  shall be limited to an amount  equal to the purchase
price  and  each of the  Control  Parties'  indemnification  liability  shall be
limited to an amount equal to $24,000.00  for ROBERT BALL,  M.D.,  $1,728,000.00
for RLA and $648,000.00 for CAHS, and in no case shall the collective  liability
of the Seller and Control Parties be greater than the purchase price.

         Section 9.2 Defense of Third-Party  Claims. A Buyer  Indemnified  Party
shall give prompt written notice to Seller and the other Control  Parties of the
commencement  or  assertion of any  third-party  action in respect of which such
Buyer Indemnified Party shall seek indemnification  hereunder. Any failure so to
notify  Seller and the other Control  Parties  shall not relieve  Seller and the
other  Control  Parties  from any  liability  that  they may have to such  Buyer
Indemnified  Party under this Article IX, unless the failure to give such notice
materially and adversely prejudices Seller and the other Control Parties. Seller
and the other  Control  Parties  shall  have the right to assume  control of the
defense of,  settle,  or otherwise  dispose of such  third-party  action on such
terms as they deem appropriate; provided, however, that:

          (a) The Buyer Indemnified Party shall be entitled, at his, her, or its
     own expense, to participate in the defense of such third-party action;

                  (b)  Seller and the other  Control  Parties  shall  obtain the
prior written approval of the Buyer Indemnified  Party, which approval shall not
be  unreasonably  withheld  or  delayed,  before  entering  into or  making  any
settlement,  compromise,  admission,  or  acknowledgment of the validity of such
third-party  action or any liability in respect  thereof if, pursuant to or as a
result of such settlement, compromise, admission, or acknowledgment,  injunctive
or other equitable relief would be imposed against the Buyer  Indemnified  Party
or  if,  in  the  reasonable  opinion  of  the  Buyer  Indemnified  Party,  such
settlement,  compromise,  admission,  or  acknowledgment  would  have a material
adverse effect on its business or, in the case of a Buyer  Indemnified Party who
is a natural person, on his or her assets or interests;

                  (c) Seller and the other Control  Parties shall not consent to
the entry of any judgment or enter into any settlement  that does not include as
an  unconditional  term thereof the giving by each claimant or plaintiff to each
Buyer  Indemnified  Party of a release  from all  liability  in  respect of such
third-party action;

                  (d) Seller and the other Control Parties shall not be entitled
to control  (but shall be  entitled to  participate  at their own expense in the
defense  of),  and the Buyer  Indemnified  Party  shall be entitled to have sole
control   over,   the  defense  or   settlement,   compromise,   admission,   or
acknowledgment  of any  third-party  action (i) as to which Seller and the other
Control  Parties fail to assume the defense  within a reasonable  length of time
after  giving  notice to Seller  and the other  Control  Parties  or (ii) to the
extent the  third-party  action seeks an order,  injunction,  or other equitable
relief  against  the  Buyer  Indemnified  Party  which,  if  successful,   would
materially  adversely  affect the  business,  operations,  assets,  or financial
condition of the Buyer  Indemnified  Party;  provided,  however,  that the Buyer
Indemnified  Party  shall  make  no  settlement,   compromise,   admission,   or
acknowledgment  which would give rise to  liability on the part of Seller or the
other Control  Parties without the prior written consent of Seller and the other
Control Parties;

                  (e) Seller and the other  Control  Parties shall make payments
of all amounts required to be made pursuant to the foregoing  provisions of this
Article  IX to or for the  account of the Buyer  Indemnified  Party from time to
time  promptly  upon  receipt  of bills or  invoices  relating  thereto  or when
otherwise due and payable,  provided that the Buyer Indemnified Party has agreed
in writing to reimburse Seller and the other Control Parties for the full amount
of such payments if the Buyer Indemnified Party is ultimately  determined not to
be entitled to such indemnification; and

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this Article
IX and, in connection therewith,  shall furnish such records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                   ARTICLE X.

                               INDEMNIFICATION OF

                               THE CONTROL PARTIES

         Section 10.1  Indemnification  of Seller and the other Control Parties.
For a period of one year after the Closing  Date,  Buyer agrees to indemnify and
hold harmless Seller and the other Control Parties, and, where applicable, their
respective   partners,   officers,   directors,    employees,   and   affiliates
(collectively,  the "Seller  Indemnified  Parties") from and against any and all
Indemnified  Costs in  connection  with the  commencement  or  assertion  of any
third-party  action,  which any of the Seller  Indemnified  Parties may sustain,
arising out of, or with respect to, (i) any breach or default by Buyer of any of
the  representations,  warranties,  covenants  or  agreements  contained  in any
Transaction Document,  (ii) any obligations or liabilities to any finder, broker
or sales  agent  engaged or  retained  by Buyer or (iii) any act or  omission by
Buyer that  relates to the Assets and occurs after the  Closing.  Regardless  of
anything  contained in this Agreement to the contrary,  Buyer's  indemnification
liability  to each  Control  Party  shall  be  limited  to an  amount  equal  to
$24,000.00 for ROBERT BALL,  M.D.,  $1,728,000.00  for RLA and  $648,000.00  for
CAHS, and in no case shall the collective liability of the Buyer be greater than
the purchase price.

         Section 10.2 Defense of Third-Party  Claims. A Seller Indemnified Party
shall give prompt  written notice to Buyer of the  commencement  or assertion of
any third-party  action in respect of which such Seller  Indemnified Party shall
seek indemnification hereunder. Any failure so to notify Buyer shall not relieve
Buyer from any liability that it may have to such Seller Indemnified Party under
this Article X unless the failure to give such notice  materially  and adversely
prejudices  Buyer.  Buyer shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

          (a) The Seller  Indemnified  Party shall be entitled,  at his, her, or
     its own expense, to participate in the defense of such third-party action;

                  (b) Buyer  shall  obtain  the prior  written  approval  of the
Seller Indemnified  Party, which approval shall not be unreasonably  withheld or
delayed, before entering into or making any settlement,  compromise,  admission,
or acknowledgment of the validity of such third-party action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party or if; in the reasonable opinion of
the  Seller  Indemnified  Party,  such  settlement,  compromise,  admission,  or
acknowledgment  would have a material  adverse effect on its business or, in the
case of a Seller Indemnified Party who is a natural person, on his or her assets
or interests;

                  (c) Buyer  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the giving by each claimant or plaintiff to each Seller  Indemnified  Party of a
release from all liability in respect of such third-party action; and

                  (d) Buyer  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
(i) as to which Buyer fails to assume the defense within a reasonable  length of
time or (ii) to the extent the third-party action seeks an order, injunction, or
other  equitable  relief  against  the  Seller   Indemnified   Party  which,  if
successful, would materially adversely affect the business,  operations, assets,
or financial condition of the Seller Indemnified Party; provided,  however, that
the Seller Indemnified Party shall make no settlement, compromise, admission, or
acknowledgment  which would give rise to liability on the part of Buyer  without
the prior written consent of Buyer.

                  (e) Buyer shall make  payments  of all amounts  required to be
made  pursuant  to the  foregoing  provisions  of this  Article  X to or for the
account of the Seller  Indemnified Party from time to time promptly upon receipt
of bills  or  invoices  relating  thereto  or when  otherwise  due and  payable,
provided  that the Seller  Indemnified  Party has agreed in writing to reimburse
Buyer for the full amount of such  payments if the Seller  Indemnified  Party is
ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any third-party action pursuant to this Article X
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                   ARTICLE XI

                                     GENERAL

         Section 11.1 Costs.  Each party hereto  agrees to pay their  respective
costs and expenses incurred by them in the negotiation, preparation, performance
of and compliance  with all  agreements,  covenants and conditions  contained in
each Transaction Document to which it is a party, including, but not limited to,
their respective attorney's fees and accountant's fees.

         Section 11.2 No Brokers. Each party represents that no brokers,  agents
or finders are  involved in this  transaction  and each agrees to hold the other
harmless  from  liability  for  any  brokerage,  agency,  or  finder's  fees  or
commissions  with  respect  to  which  any  such  party  may  have  incurred  an
obligation.

         Section 11.3  Assignability.  This Agreement may not be assigned by any
party  hereto  without the prior  written  consent of all other  parties to this
Agreement,  except that Buyer may,  upon written  notice to Seller and the other
Control Parties, assign its rights pursuant to the non-competition covenants set
forth in Article  VIII hereof  without  the  written  consent of any other party
hereto,  provided that any such  assignment is made in connection with a sale or
transfer  of  (i)  all  or  substantially  all  of  the  Assets,   (ii)  all  or
substantially  all of the  business  or assets of Buyer  (including  the  assets
required to provide  Lithotripsy  Services to Reston Hospital Center),  (iii) at
least 50% of the  outstanding  voting stock of Buyer or consummation of a merger
or other  transaction  that  results in a change of control of Buyer,  or (iv) ^
Buyer's or Buyer's  affiliates' ^  obligations  under the  lithotripsy  services
agreement referred to in Section 7.5.

         Section 11.4 Entire Agreement. This Agreement and the other Transaction
Documents, together with all schedules and exhibits referred to herein, which by
this  reference  are hereby  incorporated  herein and made a part hereof for all
purposes,  contain the entire agreement  between the parties hereto with respect
to the  transactions  contemplated  herein,  and  supersede  all written or oral
negotiations,  commitments, warranties or representations, and cannot be altered
or otherwise  amended except pursuant to an instrument in writing signed by each
of the parties hereto. For all purposes of this Agreement, in lieu of physically
attaching referenced exhibits to this Agreement, such exhibits may be signed and
approved by the parties hereto and delivered concurrently with the execution and
delivery of this Agreement and deemed attached hereto.

         Section  11.5  Notices.  All  notices,   requests,  demands  and  other
communications  hereunder  shall be in writing  and shall be deemed to have been
duly given if personally  delivered or mailed by certified or  registered  mail,
postage prepaid to:

         If to Buyer:               Prime Lithotripsy Services, Inc.
                                    1301 Capital of Texas Highway
                                    Suite C-300
                                    Austin, TX 78746
                                    Attn: Cheryl L. Williams

                  With Copy to:     Akin, Gump, Strauss, Hauer & Feld L.L.P.
                                            816 Congress Avenue, Suite 1900
                                            Austin, TX 78701
                                            Attn: Tim LaFrey

         If to Seller:              Reston Hospital Lithotripter Joint Venture
                                    1850 Town Center Parkway
                                    Reston, Virginia  22090

                  With Copy to:     Michael P. Logan, Esquire
                                            Grad, Logan & Klewans, P.C.
                                            1421 Prince Street, Suite 320
                                            Alexandria, Virginia 22314

         If to RLA:                 Reston Lithotripsy Associates, Inc.
                                    1850 Town Center Parkway
                                    Reston, VA 22090
                                    Attn: A. Daniel Laurent, M.D.


                  With Copy to:     Michael P. Logan, Esquire
                                            Grad, Logan & Klewans, P.C.
                                            1421 Prince Street, Suite 320
                                            Alexandria, Virginia 22314

         If to CAHS:                Reston Hospital Center
                                    1850 Town Center Parkway
                                    Reston, VA 22090
                                    Attn: William A. Adams, CEO

                  With Copy to:     McGuire, Woods, Battle & Boothe LLP
                                            One James Center
                                            901 East Cary Street
                                            Richmond, Virginia 23219
                                            Attn: Thomas J. Stallings

         If to ROBERT BALL, M.D.: Robert Ball, M.D.
                                             7005 Symphony Court
                                             McLean, Virginia 22101

         Section 11.6  Waiver.  The failure of any party at any time or times to
require  performance of any provision hereof shall in no manner affect the right
at a later time to enforce the same.  Except as otherwise  provided  herein,  no
waiver by any party of any  condition,  or of any breach of any term,  covenant,
representation  or  warranty  contained  in this  Agreement,  in any one or more
instances,  shall be deemed to be or construed as a further or continuing waiver
of any such condition or breach, or a waiver of any other condition or breach of
any other term, covenant, representation or warranty.

         Section 11.7  Headings.  The headings of the sections and paragraphs of
this Agreement have been inserted for convenience of reference only and shall in
no way restrict or otherwise modify any of the terms or provisions hereof.

         Section 11.8 Materiality. The term "material" as used in this Agreement
is hereby defined to mean all accounting  adjustments,  costs, values,  damages,
deficiencies,  assessments  or expenses  with respect to the value of the Assets
and  businesses  to be purchased by Buyer  hereunder  or the  liabilities  to be
assumed by Buyer hereunder,  which either  separately or in the aggregate exceed
the sum of $10,000.

         Section 11.9 Counterparts.  This Agreement,  and each other Transaction
Document may be executed simultaneously in multiple counterparts,  each of which
when so executed shall be deemed to be an original,  and such counterparts shall
together constitute one and the same instrument.

         Section  11.10  Severance.  Should  any  portion of this  Agreement  be
declared  invalid and  unenforceable,  then such  portion  shall be deemed to be
severed from this Agreement and shall not affect the remainder thereof.

         Section 11.11 Extension of Benefits. All of the terms and conditions of
this  Agreement  shall be binding upon and inure to the benefit of, and shall be
enforceable  by,  the  parties  hereto  and  their  respective  heirs,  personal
representatives,  executors,  successors and assigns; provided, however, that in
the event that CAHS is dissolved, the terms and conditions of this Agreement, if
still applicable, shall solely be binding upon, and inure to the benefit of, HCA
Health Services of Virginia, Inc., a Virginia corporation and a member of CAHS.

         Section 11.12 Tax Advice. Each party hereto acknowledges that they have
consulted with their respective tax advisors in connection with the transactions
contemplated by this  Agreement,  and each party hereto  acknowledges  that they
have not relied  upon any  advice or  opinions  given by the other  party or its
attorneys or agents,  nor has any party hereto  guaranteed  any  particular  tax
consequences in connection with the transactions contemplated by this Agreement.

         Section 11.13  Survival of  Representations,  Warranties and Covenants.
All of the representations, warranties and covenants contained in this Agreement
shall survive the Closing Date for a period of two years.

         IN WITNESS WHEREOF, the parties have executed and delivered,  or caused
this Agreement to be executed and delivered by their  respective duly authorized
officers, on the day and year first above written.

BUYER:                     PRIME LITHOTRIPSY SERVICES, INC.


                                    By:/s/ Cheryl Williams
                                    ---------------------
                                    Printed Name: Cheryl Williams
                                    Title: Chief Financial Officer


SELLER:                    RESTON HOSPITAL LITHOTRIPTER
                                    JOINT VENTURE
                           Reston Lithotripsy Associates, Inc.
                           General Partner

                                    By: /s/ Michael R. Hardy, President
                                    ----------------------------------
                                    Printed Name: Michael R. Hardy, President
                                    Title: President, Reston Lithotripsy
                                           Associates, Inc.

RLA:                                RESTON LITHOTRIPSY ASSOCIATES, INC.


                                    By: /s/ Michael R. Hardy
                                    ------------------------
                                    Printed Name: Michael R. Hardy
                                    Title: President

CAHS:                      COLUMBIA ARLINGTON HEALTHCARE SYSTEM, L.L.C.


                                    By:/s/ William A. Adams
                                    -----------------------
                                    Printed Name: William A. Adams
                                    Title: COO/Authorized Agent

BALL:

                                    /s/ Robert Ball, M.D.
                                    -------------------------------------
                                    ROBERT BALL, M.D.



<PAGE>


                                 Schedule II(e)

                        Non-Assignable Permits of Seller

Business and Professional Occupations License issued by the County of
Fairfax, Virginia.


<PAGE>



                                 Schedule II(f)

                               List of Procedures

                           Year                          Procedures

                           1996                               506

                           1997                               443

                           1998                               534

                           1999, up to May 31, 1999           228








                                Maryland Patients

                           Year                             Patients

                           1998                                 8

                           1999, up to June 29, 1999            7


<PAGE>



                                                                  Schedule II(m)

                                Ownership of RLA

  Amer Z. Al-Juberi, M.D.
  Janice Arnold, M.D.
  John J. Basile, M.D.
  Michael E. Beall, M.D.
  Myron Berger, M.D.
  Robert M. Berger, M.D.
  Mark Bilowus, M.D.
  Giovanni DiSandro, M.D.
  William Glover, Jr., M.D.
  Michael R. Hardy, M.D.
  A. Daniel Laurent, M.D.
  J. Martin Lebowitz, M.D.
  EK Seng Lou, M.D.
  Jeff Pan, M.D.
  Philip A. St. Raymond, M.D.
  William Reha, M.D.
  Domingo Suatengco, M.D.
  Anthony Vara, M.D.


<PAGE>


                                   Schedule V

                          Allocation of Purchase Price


                                     <PAGE>



                                    EXHIBIT A

                  Form of Assignment and Warranty Bill of Sale


<PAGE>



                                    EXHIBIT B

                          Form of Non-compete Agreement


                            Non-competition Agreement

         THIS NON-COMPETITION AGREEMENT (this "Agreement") entered into this ___
day of July, 1999 (the  "Effective  Date"),  by the undersigned  individual (the
"Restricted Party") for the benefit of Prime Medical Services,  Inc., a Delaware
corporation (the "Company") and the Company's affiliates.

         WHEREAS,  the  Company,  through a  subsidiary,  has  acquired  certain
lithotripsy  equipment from the Restricted  Party and certain  affiliates of the
Restricted Party; and

         WHEREAS,  as a material  inducement for the Company's  purchase of such
equipment, the Restricted Party has agreed, among other things, not to engage in
certain competitive  activities,  or assist or participate with any other person
or entity engaging in such activities, as provided herein.

         NOW, THEREFORE,  for good and valuable  consideration,  the receipt and
sufficiency of which are hereby acknowledged and confessed, the Restricted Party
hereby covenants and agrees as follows:

         1. Agreement.  The Restricted  Party hereby  covenants and agrees that,
until  the  expiration  of  the  Restriction  Period  (as  defined  below),  the
Restricted  Party will not,  directly or indirectly,  either through any kind of
ownership  (other than ownership of securities of a publicly held corporation of
which the  Restricted  Party  owns less than five  percent  (5%) of any class of
outstanding  securities),   or  as  a  principal,   agent,  employer,   advisor,
consultant, co-partner or in any individual or representative capacity whatever,
either for the  Restricted  Party's  own benefit or for the benefit of any other
person,  corporation or other entity,  without the prior written  consent of the
Company,  commit any of the following  acts  described in paragraphs (a) through
(c) below,  which acts shall be  considered  violations  of this covenant not to
compete:

         (a) Lithotripsy Services. Except as permitted pursuant to paragraph (d)
below,  directly or indirectly provide lithotripsy  services,  including without
limitation,  patient  lithotripsy  services,  lithotripsy  management  services,
lithotripter  leasing,  or similar lithotripsy  services,  anywhere within fifty
(50) miles of Columbia  Reston  Hospital  Center in Reston,  Virginia.  The area
described  in  the  preceding  sentence  is  hereinafter   referred  to  as  the
"Restricted Area."

         (b) Interference  with Business  Relationships.  Directly or indirectly
request or advise any patient or physician or any other person,  corporation  or
other  entity  having a  business  relationship  with the  Company or any of the
Company's  affiliates  to withdraw,  curtail,  or cancel its business  with such
entity.

         (c) Solicitation of Employees. Directly or indirectly hire any employee
of the  Company  or any of the  Company's  affiliates  or induce or  attempt  to
influence  any  employee of the Company or any of the  Company's  affiliates  to
terminate his or her employment with such entity.

         (d) Medical  Judgment.  Nothing in this Agreement shall be construed to
limit or infringe upon the professional  medical judgment or ability to practice
medicine  of the  Restricted  Party,  if the  Restricted  Party  is a  physician
(including,  but not limited to, the  selection of  appropriate  facilities  for
medical  care),  and  no  exercise  of  professional  medical  judgment  or  act
constituting  the practice of medicine  shall be  considered a violation of this
Agreement.

        2. Restriction Period. For purposes of this Agreement,  the "Restriction
Period" shall begin on the  Effective  Date and continue  until five (5) years
after the Effective Date.

        3. General. For purposes of this Agreement,  the Company's affiliates
shall  include  its  current  and future  (throughout  the  Restriction  Period)
subsidiaries  and  affiliates.  The Restricted  Party has reviewed and carefully
considered the provisions of this Agreement and, having done so, agrees that the
restrictions  set forth herein (a) are fair and reasonable with respect to time,
geographic area and scope, (b) are not unduly burdensome, and (c) are reasonably
required for the protection of the  legitimate  interests of the Company and its
affiliates.  The  Restricted  Party  agrees that a violation  on its part of any
covenant  contained in this  Agreement will cause the Company and its affiliates
irreparable  damage for which remedies at law may be insufficient,  and for that
reason, agrees that the Company and its affiliates shall each,  independently be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at  law or in  equity,  may be  available,  including,  specifically,
recovery of additional damages.

         4.       Miscellaneous.
         (a)  Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written, relating to these
transactions  and  constitutes the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by the Company.

         (b)      Expenses.  The Restricted  Party shall pay all costs and
expenses incurred by it in connection  with this Agreement, including the fees
and disbursements of its counsel.
         (c) Invalid  Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision  shall be fully  severable,  this  Agreement  shall be  construed  and
enforced as if such  illegal,  invalid,  or  unenforceable  provision  had never
comprised  a part  of  this  Agreement,  and the  remaining  provisions  of this
Agreement shall remain in full force and effect and shall not be affected by the
illegal,  invalid,  or  unenforceable  provision or by its  severance  from this
Agreement.

         (d)  Waiver.  No  failure  or  delay  on the  part  of the  Company  in
exercising  any  right,  power,  or  privilege  hereunder  or  under  any of the
documents  delivered in connection with this Agreement shall operate as a waiver
of such right, power, or privilege;  nor shall any single or partial exercise of
any such  right,  power,  or  privilege  preclude  any other or future  exercise
thereof or the exercise of any other right, power or privilege.

         (e)  Construction.  This  Agreement  and any  documents or  instruments
delivered  pursuant hereto or in connection  herewith shall be construed without
regard to the identity of the person who drafted the various  provisions  of the
same.  Each and every  provision of this Agreement and such other  documents and
instruments shall be construed as though all of the parties participated equally
in the drafting of the same. Consequently, the Restricted Party acknowledges and
agrees that any rule of construction  that a document is to be construed against
the  drafting  party shall not be  applicable  either to this  Agreement or such
other documents and instruments.

         (f)  Forum.   The   Restricted   Party  consents  to  the  in  personam
jurisdiction  of any state or federal court in  Alexandria,  Virginia and waives
any objection to the venue of any such suit, action or proceeding.  In the event
that the Restricted Party institutes a proceeding  involving this Agreement in a
jurisdiction outside Alexandria,  Virginia, the Restricted Party shall indemnify
the Company and its  affiliates for any losses and expenses that may result from
the failure to institute  such  proceeding  only in a state or federal  court in
Alexandria,  Virginia,  including  without  limitation any  additional  expenses
incurred as a result of litigating in another  jurisdiction,  such as reasonable
fees and expenses of local counsel and travel and lodging  expenses for parties,
witnesses, experts and support personnel.

                            [Signature page follows]


<PAGE>

                                 SIGNATURE PAGE

                                       TO

                            NON-COMPETITION AGREEMENT

         IN  WITNESS  WHEREOF,  the  Restricted  Party  has duly  executed  this
Agreement as of the day and year first above written.

                                RESTRICTED PARTY

                                   Signature:

                                  Printed Name:



<PAGE>



                                    EXHIBIT C

                          Form of Non-compete Agreement

                            Non-competition Agreement

         THIS NON-COMPETITION AGREEMENT (this "Agreement") entered into this ___
day of July, 1999 (the  "Effective  Date"),  by the undersigned  individual (the
"Restricted Party") for the benefit of Prime Medical Services,  Inc., a Delaware
corporation (the "Company") and the Company's affiliates.

         WHEREAS,  the  Company,  through a  subsidiary,  has  acquired  certain
lithotripsy  equipment from the Restricted  Party and certain  affiliates of the
Restricted Party; and

         WHEREAS,  as a material  inducement for the Company's  purchase of such
equipment, the Restricted Party has agreed, among other things, not to engage in
certain competitive  activities,  or assist or participate with any other person
or entity engaging in such activities, as provided herein.

         NOW, THEREFORE,  for good and valuable  consideration,  the receipt and
sufficiency of which are hereby acknowledged and confessed, the Restricted Party
hereby covenants and agrees as follows:

         1. Agreement.  The Restricted  Party hereby  covenants and agrees that,
until  the  expiration  of  the  Restriction  Period  (as  defined  below),  the
Restricted  Party will not,  directly or indirectly,  either through any kind of
ownership  (other than ownership of securities of a publicly held corporation of
which the  Restricted  Party  owns less than five  percent  (5%) of any class of
outstanding  securities),   or  as  a  principal,   agent,  employer,   advisor,
consultant, co-partner or in any individual or representative capacity whatever,
either for the  Restricted  Party's  own benefit or for the benefit of any other
person,  corporation or other entity,  without the prior written  consent of the
Company,  commit any of the following  acts  described in paragraphs (a) through
(c) below,  which acts shall be  considered  violations  of this covenant not to
compete:

         (a) Lithotripsy Services. Except as permitted pursuant to paragraph (d)
below,  directly or indirectly provide lithotripsy  services,  including without
limitation,  patient  lithotripsy  services,  lithotripsy  management  services,
lithotripter  leasing,  or similar lithotripsy  services,  anywhere within fifty
(50) miles of Columbia  Reston  Hospital  Center in Reston,  Virginia.  The area
described  in  the  preceding  sentence  is  hereinafter   referred  to  as  the
"Restricted Area." Notwithstanding the foregoing, the passive ownership interest
by  Restricted  Party  in that  certain  lithotripsy  partnership  described  on
Exhibit-A  hereto  shall not be deemed a violation by  Restricted  Party of this
paragraph (a); provided,  however, that Restricted Party agrees that, during the
term of this  Agreement,  Restricted  Party shall not increase its  ownership in
such lithotripsy partnership.

         (b) Interference  with Business  Relationships.  Directly or indirectly
request or advise any patient or physician or any other person,  corporation  or
other  entity  having a  business  relationship  with the  Company or any of the
Company's  affiliates  to withdraw,  curtail,  or cancel its business  with such
entity.

         (c) Solicitation of Employees. Directly or indirectly hire any employee
of the  Company  or any of the  Company's  affiliates  or induce or  attempt  to
influence  any  employee of the Company or any of the  Company's  affiliates  to
terminate his or her employment with such entity.

         (d) Medical  Judgment.  Nothing in this Agreement shall be construed to
limit or infringe upon the professional  medical judgment or ability to practice
medicine  of the  Restricted  Party,  if the  Restricted  Party  is a  physician
(including,  but not limited to, the  selection of  appropriate  facilities  for
medical  care),  and  no  exercise  of  professional  medical  judgment  or  act
constituting  the practice of medicine  shall be  considered a violation of this
Agreement.

         2.       Restriction  Period. For purposes of this Agreement,  the
"Restriction  Period" shall begin on the Effective Date and continue until five
(5) years after the Effective Date.
         3.       General.  For purposes of this Agreement,  the Company's
affiliates  shall  include its current and future  (throughout  the  Restriction
Period)  subsidiaries  and  affiliates.The  Restricted  Party has  reviewed  and
carefully  considered  the  provisions of this  Agreement  and,  having done so,
agrees that the  restrictions  set forth herein (a) are fair and reasonable with
respect to time,  geographic area and scope, (b) are not unduly burdensome,  and
(c) are reasonably  required for the  protection of the legitimate  interests of
the Company and its affiliates.
         The  Restricted  Party  agrees  that a  violation  on its  part  of any
covenant  contained in this  Agreement will cause the Company and its affiliates
irreparable  damage for which remedies at law may be insufficient,  and for that
reason, agrees that the Company and its affiliates shall each,  independently be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at  law or in  equity,  may be  available,  including,  specifically,
recovery of additional damages.

         4.       Miscellaneous.
         (a)  Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written, relating to these
transactions  and  constitutes the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by the Company.

         (b) Expenses.  The Restricted  Party shall pay all costs and expenses
incurred by it in connection with this  Agreement,  including the fees and
disbursements of its counsel.

         (c)Invalid  Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision  shall be fully  severable,  this  Agreement  shall be  construed  and
enforced as if such  illegal,  invalid,  or  unenforceable  provision  had never
comprised  a part  of  this  Agreement,  and the  remaining  provisions  of this
Agreement shall remain in full force and effect and shall not be affected by the
illegal,  invalid,  or  unenforceable  provision or by its  severance  from this
Agreement.

         (d)  Waiver.  No  failure  or  delay  on the  part  of the  Company  in
exercising  any  right,  power,  or  privilege  hereunder  or  under  any of the
documents  delivered in connection with this Agreement shall operate as a waiver
of such right, power, or privilege;  nor shall any single or partial exercise of
any such  right,  power,  or  privilege  preclude  any other or future  exercise
thereof or the exercise of any other right, power or privilege.

         (e)  Construction.  This  Agreement  and any  documents or  instruments
delivered  pursuant hereto or in connection  herewith shall be construed without
regard to the identity of the person who drafted the various  provisions  of the
same.  Each and every  provision of this Agreement and such other  documents and
instruments shall be construed as though all of the parties participated equally
in the drafting of the same. Consequently, the Restricted Party acknowledges and
agrees that any rule of construction  that a document is to be construed against
the  drafting  party shall not be  applicable  either to this  Agreement or such
other documents and instruments.

         (f)  Forum.   The   Restricted   Party  consents  to  the  in  personam
jurisdiction  of any state or federal court in  Alexandria,  Virginia and waives
any objection to the venue of any such suit, action or proceeding.  In the event
that the Restricted Party institutes a proceeding  involving this Agreement in a
jurisdiction outside Alexandria,  Virginia, the Restricted Party shall indemnify
the Company and its  affiliates for any losses and expenses that may result from
the failure to institute  such  proceeding  only in a state or federal  court in
Alexandria,  Virginia,  including  without  limitation any  additional  expenses
incurred as a result of litigating in another  jurisdiction,  such as reasonable
fees and expenses of local counsel and travel and lodging  expenses for parties,
witnesses, experts and support personnel.

                            [Signature page follows]


<PAGE>

                                 SIGNATURE PAGE

                                       TO

                            NON-COMPETITION AGREEMENT

         IN  WITNESS  WHEREOF,  the  Restricted  Party  has duly  executed  this
Agreement as of the day and year first above written.

                                RESTRICTED PARTY

                                   Signature:

                                  Printed Name:


<PAGE>


                                    EXHIBIT A

                          TO NON-COMPETITION AGREEMENT

                       DESCRIPTION OF EXISTING INVESTMENT

<PAGE>

                        AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                           MOBILE KIDNEY STONE CENTERS
                             OF CALIFORNIA III, L.P.


<PAGE>



                                    AGREEMENT

                             OF LIMITED PARTNERSHIP

                                       OF

               MOBILE KIDNEY STONE CENTERS OF CALIFORNIA III, L.P.
               ---------------------------------------------------


                                TABLE OF CONTENTS


         1.       FORMATION..................................................1
                  ---------

         2.       NAME.......................................................1
                  ----

         3.       OFFICES....................................................1
                  -------

         4.       PURPOSE....................................................2
                  -------

         5.       TERM.......................................................2
                  ----

         6.       CERTAIN DEFINED TERMS......................................2
                  ---------------------

         7.       CAPITAL CONTRIBUTIONS AND DILUTION OFFERINGS...............6
                  --------------------------------------------

         8.       GUARANTIES.................................................7
                  ----------

         9.       CONDITIONS TO THE CAPITAL CONTRIBUTIONS OF CERTAIN LIMITED
                  ----------------------------------------------------------
                  PARTNERS...................................................7
                  --------

         10.      REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE GENERAL
                  --------------------------------------------------------
                  PARTNER....................................................7
                  -------

         11.      ADMISSION OF LIMITED PARTNERS..............................8
                  -----------------------------

         12.      CAPITAL ACCOUNTS...........................................9
                  ----------------

         13.      ALLOCATIONS...............................................10
                  -----------

         14.      DISTRIBUTIONS.............................................13
                  -------------

         l5.      RIGHTS AND OBLIGATIONS OF LIMITED PARTNERS................14
                  ------------------------------------------

         16.      LIMITED LIABILITY.........................................16
                  -----------------


                                                         i


<PAGE>




         17.      TRANSFER OF INTERESTS AND ADMISSION OF PARTNERS...........16
                  -----------------------------------------------

         18.      OPTIONAL PURCHASE OF LIMITED PARTNERSHIP INTERESTS ON
                  -----------------------------------------------------
                  CERTAIN EVENTS............................................20
                  --------------

         19.      SALE, ASSIGNMENT OR OTHER TRANSFER OF THE GENERAL PARTNER'S
                  -----------------------------------------------------------
                  INTEREST..................................................26
                  --------

         20.      TERMINATION OF THE SERVICES OF THE GENERAL PARTNER........27
                  --------------------------------------------------

         21.      MANAGEMENT AND OPERATION OF BUSINESS......................27
                  ------------------------------------

         22.      RESERVES..................................................30
                  --------

         23.      INDEMNIFICATION AND EXCULPATION OF THE GENERAL PARTNER
                  ------------------------------------------------------
                   .........................................................30

         24.      DISSOLUTION OF THE PARTNERSHIP............................31
                  ------------------------------

         25.      DISTRIBUTION UPON DISSOLUTION.............................32
                  -----------------------------

         26.      BOOKS OF ACCOUNT, RECORDS AND REPORTS.....................33
                  -------------------------------------

         27.      NOTICES...................................................34
                  -------

         28.      AMENDMENTS................................................34
                  ----------

         29.      LIMITATIONS ON AMENDMENTS.................................34
                  -------------------------

         30.      MEETINGS, CONSENTS AND VOTING.............................35
                  -----------------------------

         31.      SUBMISSIONS TO THE LIMITED PARTNERS.......................35
                  -----------------------------------

         32.      ADDITIONAL DOCUMENTS......................................35
                  --------------------

         33.      SURVIVAL OF RIGHTS........................................36
                  ------------------

         34.      INTERPRETATION AND GOVERNING LAW..........................36
                  --------------------------------

         35.      SEVERABILITY..............................................36
                  ------------

         36.      AGREEMENT IN COUNTERPARTS.................................36
                  -------------------------


                                                        ii


<PAGE>




         37.      THIRD PARTIES.............................................36
                  -------------

         38.      POWER OF ATTORNEY.........................................36
                  -----------------

         39.      ARBITRATION...............................................37
                  -----------

         40.      CREDITORS.................................................37
                  ---------


                                    SCHEDULES

Schedule A  -  Schedule of Partnership Interests


                                                        iii


<PAGE>



THE  LIMITED  PARTNERSHIP  INTERESTS  REPRESENTED  BY THIS  LIMITED  PARTNERSHIP
AGREEMENT HAVE NOT BEEN REGISTERED  WITH THE SECURITIES AND EXCHANGE  COMMISSION
UNDER THE  SECURITIES ACT OF 1933, AS AMENDED,  UNDER THE  CALIFORNIA  CORPORATE
SECURITIES LAW OF 1968, AS AMENDED,  OR REGISTERED UNDER SIMILAR LAWS OR ACTS OF
OTHER  STATES IN RELIANCE  UPON  EXEMPTIONS  UNDER SUCH LAWS.  IN  ADDITION,  NO
TRANSFERS OF LIMITED  PARTNERSHIP  INTERESTS MAY BE MADE WITHOUT COMPLIANCE WITH
THE RESTRICTIONS SET FORTH IN ARTICLE 17 BELOW.

                                    AGREEMENT

                             OF LIMITED PARTNERSHIP

                                       OF

                           MOBILE KIDNEY STONE CENTERS
                             OF CALIFORNIA III, L.P.

                  THIS AGREEMENT OF LIMITED  PARTNERSHIP  (the  "Agreement")  is
made as of August  12,  1999,  by and  among  MOBILE  KIDNEY  STONE  CENTERS  OF
CALIFORNIA,  LTD. I, a California limited  partnership (the "General  Partner"),
and persons listed on Schedule A attached hereto as the Limited Partners.

                  1.       FORMATION.
                           ---------

                  The  Partnership  was  formed  pursuant  to the  filing in the
Office of the Secretary of State of California on or about February 2, 1999 of a
Certificate of Limited Partnership in accordance with the provisions of the Act.

                  2.       NAME.
                           ----

                    2.1 The name of the  Partnership  is  "Mobile  Kidney  Stone
               Centers of California III, L.P."

                  2.2 The  Partnership  business  shall be conducted  under such
names as the General  Partner may from time to time deem necessary or advisable,
provided that appropriate amendments to this Agreement and all necessary filings
under  applicable  assumed  or  fictitious  name  statutes  or the Act are first
obtained.

                  3.       OFFICES.
                           -------

                  3.1 The initial  principal office of the Partnership  shall be
at 1301 Capital of Texas Highway,  Suite C-300,  Austin, Texas 78746, or at such
other place as the General  Partner may from time to time designate by notice to
the Limited Partners. Pursuant to the Act, the Partnership will


                                                        -1-


<PAGE>



also maintain certain  Partnership records in California at a location set forth
in the Partnership's Certificate of Limited Partnership (the "Records Office").

                  3.2 The Partnership  may have such  additional  offices as the
General Partner may, from time to time, deem necessary or advisable.

                  4.       PURPOSE.
                           -------

                  The purpose and business of the  Partnership  shall be: (i) to
acquire and operate one or more transportable  lithotripters (or any other renal
stone  treatment  equipment)  for the  treatment  of renal  stones  primarily in
California in the counties of Alameda, Contra Costa, Merced, Nevada, Placer, San
Joaquin and Stanislaus,  or in such other location(s) as the General Partner may
determine,  in  its  sole  discretion,  to be  in  the  best  interests  of  the
Partnership;  (ii) to acquire  and  operate  in the future any other  urological
device or equipment; provided, that such equipment as of the date of acquisition
by the  Partnership  has received FDA  premarket  approval;  (iii) to acquire an
interest  in any  business  entity,  including,  without  limitation,  a limited
partnership,  limited  liability  company or  corporation,  that  engages in any
business activity described in this Article 4; and (iv) to engage in any and all
activities incidental or related to the foregoing, upon and subject to the terms
and conditions of this Agreement.

                  5.       TERM.
                           ----

                  The Partnership  shall terminate on December 31, 2049,  unless
sooner terminated as herein provided.

                  6.       CERTAIN DEFINED TERMS.
                           ---------------------

                  Certain terms used in this Agreement  shall have the following
meanings:

                    Act.   The  Act  means  the   California   Revised   Limited
               Partnership Act, as then in effect.

                    Affiliate.  An  Affiliate  is (i) any  person,  partnership,
               corporation,   association  or  other  legal  entity   ("person")
               directly or indirectly controlling, controlled by or under common
               control  with  another   person;   (ii)  any  person   owning  or
               controlling  10% or more of the  outstanding  voting  interest of
               such other person; (iii) any officer, director or partner of such
               person; and (iv) if such other person is an officer,  director or
               partner, any entity for which such person acts in such capacity.

                    Agreement.  This  Agreement of Limited  Partnership,  as the
               same may be amended from time to time.

                    Bank.  First-Citizens  Bank & Trust Company,  its successors
               and assigns.



                                                        -2-


<PAGE>



                    Capital  Account.  The  Partnership  capital  account  of  a
               Partner as computed pursuant to Article 12 of this Agreement.

                  Capital  Contributions.  All capital  contributions  made by a
Partner or his or her  predecessor  in  interest  which shall  include,  without
limitation, contributions made pursuant to Article 7 of this Agreement.

     Capital  Transaction.  Any transaction which, were it to generate proceeds,
would produce Partnership Sales Proceeds or Partnership Refinancing Proceeds.

                    Code.  The  Internal  Revenue Code of 1986,  as amended,  or
               corresponding provisions of subsequent, superseding revenue laws.

                  Dilution  Offering.   As  provided  in  Article  7.4  of  this
Agreement,  the future offering of additional limited  partnership  interests in
the  Partnership  as  determined  by the General  Partner.  Except as  otherwise
provided in Article 7.4, any successful  Dilution Offering will  proportionately
reduce the Percentage Interests of the then current Partners in the Partnership.

                    Domestic Proceeding. Any divorce,  annulment,  separation or
               similar domestic proceeding between a married couple.

                  Equipment.   The  equipment  used  in  the  operation  of  the
Lithotripsy System, including the mobile transport vehicle, the lithotripter and
miscellaneous  medical  equipment  and  supplies,  and  any  similar  additional
equipment acquired by the Partnership in the future.

                  FDA.  The United States Food and Drug Administration.


                    General  Partner.  The general  partner of the  Partnership,
               Mobile Kidney Stone Centers of  California,  Ltd. I, a California
               limited partnership.

                  Guaranty.  The  Guaranty  Agreement  pursuant  to  which  each
Limited Partner will guarantee a portion of the Partnership's obligations to the
Bank under the Loan.  The form of the  Guaranty  Agreement  is  included  in the
Subscription Packet accompanying the Memorandum.

                  Initial Limited Partner.  Stan Johnson,  a resident of Arizona
and an  Affiliate  of the general  partner of the General  Partner.  The Initial
Limited Partner is to be the only limited partner of the Partnership  until such
time as the new Limited Partners are admitted to the Partnership,  at which time
the Initial Limited Partner shall withdraw from the Partnership.

                  Limited Partners.  The Limited Partners are those investors in
the Units  admitted  to the  Partnership  and any person  admitted  as a Limited
Partner in accordance with the provisions of this Agreement.


                                                        -3-


<PAGE>



                    Lithotripter.  The extracorporeal shock-wave lithotripter to
               be acquired by the Partnership and any  replacements  therefor or
               additional lithotripters to be purchased by the Partnership.

                    Lithotripsy   System.   The  mobile  transport  vehicle  and
               operational Lithotripter.

                  Loan.  The  loan  of up to  $487,125  from  the  Bank  to  the
Partnership.  Loan  proceeds will be used by the  Partnership  to (i) acquire an
extracorporeal shockwave lithotripter with options (estimated at $400,000), (ii)
acquire  and upfit a mobile van to  transport  the  lithotripter  (estimated  at
$50,000)  and (iii) pay state  sales taxes on the  purchase  of the  Lithotripsy
System (estimated at $37,125).

                    Losses.  The net loss  (including  Net Losses  from  Capital
               Transactions) of the Partnership for each Year of the Partnership
               as determined for federal income tax purposes.

                  Majority  in Interest  of the  Limited  Partners.  The Limited
Partners who hold more than 50% of the Percentage  Interests in the  Partnership
held by the Limited Partners.

                    Memorandum. The Confidential Private Placement Memorandum of
               the  Partnership  dated  February  8,  1999,  as  amended  or  as
               supplemented.

                  Net Gains from Capital Transactions. The gains realized by the
Partnership  as a result of or upon any sale,  exchange,  condemnation  or other
disposition of the capital assets of the Partnership (which assets shall include
Code Section 1231 assets) or as a result of or upon the damage or destruction of
such capital assets.

                  Net Losses from Capital  Transactions.  The losses realized by
the Partnership as a result of or upon any sale, exchange, condemnation or other
disposition of the capital assets of the  Partnership  (which shall include Code
Section 1231 assets) or as a result of or upon the damage or destruction of such
capital assets.

                    Offering.  The  offer  to  potential  investors  of 60 Units
               pursuant to the Memorandum.

                    Partners.  The General  Partner  and the  Limited  Partners,
               collectively,  where no distinction is required by the context in
               which the term is used herein.

                    Partnership.  Mobile Kidney Stone Centers of California III,
               L.P., a California limited partnership.

                  Partnership Cash Flow. For the applicable  period, the excess,
if any,  of (A) the sum of (i) all  gross  receipts  from  any  source  for such
period,  other than from  Partnership  loans,  Capital  Transactions and Capital
Contributions,  and (ii) any funds released by the  Partnership  from previously
established  reserves,  over  (B) the sum of (i) all cash  expenses  paid by the
Partnership for


                                                        -4-


<PAGE>



such  period;  (ii) the  amount of all  payments  of  principal  on loans to the
Partnership;  (iii)  capital  expenditures  of the  Partnership;  and (iv)  such
reasonable  reserves as the General  Partner shall deem  necessary or prudent to
set  aside  for  future  repairs,   improvements  or  equipment  replacement  or
additions,  or to meet working  capital  requirements  or foreseen or unforeseen
future liabilities and contingencies of the Partnership; provided, however, that
the  amounts  referred  to in (B)(i),  (ii) and (iii)  above shall be taken into
account  only to the extent not funded by Capital  Contributions,  loans or paid
out of previously  established reserves.  Such term shall also include all other
funds deemed  available for  distribution  and designated as  "Partnership  Cash
Flow" by the General Partner.

                    Partnership  Interest.  The  interest  of a  Partner  in the
               Partnership as defined by the Act and this Agreement.

                  Partnership  Refinancing Proceeds.  The cash realized from the
refinancing of Partnership assets after retirement of any secured loans and less
(i) payment of all expenses  relating to the transaction and (ii)  establishment
of such  reasonable  reserves as the General  Partner  shall deem  necessary  or
prudent to set aside for future repairs,  improvements, or equipment replacement
or additions,  or to meet working capital requirements or foreseen or unforeseen
future liabilities or contingencies of the Partnership.

                  Partnership  Sales Proceeds.  The cash realized from the sale,
exchange,  casualty  or other  disposition  of all or a portion  of  Partnership
assets after the retirement of all secured loans and less (i) the payment of all
expenses  related to the transaction and (ii)  establishment  of such reasonable
reserves as the General Partner shall deem necessary or prudent to set aside for
future repairs,  improvements, or equipment replacement or additions, or to meet
working  capital  requirements or foreseen or unforeseen  future  liabilities or
contingencies of the Partnership.

                  Percentage  Interest.  The  interest  of each  Partner  in the
Partnership,  to be  determined  initially  in the case of a Limited  Partner by
reference to his or her Unit ownership based upon the Limited  Partners  holding
an aggregate 60% Percentage Interest in the Partnership,  with each initial Unit
sold representing an initial 1% interest. The General Partner will initially own
a 40% Percentage  Interest in the Partnership.  A Partner's  Percentage Interest
may be reduced by a future Dilution Offering. The Partners' Percentage Interests
in the Partnership as of the date hereof are as set forth in Schedule A attached
hereto. Any future  adjustments in the Partners'  Percentage  Interests,  due to
future Dilution Offerings or otherwise,  will also be reflected by amendments to
Schedule A.

                    Profit.  The net income of the  Partnership  (including  Net
               Gains from Capital Transactions) for each Year of the Partnership
               as determined for federal income tax purposes.

                  Pro  Rata  Basis.   In   connection   with  an  allocation  or
distribution,  an allocation  or  distribution  in proportion to the  respective
Percentage Interests of the class of Partners to which reference is made.


                                                        -5-


<PAGE>



                    Sales Agency  Agreement.  The sales agency agreement through
               which  MedTech  Investments,  Inc.,  an  Affiliate of the General
               Partner  and  a   broker-dealer   company   registered  with  the
               Securities  and Exchange  commission and a member of the National
               Association of Securities Dealers,  Inc. shall offer and sell the
               limited partnership  interest of the Partnership  pursuant to the
               Memorandum.

                    Sales Commission.  The $250 sales commission paid to MedTech
               Investments, Inc. for each Unit sold.

                  Service.  The Internal Revenue Service.


                  Units.   The  60  equal  limited  partner   interests  in  the
Partnership offered pursuant to the Memorandum for a price per Unit of $2,500 in
cash, plus a personal guaranty of 1% of the Partnership's  obligations under the
Loan (up to $4,871.25 principal guaranty obligation).

                    Year. An annual  accounting  period ending on December 31 of
               each year during the term of the Partnership.

                  7.       CAPITAL CONTRIBUTIONS AND DILUTION OFFERINGS.
                           --------------------------------------------

                  7.1  General  Partner  Contribution.  On or before the date of
this  Agreement,  the  General  Partner  will  contribute  to the capital of the
Partnership  cash in the amount  equal to 40% (up to $100,000) of the total cash
contributed to the  Partnership by the Partners in the Offering made pursuant to
the Memorandum.

                  7.2 Limited Partner Contribution.  Each Limited Partner hereby
agrees to contribute and shall  contribute to the capital of the  Partnership on
the date of his or her  admission to the  Partnership  the cash amount set forth
opposite his or her name on Schedule A attached hereto.

                    7.3 No Interest.  Except as otherwise  provided  herein,  no
               interest shall be paid on any  contribution to the capital of the
               Partnership.

                  7.4 Dilution  Offerings.  If the General Partner,  in its sole
discretion,  determines that it is in the best interest of the Partnership,  the
General Partner may, from time to time, offer, sell and issue, for and on behalf
of the Partnership,  additional limited partnership interests in the Partnership
(a  "Dilution  Offering")  to  investors  who are not already  Limited  Partners
("Qualified  Investors").  The primary purpose of any Dilution Offering would be
to raise additional capital for any legitimate  Partnership purpose as set forth
in Article 4. Any limited partnership  interests offered by the Partnership in a
Dilution  Offering  shall  be sold in the  manner  and  according  to the  terms
prescribed in the sole  discretion of the General  Partner;  provided,  however,
that any additional limited partnership interests offered in a Dilution Offering
will be sold for a price no lower than the highest price for which proportionate
limited  partnership  interests in the Partnership  have been previously sold by
the Partnership unless otherwise determined by a vote of the General Partner and


                                                        -6-


<PAGE>



a Majority in Interest of the Limited Partners.  Any sale of additional  limited
partnership  interests  will  result  in  the  proportionate   dilution  of  the
Percentage Interests of the existing Partners. Notwithstanding the above, in the
event of a  Dilution  Offering,  the  General  Partner  may  elect,  in its sole
discretion,   to  prevent   dilution  of  its  Percentage   Interest  by  either
contributing  additional  capital to the  Partnership  or purchasing  additional
limited partnership  interests in any Dilution Offering.  Limited Partners shall
have no right to purchase  additional  limited partner interests in any Dilution
Offering or to make additional capital contributions or take any other action to
prevent dilution of their Percentage Interest.  Any investor acquiring a limited
partnership interest in a Dilution Offering shall agree to be bound by the terms
of this Agreement,  and shall be automatically  admitted as a Limited Partner of
the Partnership.  Any adjustment in the Partners' Percentage Interests resulting
from a  Dilution  Offering  shall be set forth on an  amended  Schedule  A to be
attached hereto.

                  8.       GUARANTIES.
                           ----------

                  Each Partner agrees to execute and deliver to the  Partnership
on the date of his or her admission to the  Partnership a Guaranty in the amount
set forth opposite his or her name on Schedule A attached hereto.

                  9.       CONDITIONS TO THE CAPITAL CONTRIBUTIONS OF CERTAIN
                           --------------------------------------------------
                           LIMITED PARTNERS.
                           ----------------

                  The  obligations  of  any  Limited  Partners  acquiring  their
Partnership  Interests  in the  Offering  or a  Dilution  Offering  to make cash
Capital   Contributions   hereunder  are  subject  to  the  condition  that  the
representations, warranties, agreements and covenants of the General Partner set
forth in Article 10 of this  Agreement are and shall be true and correct or have
been and will have been complied with in all material  respects on the date such
Capital  Contributions  are  required to be made,  except to the extent that any
such representation or warranty expressly pertains to an earlier date.

                  10.      REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE
                           ------------------------------------------------
                           GENERAL PARTNER.
                           ---------------

                    10.1 The General  Partner hereby  represents and warrants to
               the Limited Partners that:

                    (a) The  Partnership  is a  limited  partnership  formed  in
               accordance with and validly  existing under the Act and the other
               applicable laws of the State of California;

                  (b) The interests in the  Partnership of the Limited  Partners
         will have been duly  authorized  or created and validly  issued and the
         Limited  Partners shall have no personal  liability to contribute money
         to the Partnership other than the amounts


                                                        -7-


<PAGE>



         agreed to be  contributed  by them in the  manner  and on the terms set
         forth in this Agreement,  subject,  however, to such limitations as may
         be imposed under the Act;

                  (c) Except as disclosed  in the  Memorandum  or  documentation
         prepared in connection with a Dilution Offering,  no material breach or
         default adverse to the Partnership  exists under the terms of any other
         material agreement affecting the Partnership; and

                    (d) The General Partner is a California limited  partnership
               formed and existing under the laws of the State of California.

                    10.2 The General  Partner  hereby  covenants  to the Limited
               Partners that:

                    (a) It will at all  times  act in a  fiduciary  manner  with
               respect to the Partnership and the Limited Partners;

                    (b) Except as  provided  in Article 19, it will serve as the
               General  Partner  of the  Partnership  until the  Partnership  is
               terminated without reconstitution; and

                  (c) It will cause the  Partnership  to carry  adequate  public
         liability,  property  damage and other insurance as is customary in the
         business to be engaged in by the Partnership.

                  11.      ADMISSION OF LIMITED PARTNERS.
                           -----------------------------

                  The  General  Partner may permit the offer and sale of limited
partnership  interests on the terms and conditions provided in the Memorandum or
future  Dilution  Offerings and may admit persons  subscribing  for interests as
Limited  Partners in the  Partnership  on the terms and  conditions set forth in
this Article 11.

                  (a) The General  Partner  shall have approved of the admission
         of said person in writing on such terms and  conditions  as the General
         Partner shall determine;

                  (b)  Said  person  shall  have  executed  such   documents  or
         instruments  as the General  Partner may deem necessary or desirable to
         effect his or her admission as a Limited Partner;

                    (c) Said person  shall have  accepted and adopted all of the
               terms and provisions of this Agreement, as then amended;

                    (d) Said  person  (if a  corporation)  shall  deliver to the
               General  Partner a certified copy of a resolution of its Board of
               Directors authorizing it to become a


                                                        -8-


<PAGE>



         Limited Partner under the terms and conditions of this Agreement; and

                  (e) Said person,  upon request by the General  Partner,  shall
         pay such reasonable  expenses as may be incurred in connection with its
         admission as a Limited Partner.

                  12.      CAPITAL ACCOUNTS.
                           ----------------

                  A Capital  Account shall be  established  for each Partner and
shall at all times be determined  and  maintained  in accordance  with the Final
Treasury  Regulations  under  Section  704(b)  of the  Code,  as the same may be
amended.  A Partner  shall not be entitled  to  withdraw  any part of his or her
Capital Account or to receive any distribution  from the Partnership,  except as
provided in Articles 14 and 25.

                  (a)      Each Partners' Capital Account shall be increased by:

                    (i) The amount of his or her Capital  Contribution  pursuant
               to Article 7; and

                    (ii) The amount of Profits  allocated to him or her pursuant
               to Article 13; and

                           (iii) The Partner's pro rata share (determined in the
                  same  manner as such  Partner's  share of  Profits  and Losses
                  allocated pursuant to Article 13 hereof) of any income or gain
                  exempt from tax.

                  (b)      Each Partner's Capital Account shall be decreased by:

                    (i) The amount of Losses allocated to him or her pursuant to
               Article 13; and

                    (ii) The amount of Partnership Cash Flow,  Partnership Sales
               Proceeds and Partnership  Refinancing Proceeds distributed to him
               or her pursuant to Article 14; and

                           (iii)  The  Partner's  pro rata  share  of any  other
                  expenditures  of the  Partnership  which are not deductible in
                  computing  Partnership  Profits  or  Losses  and which are not
                  added to the tax basis of any Partnership property, including,
                  without   limitation,   expenditures   described   in  Section
                  705(a)(2)(B) of the Code. The Partner's pro rata share of such
                  expenditures  shall be  determined  in the same manner as such
                  Partner's  share of Profits and Losses  allocated  pursuant to
                  Article 13.


                                                        -9-


<PAGE>



                  13.      ALLOCATIONS

                    (a) Nonrecourse Deductions.  Nonrecourse Deductions shall be
               allocated among the Partners in accordance with their  respective
               Percentage Interests.

                  (b) Partner  Nonrecourse  Deductions.  Any Partner Nonrecourse
         Deductions  shall be  specially  allocated to the Partner who bears the
         economic risk of loss with respect to the Partner  Nonrecourse  Debt to
         which  such  Partner   Nonrecourse   Deductions  are   attributable  in
         accordance with Treasury Regulations Section 1.704-2(i).

                  (c)      Profits and Losses.

                           (i) The Profits and Losses of the  Partnership  shall
                  be  allocated  among the  Partners  in  accordance  with their
                  respective  Percentage  Interests.  In allocating  Profits and
                  Losses, Net Gains and Losses from Capital Transactions (a part
                  of Profits and Losses), if any, shall be allocated first.

                           (ii) In no event shall Losses be allocated under this
                  Article  13(c) to a Limited  Partner if and to the extent that
                  such  allocation  would cause,  as of the end of the Year, the
                  negative balance in such Limited  Partner's Capital Account to
                  exceed such Limited  Partner's  share of  Partnership  Minimum
                  Gain plus such  Limited  Partner's  share,  if any, of Partner
                  Minimum  Gain.  Any  Losses  which  are not  allocated  to the
                  Limited  Partner by virtue of the application of the preceding
                  sentence  shall  be  allocated  to the  General  Partner.  For
                  purposes of this Article  13(c), a Partner's  Capital  Account
                  shall be treated as reduced by Qualified  Income  Offset Items
                  as provided in Article 13(d)(iii).  All items of income, gain,
                  loss,  deduction,  or  credit  shall be  allocated  among  the
                  Partners   proportionately.   Further,   notwithstanding   the
                  foregoing,  after giving effect to the special  allocations in
                  Article 13(d), the General Partner shall be allocated at least
                  1% of all items of income, gain, loss, deduction or credit.

                    (d) Special  Allocations.  The following special allocations
               shall be made:


                           (i) Partnership Minimum Gain Chargeback.  If there is
                  a net  decrease in  Partnership  Minimum Gain during any Year,
                  each Partner shall be specially allocated items of Partnership
                  income and gain for such Year (and, if  necessary,  subsequent
                  Years) in an amount equal to such  Partner's  share of the net
                  decrease in Partnership


                                                       -10-


<PAGE>



                  Minimum  Gain,   determined   in   accordance   with  Treasury
                  Regulations Section 1.704-2(g)(2). Allocations pursuant to the
                  previous   sentence   shall  be  made  in  proportion  to  the
                  respective  amounts  required to be allocated to each Partner.
                  The items to be so allocated shall be determined in accordance
                  with Treasury  Regulations  Section 1.704- 2(f).  This Article
                  13(d)(i)  is   intended  to  comply  with  the  minimum   gain
                  chargeback  requirement in such Section of the Regulations and
                  shall be interpreted consistently therewith.

                           (ii) Partner Minimum Gain Chargeback. Notwithstanding
                  any  other   provision  of  this  Article  13  except  Article
                  13(d)(i),  if there is a net decrease in Partner  Minimum Gain
                  attributable  to a Partner  Nonrecourse  Debt during any Year,
                  each  Partner  who has a share  of the  Partner  Minimum  Gain
                  attributable to such Partner  Nonrecourse Debt,  determined in
                  accordance with Treasury Regulations Section 1.704-2(f), shall
                  be specially  allocated  items of Partnership  income and gain
                  for such Year  (and,  if  necessary,  subsequent  Years) in an
                  amount  equal to such  Partner's  share of the net decrease in
                  Partner Minimum Gain attributable to such Partner  Nonrecourse
                  Debt, to the extent  required by and  determined in accordance
                  with Treasury Regulations Section  1.704-2(i)(4).  Allocations
                  pursuant to the previous  sentence shall be made in proportion
                  to the  respective  amounts  required to be  allocated to each
                  Partner pursuant  thereto.  The items to be so allocated shall
                  be determined in accordance with Treasury  Regulations Section
                  1.704-2(i)(4).  This  Article  13(d)(ii) is intended to comply
                  with the minimum gain  chargeback  requirement in such Section
                  of the  Regulations  and  shall  be  interpreted  consistently
                  therewith.

                           (iii)  Qualified   Income  Offset.   If  any  Partner
                  unexpectedly   receives   any   adjustment,    allocation   or
                  distribution   described  in  Treasury   Regulations   Section
                  1.704-1(b)(2)(ii)(d)(4)  through (6) which causes or increases
                  a deficit balance in such Partner's  Capital Account (adjusted
                  for  this   purpose  in  the  manner   provided   in  Treasury
                  Regulations    Section    1.704-1(b)(2)(ii)(d)),    items   of
                  Partnership  income and gain shall be  specially  allocated to
                  each  such  Partner  in an amount  and  manner  sufficient  to
                  eliminate,  to the extent  required  by the  Regulations,  the
                  deficit   Capital  Account  of  such  Partner  as  quickly  as
                  possible, provided that an allocation pursuant to this Article
                  13(b)  shall  be made  if and  only to the  extent  that  such
                  Partner would have a deficit  Capital  Account after all other
                  allocations   provided  for  in  this  Article  13  have  been
                  tentatively  made as if this  Article  13(b)  were  not in the
                  Agreement. This provision is


                                                       -11-


<PAGE>



                  intended  to be a  "qualified  income  offset,"  as defined in
                  Treasury   Regulations  Section   1.704-1(b)(2)(ii)(d),   such
                  Regulation   being   specifically   incorporated   herein   by
                  reference.

                           (iv) Sales Commission.  The Sales Commission shall be
                  allocated  to the  Units  which  are not  held by the  General
                  Partner and its Affiliates and are acquired in the Offering in
                  proportion to the respective capital contributions represented
                  by such Units (i.e.,  $250 in Sales  Commissions per each such
                  Unit).  The purpose of this  Article  13(c)(iv) is to allocate
                  the Sales  Commission to those  Partners who actually bore the
                  burden of paying the Sales Commission.

                    (e)  Ordering  Provision.  In  applying  the  provisions  of
               Articles 13 and 14 with respect to distributions and allocations,
               the following ordering of priorities shall apply:

                    (i)  Capital  Accounts  shall be  deemed  to be  reduced  by
               Qualified Income Offset Items.

                    (ii) Capital  Accounts shall be reduced by  Distributions of
               Partnership Cash Flow under Article 14(a).

                    (iii) Capital  Accounts shall be reduced by Distributions of
               Partnership Sales Proceeds and Partnership  Refinancing  Proceeds
               under Article 14(b).

                    (iv) Capital Accounts shall be increased by any Minimum Gain
               Chargeback under Articles 13(d)(i) and (ii).

                    (v) Capital  Accounts  shall be increased  by any  Qualified
               Income Offset under Article 13(d)(iii).

                    (vi) Capital  Accounts  shall be reduced by  allocations  of
               Nonrecourse Deductions under Article 13(a).

                           (vii)   Capital   Accounts   shall  be   reduced   by
                  allocations of Partner  Nonrecourse  Deductions  under Article
                  13(b).

                           (viii)   Capital   Accounts  shall  be  increased  by
                  allocations of Profits under Article 13(c).

                    (ix) Capital  Accounts  shall be reduced by  allocations  of
               Losses under Article 13(c).


                                                       -12-


<PAGE>



                  To the maximum extent permitted under the Code, allocations of
         Profits  and Losses  shall be modified  so that the  Partners'  Capital
         Accounts  reflect the amount they would have  reflected if  adjustments
         required by Articles 13(d)(i), (ii) and (iii) had not occurred.

                  (f)  Allocations  Between  Transferor and  Transferee.  In the
         event of the transfer (other than the pledges of the General  Partner's
         interest  permitted  by Article 19 or  Permitted  Pledges  described in
         Article  17.2(b))  of all or  any  part  of a  Partner's  interest  (in
         accordance with the provisions of this Agreement) in the Partnership at
         any time other  than at the end of a Year,  or the  admission  of a new
         Partner  (in  accordance  with  the  terms  of  this  Agreement),   the
         transferring  Partner  or new  Partner's  share  of  the  Partnership's
         income,  gain,  loss,  deductions  and  credits,  as computed  both for
         accounting  purposes  and for  federal  income tax  purposes,  shall be
         allocated between the transferor Partner and the transferee Partner (or
         Partners),  or the new Partner and the other Partners,  as the case may
         be, in the same  ratio as the  number of days in such Year  before  and
         after the date of the transfer or admission; provided, however, that if
         there  has  been a sale  or  other  disposition  of the  assets  of the
         Partnership  (or any part thereof)  during such Year,  then the General
         Partner may elect, in its sole discretion,  to treat the periods before
         and after the date of the transfer or  admission as separate  Years and
         allocate the Partnership's net income,  gain, net loss,  deductions and
         credits for each of such deemed  separate  Years.  Notwithstanding  the
         foregoing, the Partnership's "allocable cash basis items," as that term
         is used in Section  706(d)(2)(B)  of the Code,  shall be  allocated  as
         required  by  Section   706(d)(2)  of  the  Code  and  the  regulations
         thereunder.

                  (g) Tax  Withholding.  The Partnership  shall be authorized to
         pay, on behalf of any  Partner,  any amounts to any  federal,  state or
         local taxing  authority,  as may be necessary  for the  Partnership  to
         comply with tax withholding  provisions of the Code or the other income
         tax or  revenue  laws  of any  taxing  authority.  To  the  extent  the
         Partnership  pays any such  amounts  that it may be  required to pay on
         behalf  of  a  Partner,  such  amounts  shall  be  treated  as  a  cash
         distribution  to such  Partner  and shall  reduce the amount  otherwise
         distributable to such Partner.

                  14.      DISTRIBUTIONS.
                           -------------

                  (a)  Distribution of Partnership  Cash Flow.  Partnership Cash
         Flow shall be distributed to the Partners  within 60 days after the end
         of each Year, or earlier in the discretion of the General  Partner,  in
         proportion  to their  respective  Percentage  Interests  at the time of
         distribution.

                    (b)  Distribution  of Partnership  Refinancing  Proceeds and
               Partnership Sales Proceeds.  Partnership Refinancing Proceeds and
               Partnership  Sales  Proceeds shall be distributed to the Partners
               within 60 days of the Capital Transaction giving


                                                       -13-


<PAGE>



         rise to such  proceeds,  or earlier in the  discretion  of the  General
         Partner, in proportion to their respective  Percentage Interests at the
         time of distribution.

                  (c)  Distribution  in  Liquidation.  Upon  liquidation  of the
         Partnership,  all of the  Partnership's  property  shall  be  sold  and
         Profits and Losses allocated accordingly. Proceeds from the liquidation
         of the Partnership shall be distributed in accordance with Article 25.

                  l5.      RIGHTS AND OBLIGATIONS OF LIMITED PARTNERS.
                           ------------------------------------------

                  15.1  Management.  The Limited Partners shall not take part in
the management of the business,  nor transact any business for the  Partnership,
nor  shall  they  have  power  to  sign  for or to  bind  the  Partnership.  The
Partnership may,  however,  contract with one or more Limited Partners to act as
the local medical  director(s) of the Lithotripsy System. No Limited Partner may
withdraw from the Partnership except as expressly permitted herein.

                  15.2 Operation of  Lithotripsy  System.  The Limited  Partners
shall  not  operate  or  utilize  the  Partnership  Lithotripsy  System or other
Partnership  equipment except pursuant to (i) an agreement with the Partnership;
or (ii) any other arrangement specifically approved by the General Partner.

                  15.3 Outside Activities.  The Limited Partners agree that they
owe fiduciary  duties to the  Partnership  and, as a  consequence,  each Limited
Partner (that is not the General Partner or an Affiliate of the General Partner)
agrees that (s)he shall not engage in "Outside Activities" (as defined below) in
the "Market  Area" (as defined  below)  while(s)he  is a Limited  Partner in the
Partnership  and shall  otherwise be subject to the  provisions  of this Article
15.3.  The phrase  "Outside  Activities"  means  directly or indirectly  owning,
leasing or  subleasing  a  lithotripter  (or any similar  equipment or competing
devices  used  for  treating  renal  or  biliary  stone  disease)  or any  other
therapeutic  equipment  acquired by the Partnership;  provided that an ownership
interest in the General Partner or an Affiliate of the General Partner shall not
constitute an Outside  Activity.  Prohibited  indirect  ownership  shall include
without  limitation  the  direct or  indirect  ownership  of any  interest  in a
business  venture  (through stock  ownership,  partnership  interest  ownership,
ownership by or through a close family  member,  or as otherwise  determined  in
good faith by the General  Partner)  involving the ownership,  purchase,  lease,
sublease,  promotion,  management  or  operation of a  lithotripter  (or similar
equipment or competing devices used for treating renal or biliary stone disease)
or other competing  device or equipment,  unless the General Partner  determines
that such  activity  by the  Limited  Partners  is not  detrimental  to the best
interests of the  Partnership.  Notwithstanding  the above,  Outside  Activities
shall not include (i) ownership of less than 1% of the capital stock (calculated
on a fully  diluted  basis) of a  corporation  whose stock is publicly  owned or
regularly  traded on any public  exchange,  (ii) any  ownership  interest  in an
entity  engaging  in an  Outside  Activity  acquired  before  the  date  hereof;
provided,  that  the  Limited  Partner  may not  increase  or  enhance  any such
previously held  investment  during the term of the  Partnership,  and (iii) any
other


                                                       -14-


<PAGE>



activity  determined by the General Partner,  in its sole discretion,  not to be
detrimental to the best interests of the Partnership.

                  Upon  the  termination  or  transfer  of a  Limited  Partner's
interest in the  Partnership  for any reason,  including a transfer  pursuant to
Article 18.3 hereof, the withdrawing  Limited Partner shall not, for a period of
two (2) years following the date of withdrawal, engage in any Outside Activities
in any "Market Area" in which the Partnership is transacting  business or within
the prior twelve months has transacted  business (the "Restricted  Facilities").
For the purposes of this Article 15.3, the term "Market Area" shall mean (i) the
area within a fifty (50) mile  radius of any  Restricted  Facility,  but if such
area is determined by a court of competent jurisdiction to be too broad, then it
shall  mean (ii) the area  within a thirty  (30) mile  radius of any  Restricted
Facility, but if such area is determined by a court of competent jurisdiction to
be too broad then it shall mean (iii) the area within a fifteen (15) mile radius
of any Restricted Facility.

                  In the event a Limited Partner wishes and intends to engage in
an Outside  Activity in a Market Area, he or she must provide  written notice of
such intent to the General  Partner  prior to engaging in the Outside  Activity.
The  written  notice  shall be deemed an  election  by the  Limited  Partner  to
withdraw from the Partnership (the "Notice of  Withdrawal"),  and shall give the
General  Partner the purchase  rights as provided in Article 18.3 hereof.  After
the Notice of Withdrawal,  the former  Limited  Partner may engage in an Outside
Activity in the Market Area only after waiting the period of two years specified
in this  Article  15.3.  In the  event of  breach  of the  waiting  period,  the
Partnership  shall be entitled  to any remedy at law or equity  with  respect to
such breach, including without limitation an injunction or suit for damages.

                  If a Limited  Partner during his or her  participation  in the
Partnership  engages in an  Outside  Activity  in a Market  Area  without  first
notifying  the General  Partner in violation of this Article  15.3,  the Limited
Partner  shall be deemed to have  given a Notice of  Withdrawal  on the date the
General Partner first becomes aware of the Limited Partner's Outside Activity in
the Market Area.  Upon  receiving a Limited  Partner's  Notice of  Withdrawal or
equivalent  thereof,  the Partnership may invoke the purchase rights provided in
Article  18.3  and  shall be  entitled  to any  other  remedy  at law or  equity
including without limitation an injunction or suit for damages.

                  15.4  Disclosure  of  Confidential  Information.  Each Limited
Partner acknowledges and agrees that his or her participation in the Partnership
under this Agreement necessarily involves his or her understanding of and access
to certain trade secrets and other  confidential  information  pertaining to the
business of the Partnership.  Accordingly,  each Limited Partner (other than the
General   Partner  and  its  Affiliates  that  may  also  hold  Limited  Partner
Partnership  Interests) agrees that at all times during his or her participation
in the Partnership as a Limited Partner and thereafter, (s)he will not, directly
or indirectly, without the express written authority of the Partnership,  unless
required by law or directed by a applicable legal authority having  jurisdiction
over  the  Limited  Partner,  disclose  or use for the  benefit  of any  person,
corporation  or other  entity  (other  than  the  Partnership),  or the  Limited
Partner, (i) any trade, technical, operational, management or other secrets, any
patient or customer  lists or other  confidential  or secret data,  or any other
proprietary,


                                                       -15-


<PAGE>



confidential or secret  information of the Partnership or (ii) any  confidential
information concerning any of the financial  arrangements,  financial condition,
hospital  or  physician  contracts,  third  party  payor  arrangements,  quality
assurance  and  outcome  analysis  programs,  competitive  status,  customer  or
supplier matters, internal organizational matters, technical abilities, or other
business affairs of or relating to the Partnership.  The Limited Partners (other
than the General  Partner and its Affiliates  that may also hold Limited Partner
Partnership  Interests)  acknowledge  that  all  of  the  foregoing  constitutes
proprietary information,  which is the exclusive property of the Partnership. In
the event of breach of this Article 15.4 as determined  by the General  Partner,
the Partnership shall be entitled to any remedy at law or equity with respect to
such breach, including without limitation, an injunction or suit for damages.

                  16.      LIMITED LIABILITY.
                           -----------------

                  No Limited Partner shall be required to make any  contribution
to the  capital of the  Partnership  except as set forth in Article 7, nor shall
any Limited  Partner in his or her capacity as such,  be bound by, or personally
liable for, any expense,  liability or obligation of the  Partnership  except to
the extent of his or her (i) interest in the  Partnership;  (ii)  Guaranties  of
Partnership  obligations;  and (iii) obligation to return  distributions made to
him or her under certain circumstances as required by the Act.

                  17.      TRANSFER OF INTERESTS AND ADMISSION OF PARTNERS.
                           -----------------------------------------------

                  17.1     Transferability.
                           ---------------

                  (a) The  term  "transfer"  when  used in this  Agreement  with
         respect to a Partnership  Interest includes a sale,  assignment,  gift,
         pledge,  exchange  or any other  disposition  (but does not include the
         issuance of new Partnership Interests pursuant to a Dilution Offering);

                    (b) Except as otherwise provided herein, the General Partner
               shall  not at  any  time  transfer  or  assign  its  interest  or
               obligation as General Partner;

                  (c) The Partnership  Interest of any Limited Partner shall not
         be  transferred,  in whole or in part,  except in  accordance  with the
         conditions and limitations set forth in Articles 17.2 or 18;

                  (d) The  transferee of a Partnership  Interest by  assignment,
         operation of law or otherwise,  shall have only the rights,  powers and
         privileges  enumerated in Article 17.3 or otherwise provided by law and
         may not be admitted to the  Partnership as a Limited  Partner except as
         provided in Article 17.4 or as a General  Partner except as provided in
         Article 17.5;


                                                       -16-


<PAGE>



                  (e) Notwithstanding any provision herein to the contrary,  the
         Partnership  Agreement  shall  in  no  way  restrict  the  issuance  or
         transfers of stock of the General  Partner or the merger of the General
         Partner with another person or entity; and

                  (f) Notwithstanding any provision herein to the contrary,  the
         issuance of Partnership  Interests  pursuant to a Dilution Offering and
         the admission of new Limited Partners  pursuant to a Dilution  Offering
         shall be governed by the provisions of Article 7.4 of this Agreement.

                  17.2     Restrictions on Transfers by Limited Partners.
                           ---------------------------------------------

                  (a) All or part of a Partnership  Interest may be  transferred
         by a  Limited  Partner  only  with the prior  written  approval  of the
         General  Partner,  which  approval may be granted or denied in the sole
         discretion of the General Partner.

                  (b) The General  Partner  shall not approve any  transfer of a
         Partnership  Interest,  except a pledge of any Partnership  Interest by
         the General Partner to any bank,  insurance  company or other financial
         institution to secure payment of indebtedness  (a "Permitted  Pledge"),
         or otherwise  unless the proposed  transferee  shall have furnished the
         General Partner with a sworn statement that:

                    (i) The proposed  transferee  proposes to acquire his or her
               Partnership Interest as a principal,  for investment and not with
               a view to resale or distribution;

                           (ii) The proposed  transferee meets such requirements
                  regarding sophistication,  income and net worth as required by
                  applicable state and federal securities laws;

                           (iii) The proposed  transferee has met such net worth
                  and income  suitability  standards as have been established by
                  the General Partner;

                           (iv)  The   proposed   transferee   recognizes   that
                  investment in the Partnership  involves  certain risks and has
                  taken  full  cognizance  of and  understands  all of the  risk
                  factors related to the purchase of a Partnership Interest; and

                    (v) The proposed  transferee has met all other  requirements
               of the General Partner for the proposed transfer.

                    (c) Other than in the case of a Permitted Pledge, a transfer
               of a Partnership  Interest may be made only if, prior to the date
               thereof, the Partnership


                                                       -17-


<PAGE>



         upon request  receives an opinion of counsel,  satisfactory in form and
         substance  to the General  Partner,  that  neither the offering nor the
         proposed transfer will require registration under federal or applicable
         state securities laws or regulations.

                  17.3 Rights of Transferee.  Unless admitted to the Partnership
in accordance  with Article 17.4, the transferee of a Partnership  Interest or a
part thereof or any right,  title or interest  therein  shall not be entitled to
any of the rights,  powers, or privileges of his or her predecessor in interest,
except that (s)he  shall be entitled to receive and be credited or debited  with
his or her proportionate share of Partnership income,  gains,  Profits,  Losses,
deductions, credits or distributions.

                  17.4  Admission  of  Limited  Partners.  Except  as  otherwise
provided in Article 18, the General Partner, or the transferee of all or part of
the Partnership  Interest of either a General Partner or a Limited Partner,  may
be admitted to the  Partnership  as a Limited  Partner  upon  furnishing  to the
General Partner all of the following:

                  (a) The  written  approval of a Majority in Interest of all of
         the Limited  Partners  (except the assignor  Partner),  or the assignor
         Partner  alone,  which  approval  may be  granted or denied in the sole
         discretion of such Partners or Partner (as the case may be);

                    (b) The  written  approval  of the  General  Partner,  which
               approval may be granted or denied in the sole  discretion  of the
               General Partner;

                  (c) Acceptance, in a form satisfactory to the General Partner,
         of all the  terms  and  conditions  of  this  Agreement  and any  other
         documents  required in connection with the operation of the Partnership
         pursuant to the terms of this Agreement;

                    (d) A  properly  executed  power of  attorney  substantially
               identical to that contained in Article 38;

                    (e) Such other  documents or  instruments as may be required
               in order to effect his or her admission as a Limited Partner; and

                    (f) Payment of such  reasonable  expenses as may be incurred
               in connection with his or her admission as a Limited Partner.

                    17.5 Admission of General  Partners.  A Limited Partner,  or
               the transferee of all or part of the Partnership  Interest of the
               General Partner,  may be admitted to the Partnership as a general
               partner  upon  furnishing  to  the  General  Partner  all  of the
               following:



                                                       -18-


<PAGE>



                  (a) The  written  consent of both the  General  Partner  and a
         Majority  in Interest of the  Limited  Partners,  which  consent may be
         granted or denied in the sole discretion of the Partners;

                  (b) Such financial statements,  guarantees or other assurances
         as the General  Partner  may require  with regard to the ability of the
         proposed  general  partner to fulfill the  financial  obligations  of a
         general partner hereunder;

                  (c) Acceptance,  in form  satisfactory to the General Partner,
         of all the  terms  and  provisions  of  this  Agreement  and any  other
         documents  required in connection with the operation of the Partnership
         pursuant to the terms of this Agreement;

                    (d) A  certified  copy  of a  resolution  of  its  Board  of
               Directors  (if it is a  corporation)  authorizing  it to become a
               general partner under the terms and conditions of this Agreement;

                    (e) A power  of  attorney  substantially  identical  to that
               contained in Article 38;

                    (f) Such other  documents or  instruments as may be required
               in  order  to  effect  his,  her or its  admission  as a  general
               partner; and

                    (g) Payment of such  reasonable  expenses as may be incurred
               in  connection  with  his,  her or  its  admission  as a  general
               partner.

                  Notwithstanding  the above,  a transferee  that controls or is
controlled by the General Partner or one or more of its Affiliates that receives
all or part of the  Partnership  Interest of the General Partner may be admitted
to the  Partnership as a general  partner upon complying with all the provisions
of Article  17.5  except for  subparagraph  17.5(a).  As long as the  transferee
either  controls or is controlled  by the General  Partner or one or more of its
Affiliates,  no  Limited  Partner  consents  will  be  required  to  admit  such
transferee as a general partner to the Partnership.

                  17.6  Amendment  of  Certificate  of Limited  Partnership  and
Qualification.   The  General   Partner  shall  take  all  steps  necessary  and
appropriate to prepare and record any  amendments to the  Certificate of Limited
Partnership, as may be necessary or appropriate from time to time to comply with
the requirements of the Act, including,  without limitation,  upon the admission
to the Partnership of any general partner  pursuant to the provisions of Article
17.5, and may for this purpose  exercise the power of attorney  delivered to the
General Partner pursuant to Article 17.5 or 38. In addition, the General Partner
shall take all steps necessary and appropriate to prepare and record any and all
documents  necessary to qualify the Partnership to do business in  jurisdictions
where the Partnership is doing business,  and may for this purpose  exercise the
power of attorney  delivered to the General  Partner  pursuant to Articles 17.4,
17.5 or 38.


                                                       -19-


<PAGE>



                  17.7 Fundamental  Changes.  In the event a plan is approved by
the General Partner and a Majority in Interest of the Limited Partners providing
for the  merger or  consolidation  of the  Partnership  with  another  person or
entity,  or the sale of all or substantially  all of the Partnership  Interests,
including  without  limitation the exchange of Partnership  Interests for equity
interests  in  another  person or entity or for cash or other  consideration  or
combination  thereof,  then and in such  event,  the Limited  Partners  shall be
obligated to take or refrain  from  taking,  as the case may be, such actions as
the plan may provide, including, without limitation, executing such instruments,
and providing such information as the General Partner shall reasonably  request.
Any plan  described  in this  Article  17.7 may also effect an  amendment to the
Partnership Agreement or the adoption of a new partnership agreement as provided
in Section  15678.2(e)  of the Act.  The plan may also  provide that the General
Partner  and  its  Affiliates  shall  receive  fees  for  services  rendered  in
connection  with  the  operation  of the  Partnership  or any  successor  entity
following  the  consummation  of the  transactions  described  in the plan,  and
neither the  Partnership nor the Partners shall have any right by virtue of this
Agreement in the income derived therefrom. Any securities or other consideration
to be distributed  to the Partners  pursuant to the plan shall be distributed in
the  manner  set forth in Article  25(c) as though  the  Partnership  were being
liquidated.  For this purpose only,  the fair market value of the  securities or
other  consideration  to be  received  pursuant  to the plan shall be treated as
"Profits"  and the capital  accounts of the  Partners  shall be increased in the
manner  provided  in Article  12(a)(ii).  No Partner  shall be  entitled  to any
dissent,  appraisal or similar rights in connection with a plan  contemplated by
this Article 17.7.

                  17.8 Withdrawal of Initial Limited Partner.  Upon the date the
first Limited  Partner is admitted to the Partnership in accordance with Article
11 of this  Agreement,  the Initial  Limited  Partner  shall  withdraw  from the
Partnership,  and thereupon his Capital  Contribution  shall be returned and his
Partnership Interest canceled and reallocated to the Limited Partners.

                  18.      OPTIONAL PURCHASE OF LIMITED PARTNERSHIP INTERESTS
                           --------------------------------------------------
                           ON CERTAIN EVENTS.
                           -----------------

                  18.1 Death. Upon the death of a Limited Partner,  the deceased
Limited  Partner's   executor,   administrator,   or  other  legal  or  personal
representative  shall give written  notice of that fact to the General  Partner.
The General Partner shall have the option to purchase at the Closing (as defined
below) the Partnership Interest of the deceased Limited Partner (whose executor,
administrator  or other  legal or  personal  representative  shall  then  become
obligated  to sell such  Partnership  Interest) at the price  determined  in the
manner  provided  in  Article  18.7  of  this  Agreement  and on the  terms  and
conditions provided in Article 18.8 of this Agreement. The General Partner shall
have a period of thirty (30) days  following  the date of notice of the death of
the Limited Partner (the "Option  Period") within which to notify in writing the
deceased Limited  Partner's  executor,  administrator or other legal or personal
representative,  whether the General Partner wishes to purchase all or a portion
of the  Partnership  Interest of the deceased  Limited  Partner.  If the General
Partner  does not elect to  purchase  the  entire  Partnership  Interest  of the
deceased  Limited  Partner before the expiration of the Option Period and in the
manner provided  herein,  the portion of the Partnership  Interest not purchased
shall be held by the deceased Limited Partner's executor,


                                                       -20-


<PAGE>



administrator  or  other  legal  representative  pursuant  to the  terms of this
Agreement. The General Partner, in its sole discretion,  may elect to assign its
rights to purchase  the  Partnership  Interest of the deceased  Limited  Partner
under this Article 18.1 to the  Partnership  and, in such case, the  Partnership
shall have the same rights as provided  for the General  Partner in this Article
18.1.

                  18.2  Bankruptcy,  Insolvency  or  Assignment  for  Benefit of
Creditors of a Limited  Partner.  In the event that an  involuntary or voluntary
proceeding  under the  Federal  Bankruptcy  Code,  as  amended,  is filed for or
against any Limited Partner,  or if any Limited Partner shall make an assignment
for the benefit of his  creditors,  or if any Limited  Partner has a receiver or
custodian  appointed for his assets,  or any Limited Partner  generally fails to
pay his debts when due, the insolvent  Limited Partner shall give written notice
(the "Notice of Insolvency")  to the General Partner of the  commencement of any
such  proceeding  or the  occurrence of such event within five days of the first
notice to him of such  commencement  or  occurrence  of such event.  The General
Partner shall have the option to purchase at the Closing (as defined  below) the
Partnership  Interest of the  insolvent  Limited  Partner  (which the  insolvent
Limited Partner or his trustee,  custodian,  receiver or other personal or legal
representative,  as the case may be, shall then become obligated to sell) at the
price determined in the manner provided in Article 18.7 of this Agreement and on
the terms and conditions provided in Article 18.8 of this Agreement. The General
Partner shall have a period of thirty (30) days following the date of the Notice
of  Insolvency  (the  "Option  Period")  within  which to notify in writing  the
insolvent Limited Partner or his trustee, custodian, receiver, or other legal or
personal representative, whether the General Partner wishes to purchase all or a
portion of the Partnership  Interest of the insolvent  Limited  Partner.  If the
General  Partner does not elect to purchase the entire  Partnership  Interest of
the insolvent  Limited Partner before the expiration of the Option Period and in
the  manner  provided  herein,  the  portion  of the  Partnership  Interest  not
purchased  shall  be held by the  insolvent  Partner,  his  trustee,  custodian,
receiver or other legal or personal representative pursuant to the terms of this
Agreement. The General Partner, in its sole discretion,  may elect to assign its
rights to purchase  the  Partnership  Interest of an insolvent  Limited  Partner
under this Article 18.2 to the  Partnership  and, in such case, the  Partnership
shall have the same rights as provided  for the General  Partner in this Article
18.2.

                  18.3 Breach of Article 15.3. In the event the General  Partner
either  receives a Notice of  Withdrawal as provided in Article 15.3 or receives
notice of a breach of Article 15.3 by or with respect to a Limited  Partner (the
"Competing  Limited  Partner"),  the  General  Partner  may  elect,  in its sole
discretion,  to treat such event as a default  under this  Agreement and enforce
the  provisions of this Article 18.3. If the General  Partner  elects to enforce
the  provisions  of this Article  18.3,  the General  Partner shall give written
notice of such  election  (the  "Notice of Default")  to the  Competing  Limited
Partner  within 180 days of the date the  General  Partner  first  received  the
Notice of  Withdrawal or notice of the  defaulting  event.  The General  Partner
shall  have the  option to  purchase  at the  Closing  (as  defined  below)  the
Partnership  Interest of the  Competing  Limited  Partner  (which the  Competing
Limited Partner shall then become  obligated to sell) at the price determined in
the manner  provided  in  Article  18.7 of this  Agreement  and on the terms and
conditions provided in Article 18.8 of this Agreement. The General Partner shall
have a period of  thirty  (30) days  following  the date it sends the  Notice of
Default (the "Option Period") within which to notify in


                                                       -21-


<PAGE>



writing  the  Competing  Limited  Partner,  whether  the  Partnership  wishes to
purchase all or a portion of the Partnership  Interest of the Competing  Limited
Partner.  If  the  General  Partner  does  not  elect  to  purchase  the  entire
Partnership  Interest of the Competing  Limited Partner before the expiration of
the  Option  Period  and in the  manner  provided  herein,  the  portion  of the
Partnership  Interest  not  purchased  shall  be held by the  Competing  Limited
Partner  pursuant to the terms of this Agreement.  The General  Partner,  in its
sole  discretion,  may elect to assign its rights to  purchase  the  Partnership
Interest  of a  Competing  Limited  Partner  under  this  Article  18.3  to  the
Partnership  and, in such case,  the  Partnership  shall have the same rights as
provided for the General Partner in this Article 18.3.

                  18.4  Domestic  Proceeding.  In the  event  that a spouse of a
Limited Partner  commences  against a Limited  Partner,  or a Limited Partner is
named in, a Domestic  Proceeding,  the Limited Partner shall give written notice
(the "Notice of Domestic Proceeding") to the General Partner of the commencement
of any such  proceeding  within  five  days of the  first  notice to him of such
commencement.  The  General  Partner  shall have the option to  purchase  at the
Closing  (as defined  below) the  Partnership  Interest  of the Limited  Partner
involved in the Domestic Proceeding (which the Limited Partner shall then become
obligated to sell),  at the price  determined in the manner  provided in Article
18.7 of this Agreement and on the terms and conditions  provided in Article 18.8
of this  Agreement.  The General Partner shall have a period of thirty (30) days
following the date of the Notice of Domestic  Proceeding  (the "Option  Period")
within which to notify in writing the Limited  Partner  involved in the Domestic
Proceeding,  whether the General  Partner wishes to purchase all or a portion of
the Partnership  Interest of such Limited  Partner.  If the General Partner does
not elect to purchase the Partnership  Interest of the Limited Partner  involved
in the Domestic Proceeding before the expiration of the Option Period and in the
manner provided  herein,  the portion of the Partnership  Interest not purchased
shall be held by such Limited  Partner  pursuant to the terms of this Agreement.
The General Partner,  in its sole discretion,  may elect to assign its rights to
purchase  the  Partnership  Interest  of the  Limited  Partner  involved  in the
Domestic  Proceeding  under this  Article 18.4 to the  Partnership  and, in such
case,  the  Partnership  shall have the same rights as provided  for the General
Partner in this Article 18.4.

                  18.5 Divestiture  Option.  If state or federal  regulations or
laws are enacted or applied, or if any other legal developments occur, which, in
the opinion of the General Partner  adversely  affect (or potentially  adversely
affect) the operation of the Partnership  (e.g., the enactment or application of
prohibitory physician  self-referral  legislation against the Partnership or its
Partners),  the General Partner shall promptly  either,  in its sole discretion,
(i) take the steps outlined in this Article 18.5 to divest the Limited  Partners
of their Partnership Interests,  or (ii) dissolve the Partnership as provided in
Article  24.1(e).  If the General Partner chooses option (i), it shall deliver a
written  notice to all of the Limited  Partners (the "Notice of  Election")  and
purchase such Partnership  Interests for its own account.  The purchase price to
be paid for each  Partnership  Interest  shall be  determined  in the  manner as
provided in Article 18.7 and shall be on the terms and conditions as provided in
Article  18.8.  The transfer of the  Partnership  Interests,  the payment of the
purchase price and the  assumption of the Limited  Partners'  obligations  under
their respective  Guaranties (as provided in Article 18.7) shall be made at such
time as  determined  by the General  Partner to be in the best  interests of the
Partnership and its Limited Partners. Each Limited Partner


                                                       -22-


<PAGE>



hereby makes,  constitutes and appoints the General Partner,  with full power of
substitution,  his true and lawful  attorney-in-fact,  to take such  actions and
execute such  documents on his behalf to effect the transfer of his  Partnership
Interest as provided in this Article 18.5. The foregoing power of attorney shall
not be affected by the subsequent incapacity,  mental incompetence,  dissolution
or bankruptcy of any Limited Partner.

                  18.6  Default  under  Guaranties.  Notwithstanding  any  other
provision in this Article 18 to the contrary,  if any of the events  outlined in
Articles  18.1 or 18.2 or any other  defaulting  event  outlined in the Guaranty
(the  "Defaulting  Events")  should occur with respect to a Limited Partner (the
"Defaulting  Limited Partner"),  and the General Partner determines (in its sole
discretion)  that  such  event may  result in  default  and  acceleration  of an
obligation  secured by the Guaranty unless another  guarantor  acceptable to the
Lender can be substituted in the place of the Defaulting  Limited Partner,  then
the  General  Partner  shall  have the  right to  immediately  take the steps as
outlined in this Article 18.6 to prevent such default.  Upon the General Partner
receiving  notice of a Defaulting  Event as provided above, the General Partner,
in its sole discretion,  shall immediately have the right to either (i) sell the
entire  Partnership  Interest of the Defaulting  Limited  Partner to an investor
approved of by the General Partner, (ii) purchase for its own account the entire
Partnership Interest of the Defaulting Limited Partner, or (iii) sell the entire
Partnership  Interest of the  Defaulting  Limited  Partner to one or more of the
other Limited  Partners.  The Defaulting  Limited  Partner shall sell his or her
Partnership  Interest to the purchaser at the purchase  price  determined in the
manner as provided in Article 18.7 and on the terms and  conditions  as provided
in Article 18.8. The transfer of the  Partnership  Interest,  the payment of the
purchase  price,  and  the  assumption  of  the  Defaulting   Limited  Partner's
obligations  under his or her Guaranty (as provided in Article  18.7),  shall be
made at such time as  determined  by the  General  Partner in order to avoid the
default and acceleration of the obligation secured by the Guaranty. Each Limited
Partner hereby makes,  constitutes and appoints the General  Partner,  with full
power of substitution, his or her true and lawful attorney-in-fact, to take such
actions and execute  such  documents on his or her behalf to effect the transfer
of his or her  Partnership  Interest as provided in this  Article  18.6,  in the
event such Limited Partner becomes a Defaulting Limited Partner.

                  18.7  Purchase  Price.  The purchase  price to be paid for the
Partnership  Interest of any Limited  Partner whose interest is being  purchased
pursuant to the provisions of Articles 18.1, 18.2, 18.3, 18.4, 18.5 or 18.6 (the
"Selling  Limited  Partner")  shall be determined in the manner provided in this
Article 18.7. The purchase price for a Partnership  Interest  purchased pursuant
to the provisions of Article 18.1 shall be an amount equal to the greater of (i)
one and one-half  (1.5) times the aggregate  distributions  made with respect to
such  Partnership  Interest  pursuant to Article  14(a) during the  twelve-month
period  ending on the  Valuation  Date (as defined  below),  or (ii) the Selling
Limited Partner's share of the Partnership's book value determined in the manner
described  below.  The  purchase  price  for a  Partnership  Interest  purchased
pursuant to the provisions of Articles 18.2,  18.3,  18.4, 18.5 or 18.6 shall be
an  amount  equal to the  lesser  of (i) the fair  market  value of the  Selling
Limited  Partner's  Partnership  Interest on the Valuation Date (prorated in the
event that only a portion of his or her Partnership Interest is being purchased)
as  determined  by an  Appraiser  (as  defined  below)  selected  by the General
Partner, or (ii) the Selling Limited Partner's share of the


                                                       -23-


<PAGE>



Partnership's  book value,  if any (prorated in the event that only a portion of
his or her Partnership  Interest is being purchased) as reflected by the Capital
Account of the Selling  Limited  Partner  (unadjusted  for any  appreciation  in
Partnership  assets  and as reduced by  depreciation  deductions  claimed by the
Partnership for tax purposes) as of the Valuation Date (as defined  below).  The
General Partner, in its sole discretion,  may pursue both of the above valuation
methods  and choose  the  lesser  value of the two as  indicated  above,  or may
designate and follow only one of the methods in calculating  the purchase price.
For  purposes  of  this  Article  18.7,  the  term  "Appraiser"  shall  mean  an
independent  appraiser  who  is  qualified  in  appraising  limited  partnership
interests and who has at least five years experience. In determining fair market
value, the Appraiser shall take into consideration any outstanding indebtedness,
liabilities,   liens  and  obligations  of  the  Partnership  and  the  relative
Partnership  Interests and capital accounts of all Partners, as well as applying
any customary discounts for lack of liquidity and control.  Such appraisal shall
be conducted in accordance with professional appraisal standards.  The valuation
of the  Appraiser  shall be  conclusive  and binding upon the  Partnership,  the
purchaser and the Selling  Limited Partner and his or her  representatives.  The
determination  of the Selling  Limited  Partner's  Capital  Account or aggregate
distributable  amount on the Valuation  Date (as defined below) shall be made by
the  Partnership's  internal  accountant (the  "Partnership  Accountant") upon a
review of the  Partnership  books of account,  and a formal  audit is  expressly
waived. The statement of the Partnership  Accountant with respect to the Capital
Account or aggregate  distributable amount of the Selling Limited Partner on the
Valuation  Date  shall be  binding  and  conclusive  upon the  Partnership,  the
purchaser and the Selling  Limited Partner and his or her  representatives.  The
Valuation Date means the last day of the month  immediately  preceding the month
in which occurs:  (i) the death of a Selling Limited  Partner,  in the case of a
purchase by reason of death;  (ii) the  bankruptcy  or  insolvency  of a Selling
Limited  Partner,  in the case of a  purchase  by reason of such  bankruptcy  or
insolvency; (iii) the Notice of Withdrawal or breach of Article 15.3 as provided
in  Article  18.3  in the  case  of a  purchase  by  reason  thereof;  (iv)  the
commencement  of the  Domestic  Proceeding,  in the case of a purchase by reason
thereof;  (v) the Notice of Election as provided in Article 18.5, in the case of
a purchase by reason thereof; or (vi) the notice of Defaulting Event as provided
in Article  18.6,  in the case of a purchase  occurring by reason of one of such
events. Any Limited Partner whose Partnership  Interest is purchased pursuant to
the provisions of Article 18.1, 18.2, 18.3, 18.4, 18.5 or 18.6 shall be entitled
only to the  purchase  price  which  shall be paid at the Closing in cash (or by
certified  or  cashier's  check) and shall not be  entitled  to any  Partnership
distributions  made after the Valuation  Date.  The  Partnership  shall have the
right to deduct  the amount of any  distributions  made to the  Selling  Limited
Partner after the Valuation Date from the purchase  price.  If as of the date of
the  Closing the  Selling  Limited  Partner  still has an  outstanding  personal
obligation under the Guaranty (the "Obligation"), the purchaser shall assume the
portion of the Obligation as is equal to the portion of the Partnership Interest
being purchased,  indemnify the Selling Limited Partner from such portion of the
Obligation,  and take such steps  deemed  necessary  by the  General  Partner to
formally  evidence the assumption of such portion of the  Obligation,  including
without  limitation,  executing  such  documents  and providing  such  financial
information  to the Bank to  evidence  the  assumption  of such  portion  of the
Obligation,  and obtain if possible,  the release of the Selling Limited Partner
from such portion of the Obligation. The transfer of a Partnership Interest of a
Selling  Limited  Partner shall be deemed to occur as of the Valuation  Date and
the Selling Limited Partner shall have no voting


                                                       -24-


<PAGE>



or other rights as a Limited Partner after such date. Notwithstanding the above,
the  Partnership  shall not be  obligated  to assume  any  outstanding  personal
obligation of a Selling Limited Partner.

                  18.8     Closing.
                           -------

                  18.8.1  Closing  of  Purchase  and Sale.  The  Closing  of any
         purchase and sale of a Partnership  Interest  pursuant to Article 18.1,
         18.2,  18.3,  18.4 or 18.5 of this  Agreement  shall  take place at the
         principal office of the Partnership,  or such other place designated by
         the General Partner, on the date determined as follows (the "Closing"):

                  (a) In the case of a purchase and sale  occurring by reason of
         the death of a Limited  Partner as  provided  in  Article  18.1 of this
         Agreement,  the Closing  shall be held on the thirtieth day (or if such
         thirtieth  day is not a business  day, the next  business day following
         the thirtieth day) next following the last to occur of:

                    (i) Qualification of the executor or personal  administrator
               of the deceased Limited Partner's estate;

                    (ii) The date on which any  necessary  determination  of the
               purchase  price of the  Partnership  Interest to be purchased has
               been made; or

                    (iii) The date that  coincides  with the close of the Option
               Period.

                  (b) In the case of a purchase and sale  occurring by reason of
         the  occurrence of one of the events  described in Article 18.2,  18.3,
         18.4 or  18.5  of this  Agreement,  the  Closing  shall  be held on the
         thirtieth day (or if such thirtieth day is not a business day, the next
         business day following the thirtieth  day) next  following the later to
         occur of:

                    (i) The date on which  any  necessary  determination  of the
               purchase  price of the  Partnership  Interest to be purchased has
               been made; or

                    (ii) The date that  coincides  with the close of the  Option
               Period.

         At the Closing,  although not  necessary  to effect the  transfer,  the
         Selling Limited Partner shall  concurrently  with tender and receipt of
         the applicable  purchase price,  deliver to the purchaser duly executed
         instruments of transfer and  assignment,  assigning good and marketable
         title to the portion or portions of the Selling Limited


                                                       -25-


<PAGE>



         Partner's entire  Partnership  Interest thus purchased,  free and clear
         from any liens or encumbrances or rights of others therein. The parties
         acknowledge  that occurrence of any of the triggering  events described
         in Article 18.1, 18.2, 18.3, 18.4, 18.5 or 18.6 and compliance with all
         the Articles of this  Agreement,  except the  execution of the transfer
         documents  by the Selling  Limited  Partner as  provided  above in this
         Article 18.8.1,  are sufficient to effect the complete  transfer of the
         Selling Limited Partner's  Partnership Interest and the Selling Limited
         Partner shall be deemed to consent to admission of the  transferee as a
         substitute Limited Partner.  Notwithstanding the date of the Closing or
         whether a Closing is  successfully  held, the transfer of a Partnership
         Interest of a Selling  Limited  Partner  shall be deemed to occur as of
         the Valuation Date as defined in Article 18.7.  The deemed  transfer is
         effective  regardless of whether the Selling Limited  Partner  performs
         the duties set forth in this Article 18.8.1.

                  18.8.2  Terms and  Conditions  of  Purchase.  The  Partnership
         Interest of a Limited  Partner shall not be  transferred to any Partner
         unless the  requirements  of Articles 17.2 and 17.4 (b) through (f) are
         satisfied  with  respect to it. The  purchaser  shall be liable for all
         obligations  and  liabilities   connected  with  that  portion  of  the
         Partnership  Interest  transferred  to it  unless  otherwise  agreed in
         writing.

                  19.      SALE, ASSIGNMENT OR OTHER TRANSFER OF THE GENERAL
                           -------------------------------------------------
                           PARTNER'S INTEREST.
                           ------------------

                  19.1  The   General   Partner   may  not   mortgage,   pledge,
hypothecate,  transfer,  sell, assign or otherwise dispose of all or any part of
its interest in the  Partnership,  whether  voluntarily,  by operation of law or
otherwise (the foregoing  actions being  hereafter  collectively  referred to as
"Transfers" or singularly as a "Transfer") except as permitted by this Article.

                  19.2 If the  General  Partner  makes a Transfer  (other than a
mortgage,  pledge or  hypothecation)  of its  general  partner  interest  in the
Partnership pursuant to this Article, it shall be liable for all obligations and
liabilities  incurred  by it as the  general  partner of the  Partnership  on or
before  the  effective  date of such  Transfer,  but shall not be liable for any
obligations or liabilities of the  Partnership  arising after the effective date
of the Transfer.

                    19.3 No Transfer by the General  Partner  shall be permitted
               unless:

                  (a) Counsel for the Partnership shall have rendered an opinion
         that none of the actions  taken in  connection  with such Transfer will
         cause the Partnership to be classified  other than as a partnership for
         federal   income  tax  purposes  or  will  cause  the   termination  or
         dissolution of the Partnership under state law; and

                    (b) Such  documents or  instruments,  in form and  substance
               satisfactory  to  counsel  for the  Partnership,  shall have been
               executed and delivered as may be


                                                       -26-


<PAGE>



                    required in the opinion of counsel  for the  Partnership  to
               effect fully any such Transfer.

                  Notwithstanding the foregoing provisions of this Article 19.3,
the General  Partner may pledge its  interest  in the  Partnership  to any bank,
insurance   company  or  other  financial   institution  to  secure  payment  of
indebtedness.

                  20.      TERMINATION OF THE SERVICES OF THE GENERAL PARTNER.
                           --------------------------------------------------

                  If the General Partner shall be finally adjudged by a court of
competent  jurisdiction to be liable to the Limited  Partners or the Partnership
for any act of gross negligence or willful  misconduct in the performance of its
duties under the terms of this Agreement, the General Partner may be removed and
another  substituted  with the  consent  of all of the  Limited  Partners.  Such
consent  shall be evidenced  by a  certificate  of removal  signed by all of the
Limited Partners. In the event of removal, the new general partner shall succeed
to all of the powers, privileges and obligations of the General Partner, and the
General  Partner's  interest in the  Partnership  shall become that of a Limited
Partner,  and the General Partner shall maintain its same Percentage Interest in
the Partnership  notwithstanding  anything contained in the Act to the contrary.
In addition,  in the event of removal,  the new general  partner  shall take all
steps  necessary  and  appropriate  to prepare  and record an  amendment  to the
Certificate of Limited Partnership to reflect the removal of the General Partner
and the admission of such new general partner.

                  21.      MANAGEMENT AND OPERATION OF BUSINESS.
                           ------------------------------------

                  21.1 All  decisions  with  respect  to the  management  of the
business and affairs of the Partnership shall be made by the General Partner.

                  21.2 The General  Partner shall be under no duty to devote all
of its time to the business of the Partnership,  but shall devote only such time
as it deems  necessary  to conduct the  Partnership  business and to operate and
manage the Partnership in an efficient manner.

                  21.3 The  General  Partner may charge to the  Partnership  all
ordinary and necessary costs and expenses, direct and indirect,  attributable to
the activities,  conduct and management of the business of the Partnership.  The
costs and expenses to be borne by the  Partnership  shall  include,  but are not
limited to, all  expenditures  incurred in acquiring and financing the Equipment
or other Partnership property, legal and accounting fees and expenses,  salaries
of employees of the Partnership,  consulting and quality  assurance fees paid to
independent contractors, insurance premiums and interest.

                  21.4 In addition to, and not in limitation  of, any rights and
powers  covenanted by law or other  provisions of this Agreement,  and except as
limited,  restricted or prohibited by the express  provisions of this Agreement,
the General Partner shall have and may exercise on behalf of the Partnership all
powers and rights necessary, proper, convenient or advisable to effectuate and


                                                       -27-


<PAGE>



     carry out the purposes,  business and objectives of the  Partnership.  Such
powers shall include, without limitation, the following:

                    (a) To conduct the  Offering  and any  Dilution  Offering on
               behalf of the Partnership;

                  (b) To  acquire on behalf of the  Partnership  (i) one or more
         fixed  base  or  transportable   lithotripsy  systems,   including  the
         Lithotripsy  System,  (ii) any other assets related to the provision of
         lithotripsy  services,  or (iii) any other  assets or  equipment  or an
         interest  in  another  entity  consistent  with  the  purposes  of  the
         Partnership  as provided in Article 4  (collectively,  the  "Additional
         Assets"),  at such times and at such price and upon such terms,  as the
         General Partner deems to be in the best interest of the Partnership;

                  (c) To purchase,  hold, manage,  lease, license and dispose of
         Partnership assets, including the purchase,  exchange, trade or sale of
         the Partnership's assets at such price, or amount, for cash, securities
         or other property and upon such terms,  as the General Partner deems to
         be in the best interest of the Partnership;  provided,  that should the
         Partnership  assets be  exchanged  or traded  for  securities  or other
         property (the  "Replacement  Property") the General  Partner shall have
         the same  powers  with  regard to the  Replacement  Property as it does
         towards the traded property;

                    (d) To  exercise  the option of the  General  Partner or the
               Partnership to purchase a Limited Partner's  Partnership Interest
               pursuant to Article 18;

                    (e) To determine the travel itinerary and site locations for
               the Lithotripsy System or other Partnership technology;

                  (f) To borrow money for any Partnership purpose (including the
         acquisition  of the  Additional  Assets)  and,  if security is required
         therefor, to subject to any security device any portion of the property
         for the  Partnership,  to obtain  replacements  of any  other  security
         device, to prepay, in whole or in part,  refinance,  increase,  modify,
         consolidate or extend any encumbrance or other security device;

                  (g) To deposit,  withdraw,  invest, pay, retain (including the
         establishment  of reserves in order to acquire the  Additional  Assets)
         and distribute the  Partnership's  funds in any manner  consistent with
         the provisions of this Agreement;

                  (h)      To institute and defend actions at law or in equity;

                    (i) To enter into and carry out contracts and agreements and
               any or all documents and  instruments  and to do any and all such
               other things as may be in


                                                       -28-


<PAGE>



                    furtherance   of   Partnership   purposes  or  necessary  or
               appropriate to the conduct of the Partnership activities;

                    (j)  To  execute,   acknowledge  and  deliver  any  and  all
               instruments which may be deemed necessary or convenient to effect
               the foregoing;

                  (k) To engage or retain one or more persons to perform acts or
         provide  materials  as  may be  required  by  the  Partnership,  at the
         Partnership's  expense,  and to compensate  such person or persons at a
         rate to be set by the General  Partner,  provided that the compensation
         is at the then  prevailing  rate for the type of services and materials
         provided,  or both.  Any person,  whether a Partner,  an Affiliate of a
         Partner or otherwise, including without limitation the General Partner,
         may be employed or engaged by the  Partnership  to render  services and
         provide materials,  including, but not limited to, management services,
         professional   services,   accounting   services,   quality  assessment
         services, legal services,  marketing services,  maintenance services or
         provide materials; and if such person is a Partner or an Affiliate of a
         Partner, (s)he shall be entitled to, and shall be paid compensation for
         said services or materials,  anything in this Agreement to the contrary
         notwithstanding, provided that the compensation to be received for such
         services  or  materials  is  competitive  in price and terms  with then
         prevailing rate for the type of services and/or materials provided. The
         Partnership,  pursuant  to the terms of a  Management  Agreement,  will
         contract with Sun Medical Technologies,  Inc., a California corporation
         ("Sun")  with  respect  to  the  supervision  and  coordination  of the
         management  and  administration  of the  day-to-day  operations  of the
         Partnership's  business  for  a  monthly  fee  equal  to  7.5%  of  net
         Partnership  Cash Flow per month.  All costs  incurred by Sun under the
         Management  Agreement  shall be paid or reimbursed  by the  Partnership
         directly.  The Partnership may also contract with healthcare facilities
         and/or qualified  physicians desiring to use its Lithotripsy System for
         the treatment of patients.  Owning an interest in the Partnership shall
         not be a condition to using the Lithotripsy System. The General Partner
         and its Affiliates (including Sun) may engage in or possess an interest
         in other business ventures of any nature and description  independently
         or with  others,  including,  but not  limited to, the  operation  of a
         fixed-base  or mobile  lithotripsy  unit,  whether or not such business
         ventures are in direct or indirect  competition  with the  Partnership,
         and neither the  Partnership  nor the Partners  shall have any right by
         virtue of this Agreement in and to said independent  ventures or to the
         income or profits derived therefrom.

                  21.5  In  addition  to  other  acts  expressly  prohibited  or
restricted  by this  Agreement  or by law,  the  General  Partner  shall have no
authority to act on behalf of the Partnership in:

                    (a) Doing any act in  contravention of this Agreement or the
               Partnership's Certificate of Limited Partnership;



                                                       -29-


<PAGE>



                    (b) Doing any act which would make it impossible to carry on
               the ordinary business of the Partnership;

                    (c)   Possessing   or  in  any  manner   dealing   with  the
               Partnership's property or assigning the rights of the Partnership
               in  the   Partnership's   property  for  other  than  Partnership
               purposes;

                    (d)  Admitting  a person as a Limited  Partner  or a General
               Partner except as provided in this Agreement; or

                  (e)  Performing  any act (other  than an act  required by this
         Agreement  or any act  taken  in good  faith  reliance  upon  counsel's
         opinion)  which  would,  at the time  such act  occurred,  subject  any
         Limited Partner to liability as a general partner in any jurisdiction.

                  22.      RESERVES.
                           --------

                  The  General  Partner  may cause the  Partnership  to create a
reserve account to be used exclusively for repairs and acquisition of Additional
Assets and for any other valid Partnership  purpose.  The General Partner shall,
in its sole discretion, determine the amount of payments to such reserve.

                  23.      INDEMNIFICATION AND EXCULPATION OF THE GENERAL

                           PARTNER.

                  23.1 The General  Partner is accountable to the Partnership as
a fiduciary and consequently  must exercise good faith and integrity in handling
Partnership  affairs.  The  General  Partner  and its  Affiliates  shall have no
liability to the  Partnership  which arises out of any action or inaction of the
General Partner or its Affiliates if the General  Partner or its Affiliates,  in
good faith,  determined  that such course of conduct was in the best interest of
the Partnership and such course of conduct did not constitute  gross  negligence
or willful  misconduct  of the General  Partner or its  Affiliates.  The General
Partner and its Affiliates  shall be indemnified by the Partnership  against any
losses, judgments,  liabilities,  expenses and amounts paid in settlement of any
claims sustained by them in connection with the  Partnership,  provided that the
same were not the result of gross  negligence or willful  misconduct on the part
of the General Partner or its Affiliates.

                  23.2 The General Partner shall not be liable for the return of
the Capital Contributions of the Limited Partners, and upon dissolution, Limited
Partners shall look solely to the assets of the Partnership.


                                                       -30-


<PAGE>



                  24.      DISSOLUTION OF THE PARTNERSHIP.
                           ------------------------------

                    24.1 The  Partnership  shall be dissolved and terminated and
               its  business  wound  up upon  the  occurrence  of any one of the
               following events:

                  (a)      The expiration of its term on December 31, 2049;

                  (b) The  filing  by, on  behalf  of, or  against  the  General
         Partner of any  petition or  pleading,  voluntary  or  involuntary,  to
         declare the General  Partner  bankrupt under any bankruptcy law or act,
         or the  commencement  in any  court  of any  proceeding,  voluntary  or
         involuntary,  to declare the General Partner insolvent or unable to pay
         its debts, or the appointment by any court or supervisory  authority of
         a  receiver,  trustee or other  custodian  of the  property,  assets or
         business of the General  Partner or the  assignment by it of all or any
         part of its  property or assets for the benefit of  creditors,  if said
         action,  proceeding  or  appointment  is  not  dismissed,   vacated  or
         otherwise terminated within ninety (90) days of its commencement;

                    (c)  The  determination  of the  General  Partner  that  the
               Partnership should be dissolved;

                  (d) The occurrence of an event described in a plan approved by
         the General Partner and a Majority in Interest of the Limited  Partners
         pursuant  to  Article  17.7   resulting  in  the   dissolution  of  the
         Partnership;

                    (e) The  election  of the General  Partner to  dissolve  the
               Partnership  following the  occurrence  of an event  described in
               Article 18.5;

                  (f) Except as otherwise  provided in any plan  approved by the
         General  Partner and a Majority  in  Interest  of the Limited  Partners
         pursuant to Article 17.7,  the sale,  exchange or other  disposition of
         all or  substantially  all of the property of the  Partnership  without
         making provision for the replacement thereof; and

                  (g)   The   dissolution,   retirement,   resignation,   death,
         disability  or legal  incapacity  of a general  partner,  and any other
         event  resulting in the  dissolution or termination of the  Partnership
         under the laws of the State of  California;  provided,  that the events
         described  in  Sections  15681(c)  and  (d) of the  Act or any  similar
         provisions of any successor  statute,  shall not work a dissolution  of
         the Partnership except as expressly provided in (b) above.

                  24.2  Notwithstanding  the  provisions  of Article  24.1,  the
Partnership   shall  not  be  dissolved  and  terminated  upon  the  retirement,
resignation,  bankruptcy,  assignment for the benefit of creditors, dissolution,
death,  disability or legal  incapacity of a general  partner,  and its business
shall continue  pursuant to the terms and conditions of this  Agreement,  if any
general partner or



                                                       -31-


<PAGE>



general  partners  remain  following  such event;  provided that such  remaining
general  partner or  general  partners  are hereby  obligated  to  continue  the
business of the Partnership.  If no general partner remains after the occurrence
of such event,  the business of the Partnership  shall continue  pursuant to the
terms and  conditions of this  Agreement,  if, within ninety (90) days after the
occurrence of such event,  a Majority in Interest of the Limited  Partners agree
in writing to continue the business of the  Partnership,  and, if necessary,  to
the  appointment  of one or more  persons or entities to be  substituted  as the
general  partner.  In the event the Limited  Partners agree as provided above to
continue the  business of the  Partnership,  the new general  partner or general
partners shall succeed to all of the powers,  privileges and  obligations of the
General Partner,  and the General  Partner's  interest in the Partnership  shall
become a  Limited  Partner's  interest  hereunder.  Furthermore,  in the event a
remaining general partner or the Limited Partners,  as the case may be, agree to
continue the  business of the  Partnership  as provided  herein,  the  remaining
general partner or the newly appointed general partner or general  partners,  as
the case may be, shall take all steps  necessary and  appropriate to prepare and
record an amendment to the  Certificate  of Limited  Partnership  to reflect the
continuation  of the  business of the  Partnership  and the  admission  of a new
general partner or general partners, if any.

                  25.      DISTRIBUTION UPON DISSOLUTION.
                           -----------------------------

                  Upon the dissolution and termination of the  Partnership,  the
General Partner or, if there is none, a representative  of the Limited Partners,
shall  cause  the  cancellation  of the  Partnership's  Certificate  of  Limited
Partnership,  shall liquidate the assets of the Partnership, and shall apply and
distribute the proceeds of such liquidation in the following order of priority:

                    (a) First,  to the payment of the debts and  liabilities  of
               the Partnership, and the expenses of liquidation;

                  (b) Second,  to the creation of any reserves which the General
         Partner  (or such  representatives  of the Limited  Partners)  may deem
         reasonably  necessary  for the payment of any  contingent or unforeseen
         liabilities or obligations of the Partnership or of the General Partner
         arising out of or in connection  with the business and operation of the
         Partnership; and

                  (c) Third,  the balance,  if any,  shall be distributed to the
         Partners in accordance  with the  Partners'  positive  Capital  Account
         balances  after such  Capital  Accounts  are  adjusted  as  provided by
         Article 13, and any other  adjustments  required by the Final  Treasury
         Regulations  under Section 704(b) of the Code. Any general partner with
         a negative  Capital Account  following the  distribution of liquidation
         proceeds or the  liquidation  of its interest  must  contribute  to the
         Partnership  an amount  equal to such  negative  Capital  Account on or
         before the end of the Partnership's  taxable year (or, if later, within
         ninety days after the date of liquidation).  Any capital so contributed
         shall be (i) distributed to those Partners with


                                                       -32-


<PAGE>



         positive  Capital  Accounts until such Capital  Accounts are reduced to
         zero, and/or (ii) used to discharge recourse liabilities.

                  26.      BOOKS OF ACCOUNT, RECORDS AND REPORTS.
                           -------------------------------------

                  26.1 Proper and complete records and books of account shall be
kept by the General  Partner in which shall be entered fully and  accurately all
transactions  and such other matters relating to the  Partnership's  business as
are usually  entered  into  records and books of account  maintained  by persons
engaged  in  businesses  of a like  character.  The  books  and  records  of the
Partnership  shall be prepared  according to the accounting method determined by
the General Partner.  The Partnership's  fiscal year shall be the calendar year.
The books and  records  shall at all times be  maintained  at the  Partnership's
Records Office and shall be open to the reasonable inspection and examination of
the Partners or their duly authorized representatives during reasonable business
hours.

                  26.2 Within  ninety (90) days after the end of each Year,  the
General  Partner shall send to each person who was a Limited Partner at any time
during such year such tax information,  including,  without limitation,  federal
tax Schedule K-1, as shall be reasonably  necessary for the  preparation by such
person of his or her federal  income tax return.  The General  Partner will also
make  available to the Limited  Partners any other  information  required by the
Act.

                  26.3 The General  Partner shall maintain at the  Partnership's
Records  Office  copies of the  Partnership's  original  Certificate  of Limited
Partnership   and  any  certificate  of  amendment,   restated   certificate  or
certificate of cancellation with respect thereto and such other documents as the
Act shall require.  The General Partner will furnish to any Limited Partner upon
request or as  otherwise  required by law a copy of the  Partnership's  original
Certificate of Limited  Partnership and any  certificate of amendment,  restated
certificate, or certificate of cancellation, if any.

                  26.4 The General Partner shall, in its sole  discretion,  make
for the  Partnership  any and all  elections  for  federal,  state and local tax
purposes including, without limitation, any election, if permitted by applicable
law, to adjust the basis of the Partnership's property pursuant to Code Sections
754,  734(b) and  743(b),  or  comparable  provisions  of state or local law, in
connection  with  transfers  of  interests in the  Partnership  and  Partnership
Distributions.

                  26.5 The  General  Partner is  designated  as the Tax  Matters
Partner  (as  defined  in  Section  6231 of the Code) and to act in any  similar
capacity  under  state or local law,  and is  authorized  (at the  Partnership's
expense):   (i)  to  represent  the   Partnership  and  Partners  before  taxing
authorities  or courts of competent  jurisdiction  in tax matters  affecting the
Partnership  or  Partners  in their  capacity  as  Partners;  (ii) to extend the
statute of limitations for assessment of tax deficiencies  against Partners with
respect to adjustments to the Partnership's federal, state or local tax returns;
(iii) to execute any agreements or other documents relating to or affecting such
tax matters, including agreements or other documents that bind the Partners with
respect to such tax matters or  otherwise  affect the rights of the  Partnership
and Partners; and (iv) to expend Partnership funds for professional


                                                       -33-


<PAGE>



services and costs associated  therewith.  The General Partner is authorized and
required  to  notify  the  federal,  state  or  local  tax  authorities  of  the
appointment  of a Tax  Matters  Partner  in  the  manner  provided  in  Treasury
Regulations  Section  301.6231(a)(7)-1,  as modified  from time to time.  In its
capacity  as  Tax  Matters  Partner,  the  General  Partner  shall  oversee  the
Partnership's  tax affairs in the manner which, in its best judgment,  is in the
interests of the Partners.

                  27.      NOTICES.
                           -------

                  All notices under this Agreement shall be in writing and shall
be deemed to have been given when delivered  personally,  or mailed by certified
or registered mail, postage prepaid,  return receipt  requested.  Notices to the
General  Partner  shall be  delivered  at, or mailed to, its  principal  office.
Notices to the  Partnership  shall be delivered  at, or mailed to, its principal
office with a copy to each of its business offices.  Notice to a Limited Partner
shall be  delivered  to such  Limited  Partner,  or mailed  to the last  address
furnished  by him for such  purposes to the General  Partner.  Limited  Partners
shall give  notice of a change of address to the  General  Partner in the manner
provided in this Article.

                  28.      AMENDMENTS.
                           ----------

                  Subject to the  provisions  of Article 28, this  Agreement  is
subject to  amendment  only by  written  consent of the  General  Partner  and a
Majority in Interest of the Limited Partners;  provided, however, the consent of
the Limited Partners shall not be required if such amendments are ministerial in
nature and do not contravene the provisions of Article 29.  Further,  no Limited
Partner  consent shall be required to amend  Schedule A to reflect the admission
of  Partners  as  contemplated  by the  Offering,  any  Dilution  Offering or as
otherwise herein permitted.

                  29.      LIMITATIONS ON AMENDMENTS.
                           -------------------------

                  Notwithstanding  the provisions of Article 28, no amendment to
this Agreement shall:

                  (a)  Enlarge  the   obligations  of  any  Partner  under  this
         Agreement  or convert the  interest in the  Partnership  of any Limited
         Partner  into the  interest of a general  partner or modify the limited
         liability of any Limited Partner, without the consent of such Partner;

                  (b) Amend the  provisions  of Article 13, 14, 16 or 25 without
         the  approval of the General  Partner and a Majority in Interest of the
         Limited Partners;  provided,  however,  that the General Partner may at
         any time  amend  such  Articles  without  the  consent  of the  Limited
         Partners in order to permit the Partnership allocations to be sustained
         for federal  income tax  purposes,  but only if such  amendments do not
         materially  affect  adversely the rights and obligations of the Limited
         Partners, in which case such amendments may only be made as provided in
         this Article 29(b); or


                                                       -34-


<PAGE>



                    (c)  Amend  this  Article  29  without  the  consent  of all
               Partners.

                  30.      MEETINGS, CONSENTS AND VOTING.
                           -----------------------------

                  30.1 A meeting of the  Partnership to consider any matter with
respect to which the  Partners  may vote as set forth in this  Agreement  may be
called  by the  General  Partner  or by  Limited  Partners  who hold  more  than
twenty-five  percent (25%) of the aggregate interests in the Partnership held by
all the Limited Partners.  Upon receipt of a notice requesting a meeting by such
Partner or Partners and stating the purpose of the meeting,  the General Partner
shall, within ten (10) days thereafter, give notice to the Partners of a meeting
of the  Partnership to be held at a time and place  generally  convenient to the
Limited  Partners on a date not earlier than fifteen (15) days after  receipt by
the  General  Partner of the  notice  requesting  a  meeting.  The notice of the
meeting shall set forth the time, date, location and purpose of the meeting.

                    30.2 Any consent of a Partner required by this Agreement may
               be given as follows:

                    (a) By a written consent given by the consenting Partner and
               received by the  General  Partner at or prior to the doing of the
               act or thing for which the consent is solicited, or

                  (b) By the affirmative  vote by the consenting  Partner to the
         doing of the act or thing for which the  consent  is  solicited  at any
         meeting  called  pursuant to this Article to consider the doing of such
         act or thing.

                  30.3 When exercising voting rights expressly granted under the
Articles of this  Agreement,  each Partner shall have that number of votes as is
equal to the  Percentage  Interest  of such  Partner  at the  time of the  vote,
multiplied by 100.

                  31.      SUBMISSIONS TO THE LIMITED PARTNERS.
                           -----------------------------------

                  The General Partner shall give the Limited  Partners notice of
any proposal or other matter  required by any provision of this  Agreement or by
law to be submitted for consideration and approval of the Limited Partners. Such
notice shall include any  information  required by the relevant  provision or by
law.

                  32.      ADDITIONAL DOCUMENTS.
                           --------------------

                  Each  party  hereto  agrees to  execute  and  acknowledge  all
documents and writings which the General Partner may deem necessary or expedient
in the creation of this Partnership and the achievement of its purpose.


                                                       -35-


<PAGE>



                  33.      SURVIVAL OF RIGHTS.
                           ------------------

                  Except as herein  otherwise  provided  to the  contrary,  this
Agreement  shall be binding upon and inure to the benefit of the parties hereto,
their successor and assigns.

                  34.      INTERPRETATION AND GOVERNING LAW.
                           --------------------------------

                  When the  context  in which  words are used in this  Agreement
indicates  that such is the intent,  words in the singular  number shall include
the plural and vise versa; in addition,  the masculine  gender shall include the
feminine and neuter  counterparts.  The Article headings or titles and the table
of  contents  shall not define,  limit,  extend or  interpret  the scope of this
Agreement  or any  particular  Article.  This  Agreement  shall be governed  and
construed in accordance with the laws of the State of California  without giving
effect to the conflicts of laws provisions thereof.

                  35.      SEVERABILITY.
                           ------------

                  If any provision,  sentence,  phrase or word of this Agreement
or the application  thereof to any person or circumstance shall be held invalid,
the remainder of this Agreement, or the application of such provision, sentence,
phrase, or word to persons or circumstances,  other than those as to which it is
held invalid, shall not be affected thereby.

                  36.      AGREEMENT IN COUNTERPARTS.
                           -------------------------

                  This Agreement may be executed in several  counterparts,  each
of which shall be deemed an original,  but all of which shall constitute one and
the same  instrument.  In  addition,  this  Agreement  may contain more than one
counterpart  of the  signature  page and this  Agreement  may be executed by the
affixing of the  signatures  of each of the Partners to one of such  counterpart
signature  pages;  all of such signature  pages shall be read as though one, and
they  shall have the same  force and  effect as though  all of the  signers  had
signed a single signature page.

                  37.      THIRD PARTIES.
                           -------------

                  The agreements, covenants and representations contained herein
are for the benefit of the parties  hereto  inter se and are not for the benefit
of any  third  parties  including,  without  limitation,  any  creditors  of the
Partnership.

                  38.      POWER OF ATTORNEY.
                           -----------------

                  Each Limited  Partner hereby makes,  constitutes  and appoints
Stan Johnson and Cheryl  Williams,  severally,  with full power of substitution,
his or her true and lawful  attorneys-in- fact, for him or her and in his or her
name,  place  and  stead  and  for  his or her  use  and  benefit  to  sign  and
acknowledge,  file and record,  any amendments hereto among the Partners for the
further purpose of executing and filing on behalf of each Limited  Partner,  any
and all certificates of limited


                                                       -36-


<PAGE>



partnership or other  documents  necessary to constitute  the  Partnership or to
effect the  continuation  of the  Partnership,  the admission or withdrawal of a
general partner or a limited partner,  the qualification of the Partnership in a
foreign  jurisdiction  (or  amendment to such  qualification),  the admission of
substitute   Limited   Partners  or  the   dissolution  or  termination  of  the
Partnership, provided such continuation,  admission, withdrawal,  qualification,
or  dissolution  and  termination  are in  accordance  with  the  terms  of this
Agreement.

                  The foregoing power of attorney is a special power of attorney
coupled with an interest,  is  irrevocable  and shall  survive the death,  legal
incapacity,  dissolution  or  bankruptcy  of  each  Limited  Partner.  It may be
exercised by any one of said  attorneys  by listing all of the Limited  Partners
executing any instrument over the signature of the  attorney-in-fact  acting for
all of them.  The power of attorney  shall survive the delivery of an assignment
by a Limited  Partner of the whole or any  portion of his or her Unit.  In those
cases in which the assignee of, or the successor to, a Limited  Partner owning a
Unit has been  approved by the Partners for  admission to the  Partnership  as a
substitute  Limited  Partner,  the power of attorney  shall survive for the sole
purpose of enabling  the General  Partner to execute,  acknowledge  and file any
instrument necessary to effect such substitution.

                  This power of attorney shall not be affected by the subsequent
bankruptcy,  dissolution,  incapacity  or  mental  incompetence  of any  Limited
Partner.

                  39.      ARBITRATION.
                           -----------

                  Any  dispute  arising  out  of  or  in  connection  with  this
Agreement or the breach thereof shall be decided by arbitration in Austin, Texas
in  accordance  with  the then  effective  commercial  arbitration  rules of the
American  Arbitration  Association,  and judgment  thereof may be entered in any
court having jurisdiction thereof.

                  40.      CREDITORS.
                           ---------

                  None of the  provisions  of this  Agreement  shall  be for the
benefit of or enforceable by any creditors of the Partnership.

                                             [signature page follows]



                                                       -37-


<PAGE>




                  IN WITNESS  WHEREOF,  the parties have executed this Agreement
of Limited Partnership as of the day and year first above written.

                                        GENERAL PARTNER:

                                     MOBILE KIDNEY STONE CENTERS OF

                                     CALIFORNIA, LTD. I, a California limited
                                       partnership

                           By:      Sun Medical Technologies, Inc., a California
                                      corporation and its sole general partner



                                    By:  /s/ Stan Johnson
                                    ---------------------
                                            Stan Johnson
                                            President

ATTEST:

/s/ James D. Clark                                    [CORPORATE SEAL]
- -----------------------
Secretary

                                          INITIAL LIMITED PARTNER:
                                         -----------------------

                                         /s/ Stan Johnson
                                         ----------------
                                         Stan Johnson


                                                       -38-


<PAGE>




STATE OF North Carolina

COUNTY OF Cumberland

                  On this  23  day of August,  1999,  before  me, the
undersigned  Notary Public in and for the County of Cumberland in the State
of  North Carolina,  personally came Stan Johnson, who, being by me
duly sworn,  said that he is President of Sun Medical  Technologies,  Inc.,  the
sole general  partner of Mobile Kidney Stone Centers of California,  Ltd. I, the
sole general  partner of Mobile Kidney Stone Centers of  California  III,  L.P.,
that the seal affixed to the  foregoing  instrument  in writing is the corporate
seal of the corporation,  and that said writing was signed, sworn to, and sealed
by him in behalf of said  corporation by its authority duly given.  And the said
Stan  Johnson,  further  certified  that the facts set forth in said writing are
true and correct,  and  acknowledged  said  instrument to be the act and deed of
said corporation.

                  WITNESS my hand and notarial seal.

                                    Notary Public

My commission expires:

May 1, 2004

STATE OF North Carolina

COUNTY OF Cumberland


                  I, Debra J. Scott, a notary public in and for
the State and  County  set forth  above,  do hereby  certify  that Stan  Johnson
personally  appeared  before  me  this  23  day of  August,  1999  and
acknowledged and swore to the due execution of the foregoing Limited Partnership
Agreement in his capacity as the initial limited partner.

                                    /s/ Debra J. Scott
                                    ------------------
                                    Notary Public

My commission expires:

May 1, 2004





                                                       -39-


<PAGE>



                           COUNTERPART SIGNATURE PAGE

                  By signing this  Counterpart  Signature  Page, the undersigned
acknowledges  his or  her  acceptance  of  that  certain  Agreement  of  Limited
Partnership  of Mobile Kidney Stone Centers of California  III, L.P., and his or
her intention to be legally bound thereby.

                  Dated this _________ day of ___________________, 1999.



                                   Signature

                                   Printed Name

STATE OF _______________                    )
                                            )
COUNTY OF _____________                     )


                  BEFORE ME, the undersigned  Notary Public in and for the State
and County set forth  above,  on the  _______ day of  __________________,  1999,
personally appeared ___________________________________,  and, being by me first
duly sworn,  stated that (s)he signed this  Counterpart  Signature  Page for the
purpose set forth above and that the statements contained therein are true.

                           Signature of Notary Public

                           Printed Name of Notary

My Commission Expires:

- ---------------------------
[SEAL]

                                                       -40-


<PAGE>



                                   SCHEDULE A

                        Schedule of Partnership Interests

               MOBILE KIDNEY STONE CENTERS OF CALIFORNIA III, L.P.
               ---------------------------------------------------

           CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND PERCENTAGE

                                    INTERESTS

                                   Cash                              Percentage

General Partner                  Contribution      Guaranty(1)        Interest
- ---------------                 ------------        --------         -----------

Mobile Kidney Stone Centers      $  97,667.00    $194,850.00                40%
of California, Ltd. I
1301 Capital of Texas Highway
Suite C-300
Austin, Texas  78746

Limited Partners

N. Erik Albert, M.D.            $    5,000.00    $  9,742.50                 2%
Gene R. Conley, M.D.                 7,500.00      14,613.75                 3%
Rajendra H. Dwivedi, M.D.           12,500.00      24,356.25                 5%
Barton Gershbein, M.D.              12,500.00      24,356.25                 5%
Tu-Hi Hong, M.D.                    12,500.00      24,356.25                 5%
William W. Kirby, M.D.              12,500.00      24,356.25                 5%
Gregory M. Lomas, M.D.               2,500.00       4,871.25                 1%
Mobile Kidney Stone Centers         31,500.00      68,197.50                14%
     of California, Ltd. I
Robert J. Reiner, M.D.              12,500.00      24,356.25                 5%
Alfonso Richards, M.D.              12,500.00      24,356.25                 5%
Mark A. Silvert, M.D.               12,500.00      24,356.25                 5%
Alan K. Wong, M.D.                  12,500.00      24,356.25                 5%

TOTAL:                            $244,167.00    $487,125.00               100%
                                  ===========    ===========               ====

(1)      Represents the principal portion of each Partner's guaranty obligation,
         as each  Partner's  obligation  under the  Guaranty  includes  not only
         principal,  but also (as provided in the  Guaranty)  accrued and unpaid
         interest,  late payment penalties and all costs incurred by the Bank in
         collecting any defaulted obligations.  The principal amount of the loan
         is up to $487,125.  The General  Partner will guarantee 40% of the Loan
         (up to a $194,850  principal  guaranty) as provided in the  Memorandum.
         The Limited Partners will individually  guarantee 1% of the loan (up to
         a $4,871.25  principal guaranty) for each unit purchased as provided in
         the Memorandum.


                                                       -41-



                        AMENDMENT TO FIRST AMENDED AND
                    RESTATED AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                         OHIO MOBILE LITHOTRIPTER, LTD.

     THIS  AMENDMENT,  effective  January 1, 2000,  is entered into by and among
Ohio Litho,  Inc., a Delaware  corporation,  the General  Partner of Ohio Mobile
Lithotripter,  Ltd., a Texas limited  partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.

                                    RECITALS:
                                    --------

                  A. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the  "Partners,"  entered into that  certain  First
Amended and Restated  Agreement of Limited  Partnership dated August 1, 1991, as
heretofore  amended  (the  "Agreement").  Capitalized  terms used herein and not
otherwise defined shall have the meanings given them in the Agreement.

     B. The Partners desire to amend the Agreement to substitute the Partnership
as the  holder  of the  right of first  refusal  under  of  Section  9.03 of the
Agreement.

                  NOW, THEREFORE, the Partners agree as follows:

     1. Section 9.03 of the Agreement is hereby amended by deleting  subsections
(b) and (c) thereof in their entirety and by substituting the language set forth
below:

                  (b) Upon receipt of such notice,  the  Partnership  shall have
         the right and option, exercisable at any time during a period of thirty
         (30) days from the date of the  Selling  Partner's  notice of the Offer
         (the "Option  Period"),  to purchase all or any portion of the Purchase
         Interest.  If the Partnership  elects to exercise its option,  it shall
         give  written  notice to the Selling  Partner and the sale and purchase
         shall be closed  within  thirty  (30) days  after the end of the Option
         Period.  Any purchase  made under this  paragraph  shall be on the same
         terms and conditions as contained in the Offer.

                  (c) If the  Partnership  does not elect to purchase all of the
         Purchase  Interest,  the Selling  Partner shall be free for a period of
         sixty (60) days after the expiration of the foregoing notice periods to
         sell the Purchase Interest to the purchaser named in the Offer upon the
         terms and conditions contained in the Offer, subject to the requirement
         of consent by the General Partner  pursuant to Section 9.02;  provided,
         that the said  purchaser  qualifies  as a Qualified  Purchaser.  In the
         event that the sale is not consummated within such sixty




<PAGE>


         (60)-day period, no sale shall be made without again complying with the
         provisions of this Section 9.03.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first written above.

                                    OHIO LITHO, INC., as General Partner and as
                                      Attorney-In-Fact for the Limited Partners


                                     By:_________________________________ (SEAL)

                                        ---------------------------------
                                              (Type Name and Title)

<PAGE>


                         AMENDMENT TO FIRST AMENDED AND
                    RESTATED AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                         OHIO MOBILE LITHOTRIPTER, LTD.

THIS  AMENDMENT,  effective  January 1, 2000,  is entered into by and among Ohio
Litho,  Inc.,  a  Delaware  corporation,  the  General  Partner  of Ohio  Mobile
Lithotripter,  Ltd., a Texas limited  partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.

                                                     RECITALS:
                                                     --------

                  A. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the  "Partners,"  entered into that  certain  First
Amended and Restated  Agreement of Limited  Partnership dated August 1, 1991, as
heretofore  amended  (the  "Agreement").  Capitalized  terms used herein and not
otherwise defined shall have the meanings given them in the Agreement.

     B. The  Partners  desire to amend the  Agreement  to delete in its entirety
Section 10.02(g) of the Agreement.

                  NOW, THEREFORE, the Partners agree as follows:

     1. Section 10.02(g) of the Agreement is hereby deleted in its entirety with
the effect that such provision shall be void and of no effect.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first written above.

                                     OHIO LITHO, INC., as General Partner and as
                                      Attorney-In-Fact for the Limited Partners


                                     By:_________________________________ (SEAL)

                                        ---------------------------------
                                                 (Type Name and Title)





<PAGE>
                         AMENDMENT TO FIRST AMENDED AND
                    RESTATED AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                         OHIO MOBILE LITHOTRIPTER, LTD.

     THIS  AMENDMENT,  effective  February 1, 2000, is entered into by and among
Ohio Litho,  Inc., a Delaware  corporation,  the General  Partner of Ohio Mobile
Lithotripter,  Ltd., a Texas limited  partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.
                                                     RECITALS:
                                                     --------

                  A. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the  "Partners,"  entered into that  certain  First
Amended and Restated  Agreement of Limited  Partnership dated August 1, 1991, as
heretofore  amended  (the  "Agreement").  Capitalized  terms used herein and not
otherwise defined shall have the meanings given them in the Agreement.

                  B. The  Partners  desire  to amend the  Agreement  to effect a
redesignation of the Partnership's geographic service area as defined in Section
16.16(a)  effective  on the date  appropriate  consents  are  received  from the
General Partner and Two Thirds in Interest of the Limited Partners.

                  NOW, THEREFORE, the Partners agree as follows:

     1.  Section  16.16(a) of the  Agreement  is hereby  amended by deleting the
following language from the last sentence thereof:

                    "(excluding any territory located in Cuyahoga County, Ohio)"

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first written above.

                                    OHIO LITHO, INC., as General Partner and as
                                      Attorney-In-Fact for the Limited Partners


                                   By:_________________________________ (SEAL)

                                      ---------------------------------
                                            (Type Name and Title)





<PAGE>






                               SECOND AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                       PACIFIC MEDICAL LIMITED PARTNERSHIP

                  THIS AMENDMENT,  effective as of the 1st day of January, 1999,
is entered into by and among  Lithotripters,  Inc., a North Carolina corporation
and the General Partner of Pacific Medical Limited Partnership, a Hawaii limited
partnership (the "Partnership"), and the Limited Partners of the Partnership.

                                    RECITALS:
                                    --------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the "Partners," entered into that certain Agreement
of Limited  Partnership of Pacific  Medical Limited  Partnership  dated April 1,
1996,  as  amended by that  certain  First  Amendment  to  Agreement  of Limited
Partnership of the Partnership, effective as of August 1, 1998.

          2.  The  Partners  desire  to  amend  the  Agreement  to  reflect  the
     assignment by  Lithotripters,  Inc. (the  "Assignor") of a two percent (2%)
     limited  partnership  interest in the  Partnership  to Charles D. Kim, Jr.,
     M.D. and a two percent (2%) limited partnership interest in the Partnership
     to Richard I. Tsou, M.D.

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A-1 is  deleted  in its  entirety  and  new
                  Schedule A-2, attached hereto, is substituted in its place.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first-above written.

                                                     GENERAL PARTNER:

                                                     Lithotripters, Inc.

                                         By:/s/ Joseph Jenkins, M.D.
                                         ---------------------------
                                                     Joseph Jenkins, M.D.
                                                     President

                                              ALL THE LIMITED PARTNERS OF THE
                                              PARTNERSHIP WHOSE NAMES APPEAR ON
                                              SCHEDULE A-2

                                         By:/s/ Joseph Jenkins, M.D.      (SEAL)
                                         ---------------------------
                                                 Joseph Jenkins, M.D.,
                                                 Attorney-in-Fact*

*  Pursuant  to a  Power  of  Attorney  given  by the  Limited  Partners  in the
Agreement.

                                                       1-




<PAGE>





                                                                    SCHEDULE A-2

                        Schedule of Partnership Interests

                       PACIFIC MEDICAL LIMITED PARTNERSHIP

           CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND GUARANTIES

                            Cash                                    Percentage

General Partner          Contribution           Guaranty(1)           Interest

Lithotripters, Inc.      $47,688                   $330,402.80               20%

Limited Partners

Lithotripters, Inc.      $47,250                   $181,721.54               11%

Antonio Tan              $10,000                    $66,080.56                4%

Robert Carlile           $10,000                    $66,080.56                4%

Herbert Chinn            $10,000                    $66,080.56                4%

Rick Davis               $10,000                    $66,080.56                4%

Terry Yee                 $5,000                    $33,040.28                2%

William Flanagan          $2,250                    $16,520.14                1%

Keith Mooney              $2,500                    $16,520.14                1%

Franklin Clark            $2,250                    $16,520.14                1%

Thomas Jordan             $2,250                    $16,520.14                1%

William Jordan            $2,250                    $16,520.14                1%

Philip Gallina            $2,250                    $16,520.14                1%

William Grine             $2,250                    $16,520.14                1%

Jack Cassell              $2,500                    $16,520.14                1%

Marilyn Hata             $10,000                    $66,080.56                4%

Charles D. Kim, Jr.        N/A(2)              $33,040.28(3)                  2%

David Kychenbecker        $10,000                   $66,080.56                4%





<PAGE>



                            Cash                                      Percentage

General Partner          Contribution                Guaranty(1)       Interest

Douglas Gary Lattimer    $10,000                    $66,080.56                4%

William Yarborough       $10,000                    $66,080.56                4%

Dan Myers                 $2,250                    $16,520.14                1%

Jim Brady                 $2,250                    $16,520.14                1%

Tom Mobley                $2,250                    $16,520.14                1%

Timothy Quillen           $2,250                    $16,520.14                1%

James Monroe              $2,250                    $16,520.14                1%

J. Ronald Smith           $2,250                    $16,520.14                1%

David M. Coussens         $2,500                    $16,520.14                1%

Denis E. Healey           $2,500                    $16,520.14                1%

Lewis F. Russell          $2,500                    $16,520.14                1%

Alan Terry                $2,250                    $16,520.14                1%

Anthony Rand              $2,250                    $16,520.14                1%

Joseph Jenkins            $2,250                    $16,520.14                1%

Rene Sepulveda            $2,500                    $16,520.14                1%

Robert McAlpine           $2,250                    $16,520.14                1%

Lance Templeton           $2,500                    $16,520.14                1%

Lelan C. Byrd             $2,500                    $16,520.14                1%

Donald A. Stewart         $2,500                    $16,520.14                1%

Larry Raithaus             N/A(2)              $33,040.28(3)                  2%

Richard I. Tsou            N/A(2)              $33,040.28(3)                  2%

William Yarborough, M.D.,
    Inc.                   N/A(2)              $66,080.56(3)                  4%

         TOTAL:         $238,438                 $1,652,014.00              100%
                        ========                 =============              ====




<PAGE>



(1)      Represents the estimated  principal portion of each Partner's  guaranty
         obligation,  as each Partner's  obligation under the Guaranty  includes
         not only principal,  but also (as provided in the Guaranty) accrued and
         unpaid interest,  late payment  penalties and all costs incurred by the
         Bank in collecting any defaulted obligations.

(2) Larry Raithaus,  M.D.,  Charles D. Kim, Jr., M.D., Richard I. Tsou, M.D. and
William Yarborough,  M.D., Inc. received their limited partnership  interests by
an  assignment   from   Lithotripters,   Inc.  and  therefore  made  no  capital
contributions to the Partnership.

(3)  Pursuant to the terms of the  assignments  by  Lithotripters,  Inc.,  Larry
Raithaus,  M.D.,  Charles D. Kim, Jr., M.D.,  Richard I. Tsou,  M.D. and William
Yarborough,  M.D.,  Inc.  assumed their pro rata portion of the initial  limited
partner guaranty of Lithotripters, Inc.
<PAGE>



                               SECOND AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                 TEXAS LITHOTRIPSY LIMITED PARTNERSHIP VII, L.P.


     THIS  AMENDMENT,  effective  as of the 1st day of January,  1999 is entered
into by and among  Lithotripters,  Inc., a North  Carolina  corporation  and the
General  Partner  of  Texas  Lithotripsy  Limited  Partnership  VII,  L.P.  (the
"Partnership"), and the Limited Partners of the Partnership.

                                R E C I T A L S:
                                 ---------------

                  1. The General  Partner and the Initial  Limited Partner named
therein  entered into that certain  Agreement  of Limited  Partnership  of Texas
Lithotripsy  Limited  Partnership  VII, L.P.,  dated as of September 4, 1998, as
amended by that certain  Amendment to  Agreement of Limited  Partnership  of the
Partnership, effective as of October 7, 1998 (the "Agreement").

                  2. The General  Partner and the undersigned  Limited  Partners
(collectively,  the "Partners") desire to further amend the Agreement to reflect
the successful  closing of the Merger pursuant to the Merger Agreement,  and the
assignment by William Mulchin,  M.D. of his .29893238%  limited partner interest
in the Partnership to Fifth Street Corp.

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A is  deleted  in  its  entirety  and a new
                           Schedule A-1,  attached hereto, is substituted in its
                           place.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                                                     GENERAL PARTNER:

                                                     Lithotripters, Inc.


                                                    By:/s/ Joseph Jenkins, M.D.
                                                    ---------------------------
                                                            Joseph Jenkins, M.D.
                                                            President




                                                        -1-


<PAGE>





                                                     ALL THE LIMITED PARTNERS OF
                                                     THE PARTNERSHIP WHOSE NAMES
                                                     APPEARED ON SCHEDULE A

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                            Joseph Jenkins, M.D.
                                                            Attorney-in-Fact1
- --------
1Pursuant to a Power of Attorney given by the Limited Partners in the Agreement.



                                                        -2-


<PAGE>






                                                                    SCHEDULE A-1

                        Schedule of Partnership Interests

                 TEXAS LITHOTRIPSY LIMITED PARTNERSHIP VII, L.P.
                 -----------------------------------------------



General Partner                                        Percentage Interest
- ---------------                                        -------------------
Lithotripters, Inc.                                        20.80897806%
2008 Litho Place
Fayetteville, NC 28304
Limited Partners

Robert Admire                                               0.41200000%
Joyce Allen                                                 0.29893238%
Mark Allen                                                  0.20600000%
Thomas Arnold                                               1.15074320%
John Ballard, III                                           0.29893238%
Charles Bamberger                                           1.74054700%
Marc Barrett                                                2.30148640%
James Brady                                                 0.20600000%
Franklin Clark                                              0.20600000%
James Cochran                                               1.29537367%
Donald Cook                                                 0.29893238%
Stephen Corwin                                              0.29893238%
Philip Damstra                                              0.38375240%
Jules Delaune                                               0.57537160%
Ruth Delaune                                                0.57537160%
Robert Dowling                                              0.38375240%




                                                        -3-


<PAGE>





Limited Partners                                       Percentage Interest
- ----------------                                       -------------------
J. Stephen Dryden                                           0.20600000%
Richard Dulany                                              0.20600000%
Glenn Dunnington                                            0.29893238%
Christopher Fetner                                          0.82400000%
Fifth Street Corp                                           2.09252669%
Larry Frank                                                 0.20600000%
Gerald Frankel                                              0.82400000%
William Freeborn                                            0.82400000%
Alan Freeman                                                0.29893238%
Philip Gallina                                              0.20600000%
Glen Goldsmith                                              0.29893238%
William Grine                                               0.20600000%
Scott Hassell                                               0.41200000%
Wayne Hey                                                   0.76699080%
A. Mason Holden                                             0.29893238%
Ira Hollander                                               1.72611480%
Joseph Jenkins                                              0.20600000%
Dan Johnson                                                 1.43842900%
John Johnson                                                0.57537160%
Sid Jones                                                   1.15074320%
Lillian Jordan                                              0.57537160%
Thomas Jordan                                               0.20600000%
William Jordan                                              0.20600000%
T.S. Kent                                                   0.29893238%




                                                        -4-


<PAGE>





Farid Khoury                                                0.20600000%
Mario Labardini                                             0.20600000%
J.L. LaManna, III                                           0.29893238%
Hugh Lamensdorf                                             1.15074320%
Edward Lee                                                  1.15074320%
Stephen Lieman                                              0.61800000%
Lithotripters, Inc.                                        22.05669678%
Barney Maddox                                               0.29893238%
Donald McKay                                                0.61800000%
William Mitchell                                            0.29893238%
Thomas Mobley                                               0.20600000%
Yondell Moore                                               0.20600000%
Dan Myers                                                   0.20600000%
Jerry Newton                                                0.29893238%
Denis Ortiz                                                 0.38375240%
Paris Urology Assoc. Pension                                0.59786477%
Allen Plotkin                                               0.29893238%
Drew Pumphrey                                               1.53454700%
Anthony Rand                                                0.20600000%
Richard Reese                                               0.59786477%
Jack Rice                                                   0.29893238%
 Edward Rietze Estate                                       0.20600000%
William Risk                                                1.49466192%
Donald Ross                                                 0.57537160%




                                                        -5-


<PAGE>




James Saalfield                                             0.97299080%
Rashinda Singh                                              0.57537160%
Southwest Lithotripter Partners                             8.70117438%
John Staub                                                  0.29893238%
Martha Storrie                                              2.15254700%
Mark Story                                                  2.01380060%
Robert Stroud                                               0.38375240%
Roger Stuart                                                0.20600000%
Agif Syed                                                   0.29893238%
Alan Terry                                                  0.20600000%
Addison Thurman                                             1.15074320%
Arthur Tijerina                                             1.79359431%
Eugene Todd                                                 0.59786477%
Michael Walter                                              0.57537160%
R.D. West                                                   0.19928826%
Jeannie Westerburg                                          0.19928826%
Robert Westerburg                                           0.19928826%
Roger Wolfert                                               0.29893238%
                                                            -----------
TOTAL                                                         100%





                                                        -6-


<PAGE>


                               THIRD AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                 TEXAS LITHOTRIPSY LIMITED PARTNERSHIP VII, L.P.


     THIS  AMENDMENT,  effective as of the 2nd day of February,  1999 is entered
into by and among  Lithotripters,  Inc., a North  Carolina  corporation  and the
General  Partner  of  Texas  Lithotripsy  Limited  Partnership  VII,  L.P.  (the
"Partnership"), and the Limited Partners of the Partnership.

                                R E C I T A L S:
                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the "Partners," entered into that certain Agreement
of Limited Partnership of Texas Lithotripsy Limited Partnership VII, L.P., dated
as of  September 4, 1998,  as amended by that certain  Amendment to Agreement of
Limited Partnership of the Partnership,  effective as of October 7, 1998, and as
further  amended  by that  certain  Second  Amendment  to  Agreement  of Limited
Partnership   of  the   Partnership,   effective  as  of  January   1,1999  (the
"Agreement").

                  2. The  Partners  desire to  further  amend the  Agreement  to
reflect  the  Partners's  adjusted  Percentage   Interests  resulting  from  the
successful  closing  of  the  offering  of  limited  partner  interests  in  the
Partnership  pursuant  to  the  Partnership's   Confidential  Private  Placement
Memorandum dated September 4, 1998, as amended,  and the subsequent admission of
new Limited Partners to the Partnership.

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A-1 is  deleted in its  entirety  and a new
                           Schedule A-2,  attached hereto, is substituted in its
                           place.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                                              GENERAL PARTNER:

                                              Lithotripters, Inc.


                                                    By:/s/ Joseph Jenkins, M.D.
                                                    ---------------------------
                                                          Joseph Jenkins, M.D.
                                                          President




                                                        -1-


<PAGE>





                                                     ALL THE LIMITED PARTNERS OF
                                                     THE PARTNERSHIP WHOSE NAMES
                                                     APPEARED ON SCHEDULE A-1

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                            Joseph Jenkins, M.D.
                                                            Attorney-in-Fact1
- --------
1Pursuant to a Power of Attorney given by the Limited Partners in the Agreement.



                                                        -2-


<PAGE>



                                                                    SCHEDULE A-2

                        Schedule of Partnership Interests

                 TEXAS LITHOTRIPSY LIMITED PARTNERSHIP VII, L.P.
                 -----------------------------------------------


General Partner                                           Percentage Interest
- ---------------                                           -------------------
Lithotripters, Inc.                                        19.22749573%
2008 Litho Place
Fayetteville, NC 28304
Limited Partners

Robert Admire                                               0.38068800%
Joyce Allen                                                 0.27621352%
Mark Allen                                                  0.19034400%
Thomas Arnold                                               328672%
Steven Ash                                                  0.57000000%
John Ballard, III                                           0.27621352%
Charles Bamberger                                           1.60826543%
Marc Barrett                                                2.12657343%
Baylor Health Care System                                   1.14000000%
James Brady                                                 0.19034400%
Harold Calhoun                                              0.19000000%
David Casey                                                 0.19000000%
Franklin Clark                                              0.19034400%
James Cochran                                               1.19692527%
Michael Collini                                             0.57000000%
Donald Cook                                                 0.27621352%
Robert Corwin                                               0.57000000%
Stephen Corwin                                              0.27621352%
Philip Damstra                                              0.35458722%
Jules Delaune                                               0.53164336%
Ruth Delaune                                                0.53164336%

Limited Partners                                          Percentage Interest
- ----------------                                          -------------------
Robert Dowling                                              0.35458722%
J. Stephen Dryden                                           0.19034400%
Richard Dulany                                              0.19034400%
Glenn Dunnington                                            0.27621352%
Kurt Evans                                                  0.19000000%
John Fairbanks                                              0.57000000%
Christopher Fetner                                          0.76137600%
Fifth Street Corp                                           1.93349466%
Joshua Fine                                                 0.57000000%
Myron Fine                                                  0.19000000%
Manny Forkowitz                                             0.57000000%
Larry Frank                                                 0.19034400%
Gerald Frankel                                              0.76137600%
William Freeborn                                            0.76137600%
Alan Freeman                                                0.27621352%
Steven Frost                                                0.57000000%
Philip Gallina                                              0.19034400%
Kenneth Goldberg                                            0.57000000%
Glen Goldsmith                                              0.27621352%
Mike Goldstein                                              0.57000000%
Carole L. Gordon                                            0.190000000%
Nathan Graves                                               0.57000000%
Rufus Green                                                 0.38000000%
William Grine                                               0.19034400%
Scott Hassell                                               0.38068800%
Wayne Hey                                                   0.70869950%
A. Mason Holden                                             0.27621352%
Ira Hollander                                               1.59493008%



                                                        -3-


<PAGE>



Limited Partners                                          Percentage Interest
- ----------------
Allen Van Horn                                              0.57000000%
Joseph Jenkins                                              0.19034400%
Dan Johnson                                                 1.32910840%
John Johnson                                                0.53164336%
Sid Jones                                                   1.06328672%
Lillian Jordan                                              0.53164336%
Thomas Jordan                                               0.19034400%
William Jordan                                              0.19034400%
T.S. Kent                                                   0.27621352%
Farid Khoury                                                0.19034400%
Mario Labardini                                             0.19034400%
J.L. LaManna, III                                           0.27621352%
Hugh Lamensdorf                                             1.06328672%
Jeffrey H. Landau                                           0.57000000%
Edward Lee                                                  1.06328672%
Kenneth Licker                                              0.19000000%
Stephen Lieman                                              0.57103200%
Lithotripters, Inc.                                        15.06038783%
Barney Maddox                                               0.27621352%
James Mason                                                 0.19000000%
Roy Carrington Mason                                        0.19000000%
Donald McKay                                                0.57103200%
William Mitchell                                            0.27621352%
Thomas Mobley                                               0.19034400%
Frank Moore, III                                            0.5700000%
Yondell Moore                                               0.19034400%
Dan Myers                                                   0.19034400%
Jerry Newton                                                0.27621352%



                                                        -4-


<PAGE>



Limited Partners                                          Percentage Interest
- ----------------
Denis Ortiz                                                 0.35458722%
Paris Urology Assoc. Pension                                0.55242705%
Allen Plotkin                                               0.27621352%
Drew Pumphrey                                               1.41792143%
Anthony Rand                                                0.19034400%
Richard Reese                                               0.55242705%
Jack Rice                                                   0.27621352%
 Edward Rietze Estate                                       0.19034400%
William Risk                                                1.38106762%
Donald Ross                                                 0.53164336%
James Saalfield                                             0.89904350%
Jeff Sanders                                                0.57000000%
Nabel Sayed                                                 0.38000000%
Ben Schnitzer                                               0.19000000%
Roger Schoenvogel                                           0.57000000%
Rashinda Singh                                              0.53164336%
Southwest Lithotripter Partners                             7.45776513%
Frank Splann                                                0.19000000%
John Staub                                                  0.27621352%
Donald Stewart                                              0.57000000%
Martha Storrie                                              1.98895343%
Mark Story                                                  1.86075175%
Robert Stroud                                               0.35458722%
Roger Stuart                                                0.19034400%
Agif Syed                                                   0.27621352%
Alan Terry                                                  0.19034400%
Addison Thurman                                             1.06328672%
Arthur Tijerina                                             1.65728114%




                                                        -5-


<PAGE>


Limited Partners                                          Percentage Interest
- ----------------
Eugene Todd                                                 0.55242705%
Michael Walter                                              0.53164336%
R.D. West                                                   0.18414235%
Jeannie Westerburg                                          0.18414235%
Robert Westerburg                                           0.18414235%
Roger Wolfert                                               0.27621352%
                                                            -----------
TOTAL                                                        100%





                                                        -6-


<PAGE>
                               FOURTH AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                 TEXAS LITHOTRIPSY LIMITED PARTNERSHIP VII, L.P.



     THIS AMENDMENT,  effective as of the 1st day of March, 1999 is entered into
by and among  Lithotripters,  Inc., a North Carolina corporation and the General
Partner of Texas Lithotripsy Limited Partnership VII, L.P. (the  "Partnership"),
and the Limited Partners of the Partnership.

                                                 R E C I T A L S:
                                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the "Partners," entered into that certain Agreement
of Limited Partnership of Texas Lithotripsy Limited Partnership VII, L.P., dated
as of  September 4, 1998,  as amended by that certain  Amendment to Agreement of
Limited  Partnership  of the  Partnership,  effective as of October 7, 1998,  as
further  amended  by that  certain  Second  Amendment  to  Agreement  of Limited
Partnership of the Partnership,  effective as of January 1,1999,  and as further
amended by that certain Third  Amendment to Agreement of Limited  Partnership of
the Partnership effective as of February 2, 1999 (the "Agreement").

                  2. The  Partners  desire to  further  amend the  Agreement  to
reflect  the  Partners'  adjusted   Percentage   Interests  resulting  from  the
assignment by each of Mark Allen, M.D.  ("Allen"),  J. Scott Hassell ("Hassell")
and Steven Lieman  ("Lieman") of their entire limited  partnership  interests in
the  Partnership  to  the  Partnership.   As  a  consequence  of  the  foregoing
assignments,  Allen,  Hassell and Lieman are no longer  limited  partners of the
Partnership as of the date hereof.

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A-2 is  deleted in its  entirety  and a new
                           Schedule A-3,  attached hereto, is substituted in its
                           place.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                                                     GENERAL PARTNER:

                                                     Lithotripters, Inc.


                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                           Joseph Jenkins, M.D.
                                                           President



                                                        -1-


<PAGE>





                                                     ALL THE LIMITED PARTNERS OF
                                                     THE PARTNERSHIP WHOSE NAMES
                                                     APPEARED ON SCHEDULE A-2

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                            Joseph Jenkins, M.D.
                                                            Attorney-in-Fact
- --------
1Pursuant to a Power of Attorney given by the Limited Partners in the Agreement.



                                                        -2-


<PAGE>



                                                                    SCHEDULE A-2

                        Schedule of Partnership Interests

                 TEXAS LITHOTRIPSY LIMITED PARTNERSHIP VII, L.P.
                 -----------------------------------------------


General Partner                                          Percentage Interest
- ---------------                                          -------------------
Lithotripters, Inc.                                          19.449629%
2008 Litho Place
Fayetteville, NC 28304
Limited Partners                                         Percentage Interest
- ----------------                                         ------------------
Robert Admire                                                 0.385086%
Joyce Allen                                                   0.279404%
Thomas Arnold                                                 1.075570%
Steven Ash                                                    0.576585%
John Ballard, III                                             0.279404%
Charles Bamberger                                             1.626845%
Marc Barrett                                                  2.151141%
Baylor Health Care System                                     1.153170%
James Brady                                                   0.192543%
Harold Calhoun                                                0.192195%
David Casey                                                   0.192195%
Franklin Clark                                                0.192543%
James Cochran                                                 1.210753%
Michael Collini                                               0.576585%
Donald Cook                                                   0.279404%
Robert Corwin                                                 0.576585%
Stephen Corwin                                                0.279404%
Philip Damstra                                                0.358684%
Jules Delaune                                                 0.537785%
Ruth Delaune                                                  0.537785%
Robert Dowling                                                0.358684%
J. Stephen Dryden                                             0.192543%



                                                        -3-


<PAGE>



2008 Litho Place

Richard Dulany                                                0.192543%
Glenn Dunnington                                              0.279404%
Kurt Evans                                                    0.192195%
John Fairbanks                                                0.576585%
Christopher Fetner                                            0.770172%
Fifth Street Corp                                             1.955832%
Joshua Fine                                                    .576585%
Myron Fine                                                    0.192195%
Manny Forkowitz                                               0.576585%
Larry Frank                                                   0.192543%
Gerald Frankel                                                0.770172%
William Freeborn                                              0.770172%
Alan Freeman                                                  0.279404%
Steven Frost                                                  0.576585%
Philip Gallina                                                0.192543%
Kenneth Goldberg                                              0.576585%
Glen Goldsmith                                                0.279404%
Mike Goldstein                                                0.576585%
Carole L. Gordon                                              0.192195%
Nathan Graves                                                 0.576585%
Rufus Green                                                   0.384390%
William Grine                                                 0.192543%
Wayne Hey                                                     0.716887%
A. Mason Holden                                               0.279404%
Ira Hollander                                                 1.613356%
Joseph Jenkins                                                0.192543%
Dan Johnson                                                   1.344463%
John Johnson                                                  0.537785%
Sid Jones                                                     1.075570%



                                                        -4-


<PAGE>



2008 Litho Place

Lillian Jordan                                                0.537785%
Thomas Jordan                                                 0.192543%
William Jordan                                                0.192543%
T.S. Kent                                                     0.279404%
Farid Khoury                                                  0.192543%
Mario Labardini                                               0.192543%
J.L. LaManna, III                                             0.279404%
Hugh Lamensdorf                                               1.075570%
Jeffrey H. Landau                                             0.576585%
Edward Lee                                                    1.075570%
Kenneth Licker                                                0.192195%
Lithotripters, Inc.                                          15.233413%
Barney Maddox                                                 0.279404%
James Mason                                                   0.192195%
Roy Carrington Mason                                          0.192195%
Donald McKay                                                  0.577629%
William Mitchell                                              0.279404%
Thomas Mobley                                                 0.192543%
Frank Moore, III                                              0.576585%
Yondell Moore                                                 0.192543%
Dan Myers                                                     0.192543%
Jerry Newton                                                  0.279404%
Denis Ortiz                                                   0.358684%
Paris Urology Assoc. Pension Plan                             0.558809%
Allen Plotkin                                                 0.279404%
John Pumphrey                                                 1.434302%
Anthony Rand                                                  0.192543%
Richard Reese                                                 0.558809%
Jack Rice                                                     0.279404%



                                                        -5-


<PAGE>


2008 Litho Place

 Edward Rietze Estate                                         0.192543%
William Risk                                                  1.397023%
Donald Ross                                                   0.537785%
James Saalfield                                               0.909430%
Jeff Sanders                                                  0.576585%
Nabel Sayed                                                   0.384390%
Ben Schnitzer                                                 0.192195%
Roger Schoenvogel                                             0.576585%
Rashinda Singh                                                0.537785%
Southwest Lithotripter Partners                               7.543922%
Frank Splann                                                  0.192195%
John Staub                                                    0.279404%
Donald Stewart                                                0.576585%
Martha Storrie                                                2.011931%
Mark Story                                                    1.882248%
Robert Stroud                                                 0.358684%
Roger Stuart                                                  0.192543%
Agif Syed                                                     0.279404%
Alan Terry                                                    0.192543%
Addison Thurman                                               1.075570%
Arthur Tijerina                                               1.676427%
Eugene Todd                                                   0.558809%
Allen Van Horn                                                0.576585%
Michael Walter                                                0.537785%
R.D. West                                                     0.186270%
Jeannie Westerburg                                            0.186270%
Robert Westerburg                                             0.186270%
Roger Wolfert                                                 0.279404%
                                                              ---------
TOTAL                                                          100%




                                                        -6-


<PAGE>



                               FOURTH AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                   SAN DIEGO LITHOTRIPTERS LIMITED PARTNERSHIP

                  THIS  AMENDMENT,  effective  as of the 15TH  day of  February,
1999,  is  entered  into by and  among  Lithotripters,  Inc.,  a North  Carolina
corporation  and  the  General  Partner  of  San  Diego  Lithotripters   Limited
Partnership,  a California  limited  partnership  (the  "Partnership"),  and the
Limited Partners of the Partnership.

                                                 R E C I T A L S:
                                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred  to as  the  "Partners,"  are  parties  to  that  certain
Agreement of Limited Partnership of San Diego Lithotripters Limited Partnership,
as amended (the "Agreement").

                  2. Effective as of February 15, 1999, the General  Partner and
the  requisite  percentage of the Limited  Partners  consented in writing to the
following  amendments to the Agreement,  such amendments  intended to: (i) allow
the General  Partner the  authority to  periodically  offer and sell  additional
limited  partner  interests  (a  "Dilution  Offering")  to local  investors;(ii)
clarify and strengthen the  noncompetition  provisions of Articles 15.3 and 18.4
of the  Agreement;  (iii) add a new  provision  to the  Agreement to prevent the
disclosure  of  Confidential   Partnership   Information  that  might  harm  the
Partnership and its Partners;  and (iv) allow the General  Partner,  in its sole
discretion, to elect to assign to the Partnership its rights under Article 18 of
the Agreement to purchase the Partnership Interest of any deceased, insolvent or
competing Limited Partner:

                  NOW,  THEREFORE,  in accordance with Articles 29 and 30 of the
Partnership Agreement and pursuant to the written consent of the General Partner
and the requisite  percentage of the Limited Partners,  the parties hereto agree
as follows:

                           The  Agreement  is  hereby  amended  as set  forth in
                           Exhibits A, B and C attached hereto.



                                                        -1-


<PAGE>




                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                           GENERAL PARTNER:

                           LITHOTRIPTERS, INC., a North Carolina corporation and
                                   sole general partner of the Partnership

                                   By:_________________________________________
                                Title:________________________________________



                                                 ALL THE LIMITED PARTNERS OF
                                                 THE PARTNERSHIP WHOSE NAMES
                                                 APPEARED ON SCHEDULE A-3

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                     Joseph Jenkins, M.D.
                                                     Attorney-in-Fact*
- --------
     *Pursuant  to a Power of  Attorney  given by the  Limited  Partners  in the
Agreement.

W#876952.1

                                                        -2-


<PAGE>



                                    EXHIBIT A

                           DILUTION OFFERING AMENDMENT

1.       Capitalized  terms used in this Exhibit and not otherwise defined shall
         have  the  same  meaning  as  provided  in  the  Agreement  of  Limited
         Partnership (the  "Partnership  Agreement") of San Diego  Lithotripters
         Limited Partnership (the "Partnership").

2.       The purpose of this Exhibit is to set forth a proposed amendment to the
         Partnership Agreement that would give the General Partner the authority
         periodically  to offer and sell additional  limited  partner  interests
         ("Dilution  Offerings") to local investors who are not Limited Partners
         in the Partnership ("Qualified Investors").  As required by Articles 28
         and 29 of the  Partnership  Agreement,  to be effective  this amendment
         must  be  approved  by  the  Partners  representing  two-thirds  of the
         aggregate interests in the Partnership.

3.   The purposes of a Dilution Offering are (i) to raise additional capital for
     any valid  Partnership  purpose,  and (ii) to assure the highest quality of
     patient care by admitting  Qualified  Investors to the Partnership who will
     be dedicated and motivated as owners to follow the Partnership's  treatment
     protocol,  and comply  with its  quality  assurance  and  outcome  analysis
     programs.  Any additional  capital raised by the  Partnership in a Dilution
     Offering  can be used for any  legitimate  Partnership  purpose,  including
     upgrading the  Partnership's  Lithostar(TM)Mobile  System,  and/or upon the
     vote of a Majority in Interest of the Limited Partners,  the acquisition of
     an additional lithotripter and transport vehicle.

4.   In the  event  the  Dilution  Offering  Amendment  receives  the  requisite
     approval of the Limited Partners,  the General Partner intends to conduct a
     Dilution  Offering for the purposes of raising  additional  capital for (i)
     upgrading and refurbishing the Partnership's  Lithostar(TM)  Mobile System,
     and (ii)  acquiring  and operating a new Storz  Modulith(R)SLX-T  ("SLX-T")
     model  lithotripter and a new mobile transport vehicle for transporting the
     SLX-T from site to site in the  Partnership's  current  service area. It is
     estimated  that  the cost  for the  SLX-T  and  transport  vehicle  will be
     approximately  $525,000. In the event the proceeds of the Dilution Offering
     alone are insufficient to fund the necessary  upgrades of the Lithostar(TM)
     Mobile  System and the purchases of the SLX-T and  transport  vehicle,  the
     necessary additional funds will be borrowed (the "Loan") by the Partnership
     from a commercial financial institution  acceptable to the General Partner.
     The General Partner  anticipates that the Partnership will be the principal
     guarantor of the Loan.  Therefore,  the Limited Partners will not be liable
     for such debt individually.  However, payments by the Partnership under the
     Loan  will  impact  the cash flow of the  Partnership,  and  therefore  the
     distributions  to be  received  by the Limited  Partners  from  Partnership
     operations during the term of the Loan.

         The General Partner believes that the acquisition of a new lithotripter
         and transport vehicle are in the best interests of the Partnership. Due
         to certain market forces existing in the

W#876952.1

                                                        -3-


<PAGE>



         Partnership's   current   service  area,  the  demand  for  alternative
         technology  to  the  Partnership's  Lithostar(TM)  has  increased.  The
         General Partner and the Partnership's Medical Director believe that the
         best means for the  Partnership  to address  such  demand,  and thereby
         remain competitive in the Partnership's  market area, is to provide the
         equipment  technology  available with the SLX-T.  The General  Partner,
         however,  reserves the right to pursue  technology other than the SLX-T
         if such  alternative  technology is more  beneficial to the Partnership
         and the Limited Partners.  As required by Article 28 of the Partnership
         Agreement, the acquisition of a new lithotripter, and the Partnership's
         incurrence of debt in excess of $100,000 per year (if necessary to fund
         the acquisition of the  lithotripter  and transport  vehicle),  must be
         approved  by the  General  Partner  and a Majority  in  Interest of the
         Limited Partners.

5.       Any sale of limited  partner  interests  to  Qualified  Investors  will
         result in the  proportionate  dilution  of the  Partnership  Percentage
         Interests of the existing Partners;  i.e., the interests of the General
         Partner  and the  Limited  Partners in  Partnership  allocations,  cash
         distributions  and voting rights will be  proportionately  reduced by a
         successful Dilution Offering.

6.       The  Percentage  Interests of the existing  Partners  cannot be diluted
         through  Dilution  Offerings by more than 20% in the aggregate  without
         the  prior  written  consent  of a  Majority  in  Interest  of all  the
         Partners.  Without  obtaining  this  additional  consent,  the existing
         Partners  cannot  be  diluted  to less  than  80% of  their  Percentage
         Interest ownership at the time of this Amendment.

7.       The  General  Partner has  determined  that the  purchase  price per 1%
         Partnership  Interest offered in the initial planned Dilution  Offering
         will be at its fair market value as determined by an independent  third
         party appraiser (Philpott, Ball & Company). The price for Units sold in
         future  Dilution  Offerings  also  must be at a price no less than fair
         market  value as  determined  by the General  Partner and a third party
         appraiser.

8.       Upon  the  successful  sale  of  Partnership  Interests  in a  Dilution
         Offering,  the General Partner will prepare and attach a new Schedule A
         to the  Partnership  Agreement  to reflect (i) the  Partners'  adjusted
         Percentage Interests in the Partnership,  and (ii) the admission of the
         new Limited Partners to the Partnership.



                                                        -4-


<PAGE>



                                    EXHIBIT B

                          NONCOMPETITION PROVISION AND
                          ----------------------------
                      CONFIDENTIALITY PROVISION AMENDMENTS
                       --------------- --------- ---------


                  Capitalized  terms  used in  this  Exhibit  and not  otherwise
defined  shall have the same  meaning as  provided in the  Agreement  of Limited
Partnership (the  "Partnership  Agreement") of San Diego  Lithotripters  Limited
Partnership (the "Partnership"), and any amendments thereto.

                                        Noncompetition Provision Amendment

                  Article 15.3 of the Partnership Agreement is hereby amended by
deleting the current  provision in its entirety and by substituting the language
set forth below:

                           15.3 Outside  Activities.  The Limited Partners agree
         that  they  owe  fiduciary   duties  to  the  Partnership   and,  as  a
         consequence,  each Limited  Partner (that is not the General Partner or
         an  Affiliate of the General  Partner)  agrees that he or she shall not
         engage in "Outside  Activities" (as defined below) in the "Market Area"
         (as  defined  below)  while  he or  she  is a  Limited  Partner  in the
         Partnership.   The  phrase  "Outside   Activities"  means  directly  or
         indirectly owning, leasing or subleasing a lithotripter (or any similar
         equipment or competing devices used for treating renal or biliary stone
         disease).  Prohibited  indirect  ownership  shall include the direct or
         indirect ownership of any interest in a business venture (through stock
         ownership,  partnership  interest ownership,  ownership by or through a
         close family  member,  or as otherwise  determined in good faith by the
         General Partner) involving the ownership,  purchase,  lease,  sublease,
         promotion,  management  or  operation  of a  lithotripter  (or  similar
         equipment or competing devices used for treating renal or biliary stone
         disease),  unless the General Partner  determines that such activity by
         the Limited  Partners is not  detrimental  to the best interests of the
         Partnership.

                           Upon  the   termination  or  transfer  of  a  Limited
         Partner's  interest  in the  Partnership  for any  reason,  including a
         transfer  pursuant to Article  18.4  hereof,  the  withdrawing  Limited
         Partner shall not, for a period of two (2) years  following the date of
         his or her withdrawal,  engage in any Outside Activities in any "Market
         Area" in which the  Partnership is  transacting  business or within the
         prior  twelve  months  has   transacted   business   (the   "Restricted
         Facilities").  For the purposes of this Article 15.3,  the term "Market
         Area"  shall  mean  (i)  the  area  within  a ten  mile  radius  of any
         Restricted  Facility,  but if such  area is  determined  by a court  of
         competent  jurisdiction  to be too  broad,  then it shall mean (ii) the
         area within a five mile radius of any Restricted Facility,  but if such
         area is determined by a court of competent jurisdiction to be too broad
         then it shall  mean  (iii)  the area  within a two mile  radius  of any
         Restricted Facility.



                                                        -5-


<PAGE>



                           In the event a Limited  Partner wishes and intends to
         engage in an Outside  Activity in a Market Area, he or she must provide
         written notice of such intent to the General  Partner prior to engaging
         in the Outside Activity. The written notice shall be deemed an election
         by the Limited Partner to withdraw from the Partnership (the "Notice of
         Withdrawal"),  and shall give the  General  Partner  and/or the Limited
         Partners the purchase rights as provided in Article 18.4 hereof.  After
         the Notice of Withdrawal,  the former Limited  Partner may engage in an
         Outside  Activity in the Market  Area only after  waiting the period of
         two years specified in this Article 15.3. In the event of breach of the
         waiting period,  the Partnership shall be entitled to any remedy at law
         or equity with respect to such breach,  including without limitation an
         injunction or suit for damages.

                           If a Limited Partner during his or her  participation
         in the  Partnership  engages in an Outside  Activity  in a Market  Area
         without  first  notifying  the  General  Partner in  violation  of this
         Article  15.3,  the  Limited  Partner  shall be deemed to have  given a
         Notice of  Withdrawal  on the date the General  Partner  first  becomes
         aware of the Limited  Partner's  Outside  Activity in the Market  Area.
         Upon receiving a Limited  Partner's  Notice of Withdrawal or equivalent
         thereof,  the General  Partner and/or  Limited  Partners may invoke the
         purchase  rights  provided in Article 18.4 and shall be entitled to any
         other  remedy  at  law  or  equity  including  without   limitation  an
         injunction or suit for damages.

                  Article 18.4 of the Partnership Agreement is hereby amended by
deleting the current  provision in its entirety and by substituting the language
set forth below.

                           18.4 Breach of Article 15.3. In the event the General
         Partner  either  receives a Notice of Withdrawal as provided in Article
         15.3 or  receives  notice  of a breach  of  Article  15.3 by a  Limited
         Partner (the  "Defaulting  Limited  Partner"),  the General Partner may
         elect, in its sole  discretion,  to treat such event as a default under
         this  Agreement and enforce the provisions of this Article 18.4. If the
         General  Partner elects to enforce the provisions of this Article 18.4,
         the General  Partner  shall give written  notice of such  election (the
         "Notice of Default") to the Defaulting  Limited Partner within 180 days
         of the date the General Partner first received notice of the defaulting
         event.  Upon giving the Notice of Default,  the General Partner,  shall
         have the option to  purchase  at the  Closing  (as  defined  below) the
         Partnership   Interest  of  the  Defaulting   Limited   Partner  (which
         Defaulting  Limited  Partner  shall then become  obligated to sell such
         Partnership Interest) at the price determined in the manner provided in
         Article 18.6 of this Agreement and on the terms and conditions provided
         in Article 18.7 of this  Agreement.  The General  Partner  shall have a
         period of thirty (30) days  following the date of the Notice of Default
         (the  "First  Option  Period")  within  which to notify in writing  the
         Defaulting  Limited  Partner,  whether  the General  Partner  wishes to
         purchase all or a portion of the Partnership Interest of the Defaulting
         Limited Partner. If the General Partner does not elect to purchase the



                                                        -6-


<PAGE>



         entire  Partnership  Interest of the Defaulting  Limited Partner before
         the  expiration of the First Option  Period and in the manner  provided
         herein,  the Limited  Partners shall have the option to purchase all or
         any part of the Partnership  Interest of the Defaulting Limited Partner
         not  purchased by the General  Partner at the price  determined  in the
         manner  provided in Article 18.6 of this Agreement and on the terms and
         conditions  provided  in Article  18.7 of this  Agreement.  Any Limited
         Partner  desiring  to  purchase  any  part  or  all  of  the  remaining
         Partnership Interest of the Defaulting Limited Partner shall deliver to
         the General  Partner a written  election to purchase all or a specified
         portion  of such  Partnership  Interest  within the ten (10) day period
         immediately following the close of the First Option Period (the "Second
         Option  Period").  If the Limited  Partners in the  aggregate  elect to
         purchase  more  than the  Partnership  Interest  then  available,  each
         electing  Limited  Partner  shall have a priority,  up to that  portion
         specified in his or her notice of election, to purchase such proportion
         of the  Partnership  Interest of the  Defaulting  Limited  Partner then
         available  as his or her  Percentage  Interest  bears to the  aggregate
         Percentage Interests of the Limited Partners electing to purchase. That
         portion of the Defaulting  Limited Partner's  Partnership  Interest not
         purchased  on such a priority  basis shall be  allocated in one or more
         successive  allocations to those remaining Limited Partners electing to
         purchase  more of the  Partnership  Interest  than they have a priority
         right, up to the portion  specified in their respective  elections,  in
         the proportion  that each of their  Percentage  Interests  bears to the
         aggregate  Percentage  Interests of all of them. The Valuation Date for
         determining  the  price  paid  for  the  Defaulting  Limited  Partner's
         interest  under  Article  18.6  shall  be the  last  day  of the  month
         immediately   preceding  the  month  in  which  occurs  the  Notice  of
         Withdrawal or breach of Article 15.3.

                           Within the ten (10) day period immediately  following
         the close of the Second Option Period (the "Confirmation  Period"), the
         General  Partner  shall  inform each  electing  Limited  Partner of the
         portion of the Partnership  Interest of the Defaulting  Limited Partner
         as to which his or her election is effective. The General Partner shall
         give notice to the Defaulting  Limited  Partner within the ten (10) day
         period   following   the  close  of  the   Confirmation   Period   (the
         "Notification  Period")  of the  election  by the  Limited  Partners to
         exercise  their option.  Such notice shall  indicate the portion of the
         Defaulting  Limited  Partner's   Partnership   Interest  that  will  be
         purchased by each of the  purchasing  Limited  Partners and the General
         Partner, if any.

                       Confidentiality Provision Amendment

                  Article 15 of the  Partnership  Agreement is hereby amended by
adding a new Article 15.5 as set forth below:

15.5 Disclosure of Confidential  Information.  Each Limited Partner acknowledges
     and agrees that his or her participation in the Partnership under this




                                                        -7-


<PAGE>



         Agreement  necessarily  involves his or her understanding of and access
         to certain trade secrets and other confidential  information pertaining
         to the business of the Partnership.  Accordingly,  each Limited Partner
         (other than the General  Partner and its Affiliates  that may also hold
         Limited Partner  interests)  agrees that at all times during his or her
         participation  in the  Partnership as a Limited Partner and thereafter,
         he or she will not, directly or indirectly, without the express written
         authority of the  Partnership,  unless required by law or directed by a
         applicable  legal  authority  having   jurisdiction  over  the  Limited
         Partner, disclose or use for the benefit of any person,  corporation or
         other entity (other than the Partnership),  or himself or herself,  (i)
         any trade,  technical,  operational,  management or other secrets,  any
         patient or customer lists or other  confidential or secret data, or any
         other   proprietary,   confidential   or  secret   information  of  the
         Partnership or (ii) any confidential  information concerning any of the
         financial  arrangements,  financial  positions,  hospital or  physician
         contracts,  third  party  payor  arrangements,  quality  assurance  and
         outcome analysis  programs,  competitive  status,  customer or supplier
         matters, internal organizational matters, technical abilities, or other
         business  affairs  of or  relating  to  the  Partnership.  The  Limited
         Partners  (other than the General  Partner and its Affiliates  that may
         also  hold  Limited  Partner  interests)  acknowledge  that  all of the
         foregoing constitutes proprietary  information,  which is the exclusive
         property  of the  Partnership.  In the event of breach of this  Article
         15.5 as determined by the General  Partner,  the  Partnership  shall be
         entitled  to any remedy at law or equity with  respect to such  breach,
         including without limitation, an injunction or suit for damages.



                                                        -8-


<PAGE>


                                    EXHIBIT C

                      PURCHASE OPTION ASSIGNMENT AMENDMENT
                       -----------------------------------


                  Capitalized  terms  used in  this  Exhibit  and not  otherwise
defined  shall have the same  meaning as  provided in the  Agreement  of Limited
Partnership (the  "Partnership  Agreement") of San Diego  Lithotripters  Limited
Partnership (the "Partnership").

                      Purchase Option Assignment Amendment

                  Articles 18.1.2,  18.2.2, 18.3.2 and 18.4.2 are hereby amended
to allow the General  Partner to either  exercise  its  purchase  option  rights
during the First Option Period as provided in such  Articles,  or to assign such
purchase  option rights in whole or in part to the  Partnership.  If the General
Partner's  purchase  option rights are assigned to the  Partnership  as provided
herein,  the  Partnership  shall have the right to use  Partnership  revenues to
exercise  such  rights.  Further,  Articles  18.6 and 18.7 are also  amended  by
substituting the Partnership as a buyer to the extent the General Partner elects
to assign to the Partnership  its purchase option rights under Articles  18.1.2,
18.2.2,  18.3.2 and 18.4.2. If the Partnership  acquires a Partnership  Interest
pursuant to the terms of this Amendment, then the General Partner shall have the
authority  to amend  Schedule A to the  Partnership  Agreement  to  reflect  the
deletion  of the  interests  held by the  selling  Limited  Partners  (or  their
successors in interest),  and to reflect the increased  Percentage  Interests of
the remaining Partners resulting from the redemption.




                                                        -9-


<PAGE>



                                  AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
           FAYETTEVILLE LITHOTRIPTERS LIMITED PARTNERSHIP - VIRGINIA I


                  THIS AMENDMENT, effective as of the 1st day of March, 1999, is
entered into by and among Lithotripters,  Inc., a North Carolina corporation and
the General Partner of Fayetteville  Lithotripters Limited  Partnership-Virginia
I, a Virginia limited partnership (the "Partnership"),  and the Limited Partners
of the Partnership.

                                R E C I T A L S:
                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred  to as  the  "Partners,"  are  parties  to  that  certain
Agreement  of  Limited   Partnership  of  Fayetteville   Lithotripters   Limited
Partnership-Virginia I, as amended (the "Agreement").

                  2. Effective as of March 1, 1999, the General  Partner and the
requisite  percentage  of the  Limited  Partners  consented  in  writing  to the
following  amendment  to the  Agreement,  such  amendment  intended to allow the
General Partner the authority to periodically  offer and sell additional limited
partner interests (a "Dilution Offering ") to local investors.

                  NOW,  THEREFORE,  in accordance with Articles 28 and 29 of the
Partnership Agreement and pursuant to the written consent of the General Partner
and the requisite  percentage of the Limited Partners,  the parties hereto agree
as follows:

                           The  Agreement  is  hereby  amended  as set  forth in
                           Exhibit A hereto.

                                             [Signature Page Follows]



                                                        -1-


<PAGE>




                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                           GENERAL PARTNER:

                           LITHOTRIPTERS, INC., a North Carolina
                         corporation and sole general partner of the Partnership

                                    By:_________________________________________
                                 Title:________________________________________



                                                     ALL THE LIMITED PARTNERS OF
                                                     THE PARTNERSHIP WHOSE NAMES
                                                     APPEARED ON SCHEDULE A-2

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                           Joseph Jenkins, M.D.
                                                           Attorney-in-Fact*
- --------
     *Pursuant  to a Power of  Attorney  given by the  Limited  Partners  in the
Agreement.



                                                        -2-


<PAGE>



                                    EXHIBIT A

                           DILUTION OFFERING AMENDMENT

1.                Capitalized  terms  used in  this  Exhibit  and not  otherwise
                  defined shall have the same meaning as provided in the Limited
                  Partnership   Agreement  (the   "Partnership   Agreement")  of
                  Fayetteville Lithotripters Limited Partnership-Virginia I (the
                  "Partnership").

2.   The  purpose of this  Exhibit is to set forth a proposed  amendment  to the
     Partnership  Agreement  that would give the General  Partner the  authority
     periodically  to  offer  and  sell  additional  limited  partner  interests
     ("Dilution Offering") to local Virginia urologists who are not investors in
     the Partnership ("Qualified Investors").  As required by Articles 28 and 29
     of the  Partnership  Agreement,  to be  effective  this  amendment  must be
     approved by the Partners representing two-thirds of the aggregate interests
     in the Partnership.

3.   The purposes of a Dilution Offering are (i) to raise additional capital for
     Partnership  operations,  and (ii) to assure the highest quality of patient
     care by  admitting  Qualified  Investors  to the  Partnership  who  will be
     dedicated  and  motivated as owners to follow the  Partnership's  treatment
     protocol,  and comply  with its  quality  assurance  and  outcome  analysis
     programs.  Any additional  capital raised by the  Partnership in a Dilution
     Offering can be used for any legitimate Partnership purpose,  including (i)
     upgrading the Partnership's Lithostar(TM)Mobile System.

4.                Any sale of limited partner  interests to Qualified  Investors
                  will result in the  proportionate  dilution of the Partnership
                  Percentage  Interests  of the  existing  Partners;  i.e.,  the
                  interests of the General  Partner and the Limited  Partners in
                  Partnership allocations,  cash distributions and voting rights
                  will  be  proportionately  reduced  by a  successful  Dilution
                  Offering.

5.                The Percentage  Interests of the existing  Partners  cannot be
                  diluted  through  Dilution  Offerings  by more than 20% in the
                  aggregate  without the prior written  consent of a Majority in
                  Interest  of  all  the  Partners.   Without   obtaining   this
                  additional consent, the existing Partners cannot be diluted to
                  less than 80% of their  Percentage  Interest  ownership at the
                  time of this Amendment.

6.                The General Partner has determined that the purchase price per
                  1%  Partnership   Interest  offered  in  the  initial  planned
                  Dilution  Offering  will  be  at  its  fair  market  value  as
                  determined by an independent third party appraiser  (Philpott,
                  Ball & Company).  The price for units sold in future  dilution
                  offerings  also must be at a price no less  than  fair  market
                  value as determined by the General Partner.



                                                        -3-


<PAGE>


7.                Upon  the  successful  sale  of  Partnership  Interests  in  a
                  Dilution Offering, the General Partner will prepare and attach
                  a new Schedule A to the  Partnership  Agreement to reflect (i)
                  the   Partners'   adjusted   Percentage   Interests   in   the
                  Partnership,  and  (ii)  the  admission  of  the  new  Limited
                  Partners to the Partnership.



                                                        -4-


<PAGE>



                               FOURTH AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
       FAYETTEVILLE LITHOTRIPTERS LIMITED PARTNERSHIP - SOUTH CAROLINA II


                  THIS AMENDMENT, effective as of the 1st day of April, 1999, is
entered into by and among Lithotripters,  Inc., a North Carolina corporation and
the General  Partner of  Fayetteville  Lithotripters  Limited  Partnership-South
Carolina II, a South Carolina limited partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.

                                R E C I T A L S:
                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred  to as  the  "Partners,"  are  parties  to  that  certain
Agreement  of  Limited   Partnership  of  Fayetteville   Lithotripters   Limited
Partnership-South Carolina II, as amended (the "Agreement").

                  2. Effective as of April 1, 1999, the General  Partner and the
requisite  percentage  of the  Limited  Partners  consented  in  writing  to the
following  amendments to the Agreement,  such amendments  intended to: (i) allow
the General  Partner the  authority to  periodically  offer and sell  additional
limited  partner  interests (a "Dilution  Offering") to local South Carolina and
North  Carolina   investors;(ii)   clarify  and  strengthen  the  noncompetition
provisions of Articles 15.3 and 18.4 of the Agreement; (iii) add a new provision
to  the  Agreement  to  prevent  the  disclosure  of  Confidential   Partnership
Information  that might harm the  Partnership  and its Partners;  (iv) allow the
General Partner,  in its sole discretion,  to elect to assign to the Partnership
its rights  under  Article  18 of the  Agreement  to  purchase  the  Partnership
Interest of any deceased,  insolvent or competing Limited Partner; and (v) allow
the General  Partner or the  Partnership,  as the case may be, to  purchase  the
Partnership  Interest of any  deceased  Limited  Partner at a price equal to the
greater of (a) Capital Account value or (b) 1.5 times the aggregate distribution
amount  attributable to such interest  during the twelve month period  preceding
the death of the Limited Partner.

                  NOW,  THEREFORE,  in accordance with Articles 29 and 30 of the
Partnership Agreement and pursuant to the written consent of the General Partner
and the requisite  percentage of the Limited Partners,  the parties hereto agree
as follows:

                           The  Agreement  is  hereby  amended  as set  forth in
                           Exhibits A, B, C and D attached hereto.



                                                        -1-


<PAGE>




                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                          GENERAL PARTNER:

                          LITHOTRIPTERS, INC., a North Carolina corporation and
                            sole general partner of the Partnership

                               By:_________________________________________
                               Title:________________________________________



                                                 ALL THE LIMITED PARTNERS OF
                                                 THE PARTNERSHIP WHOSE NAMES
                                                 APPEARED ON SCHEDULE A-3

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                     Joseph Jenkins, M.D.
                                                     Attorney-in-Fact*
- --------
     *Pursuant  to a Power of  Attorney  given by the  Limited  Partners  in the
Agreement.

                                                        -2-


<PAGE>




                                    EXHIBIT A

                           DILUTION OFFERING AMENDMENT

1. Capitalized  terms used in this Exhibit and not otherwise  defined shall have
the same  meaning as  provided  in the  Agreement  of Limited  Partnership  (the
"Partnership  Agreement") of Fayetteville  Lithotripters  Limited  Partnership -
South Carolina II (the "Partnership"), and any amendments thereto.

2. The  purpose  of this  Exhibit is to set forth a  proposed  amendment  to the
Partnership  Agreement  that  would  give  the  General  Partner  the  authority
periodically to offer and sell additional limited partner interests (a "Dilution
Offering") to local South  Carolina and North  Carolina  urologists  who are not
investors in the Partnership ("Qualified Investors").  As required by Article 30
of the Partnership Agreement, to be effective this amendment must be approved by
the  Partners  representing   two-thirds  of  the  aggregate  interests  in  the
Partnership.

3. The purposes of a Dilution  Offering are (i) to raise additional  capital for
any valid Partnership purpose, and (ii) to assure the highest quality of patient
care by admitting  Qualified  Investors to the Partnership who will be dedicated
and  motivated as owners to follow the  Partnership's  treatment  protocol,  and
comply with its quality assurance and outcome analysis programs.  Any additional
capital  raised by the  Partnership  in a Dilution  Offering can be used for any
legitimate   Partnership   purpose,   including   upgrading  the   Partnership's
Lithostar(TM) Mobile Systems.

4. Any sale of limited partner  interests to Qualified  Investors will result in
the  proportionate  dilution  of the  Partnership  Percentage  Interests  of the
existing  Partners;  i.e., the interests of the General  Partner and the Limited
Partners in Partnership  allocations,  cash distributions and voting rights will
be proportionately reduced by a successful Dilution Offering.

5. The Percentage  Interests of the existing  Partners cannot be diluted through
Dilution  Offerings by more than 20% in the aggregate  without the prior written
consent of a Majority in Interest of all the Partners.  Without  obtaining  this
additional consent,  the existing Partners cannot be diluted to less than 80% of
their Percentage Interest ownership at the time of this Amendment.

6. The General Partner has determined that the purchase price per 1% Partnership
Interest  offered in the initial planned  Dilution  Offering will be at its fair
market value as determined by an independent  third party  appraiser.  The price
for Units sold in future dilution offerings also must be at a price no less than
fair market value as determined by the General Partner.

7. Upon the successful sale of Partnership Interests in a Dilution Offering, the
General  Partner  will  prepare and attach a new  Schedule A to the  Partnership
Agreement  to reflect (i) the  Partners'  adjusted  Percentage  Interests in the
Partnership,  and  (ii)  the  admission  of  the  new  Limited  Partners  to the
Partnership.



                                                        -3-


<PAGE>



                                    EXHIBIT B

                       NONCOMPETITION PROVISION AMENDMENT

                  Capitalized  terms  used in  this  Exhibit  and not  otherwise
defined  shall have the same  meaning as  provided in the  Agreement  of Limited
Partnership (the "Partnership Agreement") of Fayetteville  Lithotripters Limited
Partnership - South Carolina II (the "Partnership"), and any amendments thereto.

                       Noncompetition Provision Amendment

                  Article 15.3 of the Partnership Agreement is hereby amended by
deleting the current  provision in its entirety and by substituting the language
set forth below:

                  15.3 Outside Activities.  The Limited Partners agree that they
         owe fiduciary  duties to the  Partnership  and, as a consequence,  each
         Limited Partner (that is not the General Partner or an Affiliate of the
         General  Partner)  agrees  that he or she shall not engage in  "Outside
         Activities"  (as defined below) in the "Market Area" (as defined below)
         while he or she is a Limited  Partner  in the  Partnership.  The phrase
         "Outside  Activities" means directly or indirectly  owning,  leasing or
         subleasing  a  lithotripter  (or any  similar  equipment  or  competing
         devices used for treating renal or biliary stone  disease).  Prohibited
         indirect  ownership  shall include the direct or indirect  ownership of
         any  interest  in  a  business   venture   (through  stock   ownership,
         partnership interest ownership,  ownership by or through a close family
         member,  or as  otherwise  determined  in  good  faith  by the  General
         Partner) involving the ownership, purchase, lease, sublease, promotion,
         management  or operation  of a  lithotripter  (or similar  equipment or
         competing  devices used for treating  renal or biliary stone  disease),
         unless the General Partner determines that such activity by the Limited
         Partners is not detrimental to the best interests of the Partnership.

                           Upon  the   termination  or  transfer  of  a  Limited
         Partner's  interest  in the  Partnership  for any  reason,  including a
         transfer  pursuant to Article  18.4  hereof,  the  withdrawing  Limited
         Partner shall not, for a period of two (2) years  following the date of
         his or her withdrawal,  engage in any Outside Activities in any "Market
         Area" in which the  Partnership is  transacting  business or within the
         prior  twelve  months  has   transacted   business   (the   "Restricted
         Facilities").  For the purposes of this Article 15.3,  the term "Market
         Area"  shall  mean  (i)  the  area  within  a ten  mile  radius  of any
         Restricted  Facility,  but if such  area is  determined  by a court  of
         competent  jurisdiction  to be too  broad,  then it shall mean (ii) the
         area within a five mile radius of any Restricted Facility,  but if such
         area is determined by a court of competent jurisdiction to be too broad
         then it shall  mean  (iii)  the area  within a two mile  radius  of any
         Restricted Facility.



                                                        -4-


<PAGE>



                           In the event a Limited  Partner wishes and intends to
         engage in an Outside  Activity in a Market Area, he or she must provide
         written notice of such intent to the General  Partner prior to engaging
         in the Outside Activity. The written notice shall be deemed an election
         by the Limited Partner to withdraw from the Partnership (the "Notice of
         Withdrawal"),  and shall give the  General  Partner  and/or the Limited
         Partners the purchase rights as provided in Article 18.4 hereof.  After
         the Notice of Withdrawal,  the former Limited  Partner may engage in an
         Outside  Activity in the Market  Area only after  waiting the period of
         two years specified in this Article 15.3. In the event of breach of the
         waiting period,  the partnership shall be entitled to any remedy at law
         or equity with respect to such breach,  including without limitation an
         injunction or suit for damages.

                           If a Limited Partner during his or her  participation
         in the  Partnership  engages in an Outside  Activity  in a Market  Area
         without  first  notifying  the  General  Partner in  violation  of this
         Article  15.3,  the  Limited  Partner  shall be deemed to have  given a
         Notice of  Withdrawal  on the date the General  Partner  first  becomes
         aware of the Limited  Partner's  Outside  Activity in the Market  Area.
         Upon receiving a Limited  Partner's  Notice of Withdrawal or equivalent
         thereof,  the General  Partner and/or  Limited  Partners may invoke the
         purchase  rights  provided in Article 18.4 and shall be entitled to any
         other  remedy  at law or in  equity  including  without  limitation  an
         injunction or suit for damages.

                  Article 18.4 of the Partnership Agreement is hereby amended by
deleting the current  provision in its entirety and by substituting the language
set forth below.

                           18.4 Breach of Article 15.3. In the event the General
         Partner  either  receives a Notice of Withdrawal as provided in Article
         15.3 or  receives  notice  of a breach  of  Article  15.3 by a  Limited
         Partner (the  "Defaulting  Limited  Partner"),  the General Partner may
         elect, in its sole  discretion,  to treat such event as a default under
         this  Agreement and enforce the provisions of this Article 18.4. If the
         General  Partner elects to enforce the provisions of this Article 18.4,
         the General  Partner  shall give written  notice of such  election (the
         "Notice of Default") to the Defaulting  Limited Partner within 180 days
         of the date the General Partner first received notice of the defaulting
         event.  Upon giving the Notice of Default,  the General Partner,  shall
         have the option to  purchase  at the  Closing  (as  defined  below) the
         Partnership   Interest  of  the  Defaulting   Limited   Partner  (which
         Defaulting  Limited  Partner  shall then become  obligated to sell such
         Partnership Interest) at the price determined in the manner provided in
         Article 18.6 of this Agreement and on the terms and conditions provided
         in Article 18.7 of this  Agreement.  The General  Partner  shall have a
         period of thirty (30) days  following the date of the Notice of Default
         (the  "First  Option  Period")  within  which to notify in writing  the
         Defaulting  Limited  Partner,  whether  the General  Partner  wishes to
         purchase all or a portion of the Partnership Interest of the Defaulting
         Limited Partner. If the General Partner does not elect to purchase the



                                                        -5-


<PAGE>



         entire  Partnership  Interest of the Defaulting  Limited Partner before
         the  expiration of the First Option  Period and in the manner  provided
         herein,  the Limited  Partners shall have the option to purchase all or
         any part of the Partnership  Interest of the Defaulting Limited Partner
         not  purchased by the General  Partner at the price  determined  in the
         manner  provided in Article 18.6 of this Agreement and on the terms and
         conditions  provided  in Article  18.7 of this  Agreement.  Any Limited
         Partner  desiring  to  purchase  any  part  or  all  of  the  remaining
         Partnership Interest of the Defaulting Limited Partner shall deliver to
         the General  Partner a written  election to purchase all or a specified
         portion  of such  Partnership  Interest  within the ten (10) day period
         immediately following the close of the First Option Period (the "Second
         Option  Period").  If the Limited  Partners in the  aggregate  elect to
         purchase  more  than the  Partnership  Interest  then  available,  each
         electing  Limited  Partner  shall have a priority,  up to that  portion
         specified in his or her notice of election, to purchase such proportion
         of the  Partnership  Interest of the  Defaulting  Limited  Partner then
         available  as his or her  Percentage  Interest  bears to the  aggregate
         Percentage Interests of the Limited Partners electing to purchase. That
         portion of the Defaulting  Limited Partner's  Partnership  Interest not
         purchased  on such a priority  basis shall be  allocated in one or more
         successive  allocations to those remaining Limited Partners electing to
         purchase  more of the  Partnership  Interest  than they have a priority
         right, up to the portion  specified in their respective  elections,  in
         the proportion  that each of their  Percentage  Interests  bears to the
         aggregate  Percentage  Interests of all of them. the Valuation Date for
         determining  the  price  paid  for  the  Defaulting  Limited  Partner's
         interest  under  Article  18.6  shall  be the  last  day  of the  month
         immediately   preceding  the  month  in  which  occurs  the  Notice  of
         Withdrawal or breach of Article 15.3.

                           Within the ten (10) day period immediately  following
         the close of the Second Option Period (the "Confirmation  Period"), the
         General  Partner  shall  inform each  electing  Limited  Partner of the
         portion of the Partnership  Interest of the Defaulting  Limited Partner
         of the portion of the  Partnership  Interest of the Defaulting  Limited
         Partner  as to which his or her  election  is  effective.  The  General
         Partner shall give notice to the Defaulting  Limited Partner within the
         ten (10) day period following the close of the Confirmation Period (the
         "Notification  Period")  of the  election  by the  Limited  Partners to
         exercise  their option.  Such notice shall  indicate the portion of the
         Defaulting  Limited  Partner's   Partnership   Interest  that  will  be
         purchased by each of the  purchasing  Limited  Partners and the General
         Partner, if any.



                                                        -6-


<PAGE>



                       Confidentiality Provision Amendment

                  Article 15 of the  Partnership  Agreement is hereby amended by
adding a new Article 15.4 as set forth below:

                           15.4  Disclosure of  Confidential  Information.  Each
         Limited Partner  acknowledges and agrees that his or her  participation
         in the Partnership under this Agreement necessarily involves his or her
         understanding  of  and  access  to  certain  trade  secrets  and  other
         confidential information pertaining to the business of the Partnership.
         Accordingly,  each Limited  Partner (other than the General Partner and
         its Affiliates  that may also hold Limited  Partner  interests)  agrees
         that at all times during his or her participation in the Partnership as
         a Limited  Partner  and  thereafter,  he or she will not,  directly  or
         indirectly,  without the express written  authority of the Partnership,
         unless  required  by law or directed by a  applicable  legal  authority
         having  jurisdiction over the Limited Partner,  disclose or use for the
         benefit of any  person,  corporation  or other  entity  (other than the
         Partnership),   or  himself  or  herself,  (i)  any  trade,  technical,
         operational, management or other secrets, any patient or customer lists
         or  other  confidential  or  secret  data,  or any  other  proprietary,
         confidential  or  secret  information  of the  Partnership  or (ii) any
         confidential  information concerning any of the financial arrangements,
         financial positions, hospital or physician contracts, third party payor
         arrangements,   quality   assurance  and  outcome  analysis   programs,
         competitive   status,   customer   or   supplier   matters,    internal
         organizational matters,  technical abilities, or other business affairs
         of or relating to the Partnership. The Limited Partners (other than the
         General  Partner and its Affiliates  that may also hold Limited Partner
         interests)   acknowledge   that  all  of  the   foregoing   constitutes
         proprietary  information,  which  is  the  exclusive  property  of  the
         Partnership.  In the event of breach of this Article 15.4 as determined
         by the General Partner, the Partnership shall be entitled to any remedy
         at law or in equity  with  respect to such  breach,  including  without
         limitation, an injunction or suit for damages.



                                                        -7-


<PAGE>



                                    EXHIBIT C

                      PURCHASE OPTION ASSIGNMENT AMENDMENT

                  Capitalized  terms  used in  this  Exhibit  and not  otherwise
defined  shall have the same  meaning as  provided in the  Agreement  of Limited
Partnership (the "Partnership Agreement") of Fayetteville  Lithotripters Limited
Partnership - South Carolina II (the "Partnership").

                      Purchase Option Assignment Amendment

                  Articles 18.1.2,  18.2.2, 18.3.2 and 18.4.2 are hereby amended
to allow the General  Partner to either  exercise  its  purchase  option  rights
during the First Option Period as provided in such  Articles,  or to assign such
purchase  option rights in whole or in part to the  Partnership.  If the General
Partner's  purchase  option rights are assigned to the  Partnership  as provided
herein,  the  Partnership  shall have the right to use  Partnership  revenues to
exercise  such  rights.  Further,  Articles  18.6 and 18.7 are also  amended  by
substituting the Partnership as a buyer to the extent the General Partner elects
to assign to the Partnership  its purchase option rights under Articles  18.1.2,
18.2.2,  18.3.2 and 18.4.2. If the Partnership  acquires a Partnership  Interest
pursuant to the terms of this Amendment, then the General Partner shall have the
authority  to amend  Schedule A to the  Partnership  Agreement  to  reflect  the
deletion  of the  interests  held by the  selling  Limited  Partners  (or  their
successors in interest),  and to reflect the increased  Percentage  Interests of
the remaining Partners resulting from the redemption.



                                                        -8-


<PAGE>


                                    EXHIBIT D

                         DEATH PURCHASE PRICE AMENDMENT

                           Capitalized  terms  used  in  this  Exhibit  and  not
         otherwise  defined  shall  have the same  meaning  as  provided  in the
         Agreement  of Limited  Partnership  (the  "Partnership  Agreement")  of
         Fayetteville Lithotripters Limited Partnership - South Carolina II (the
         "Partnership").

                         Death Purchase Price Amendment

                           Article  18.6 is hereby  amended to allow the General
         Partner (or in the event the Purchase  Option  Assignment  Amendment is
         approved,  the  Partnership  as  the  General  Partner's  Assignee)  to
         purchase the  Partnership  Interest of a deceased  Limited Partner upon
         exercise of the purchase  option right  granted to the General  Partner
         (or its assignee, the Partnership) during the First Option Period under
         Article  18.1.2,  for a price equal to the greater of (i) the  deceased
         Limited Partner's share of the  Partnership's  book value determined in
         the manner  described in Article  18.6, or (ii) 1.5 times the aggregate
         distribution   attributable   to  such   deceased   Limited   Partner's
         Partnership Interest for the twelve-month period immediately  preceding
         the  Valuation  Date.  At the  Closing  of the sale of the  Partnership
         Interest of a deceased  Limited  Partner,  although  not  necessary  to
         effect the  transfer,  the executor or personal  representative  of the
         deceased Limited  Partner's estate shall,  concurrently with tender and
         receipt of the purchase  price,  deliver to the General  Partner,  duly
         executed  instruments  of transfer and  assignment  assigning  good and
         marketable title to the deceased Limited  Partner's entire  Partnership
         Interest,  free and clear from any liens or  encumbrances  or rights of
         others therein.  The deemed transfer is effective regardless of whether
         the  executor  or  personal  representative  of  the  deceased  Limited
         Partner's estate performs the duties set forth herein.  Notwithstanding
         the date of the Closing, or whether a Closing is successfully held, the
         transfer of a Partnership  Interest of a deceased Limited Partner shall
         be deemed to occur as of the  Valuation  Date.  Further,  in connection
         with the foregoing,  Articles 14 and 17.3 are amended to provide that a
         transferee  of a deceased  Limited  Partner who  receives  such Limited
         Partner's  Partnership  Interest by operation of law or otherwise shall
         have no right to receive any distributions attributable to such Limited
         Partner's  Partnership  Interest after the Valuation  Date,  unless the
         General Partner  consents to the same. The  Partnership  shall have the
         right to deduct  from the  purchase  price  payable  for such  deceased
         Limited Partner's  Partnership Interest the amount of any distributions
         made to the estate of the deceased  Limited Partner after the Valuation
         Date.



                                                        -9-


<PAGE>
                               FIFTH AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
       FAYETTEVILLE LITHOTRIPTERS LIMITED PARTNERSHIP - SOUTH CAROLINA II


                  THIS AMENDMENT, effective as of the 1st day of August 1999, is
entered into by and among Lithotripters,  Inc., a North Carolina corporation and
the General Partner of Fayetteville  Lithotripters  Limited  Partnership - South
Carolina II, a South Carolina limited partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.

                                                 R E C I T A L S:
                                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred  to as  the  "Partners,"  are  parties  to  that  certain
Agreement  of  Limited   Partnership  of  Fayetteville   Lithotripters   Limited
Partnership - South  Carolina II, dated  effective as of March 17, 1989,  and as
subsequently amended (the "Agreement").

     2. The  Partners  desire to further  amend the  Agreement  to  reflect  the
assignment  of  an  aggregate  of  a  2.67%  limited  partner  interest  in  the
Partnership,  respectively,  from Harry W. Kinard, M.D. and Clifton L. Williams,
M.D. to the following individuals: Peter Parramoure, M.D. (.78%); Jim Lugg, J.D.
(.78%); Thomas E. Hamilton, M.D. (.78%); William F. Flanagan, M.D. (.78%); Roger
G. McAlpine,  M.D. (.37);  Preston Turner,  M.D. (.29%);  J. Ronald Smith,  M.D.
(.78%); and J. Robert Monroe, M.D. (.78%), (collectively,  the "Assignees"), and
the admission of the Assignees as substitute Limited Partners.

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A-3 is  deleted in its  entirety  and a new
                           Schedule A-4,  attached hereto, is substituted in its
                           place.

                                             [Signature Page Follows}





                                                        -1-


<PAGE>



                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                                                  GENERAL PARTNER:

                                                  Lithotripters, Inc.


                                       By:

                                              Name:____________________________
                                            Title:_____________________________


                                                  ALL THE LIMITED PARTNERS OF
                                                  THE PARTNERSHIP WHOSE NAMES
                                                  APPEARED ON SCHEDULE A-3

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------

                                                      Joseph Jenkins, M.D.
                                                      Attorney-in-Fact*

- --------
     *Pursuant  to a Power of  Attorney  given by the  Limited  Partners  in the
Agreement.



                                                        -2-


<PAGE>

                                                                    SCHEDULE A-4


                        Schedule of Partnership Interests

        FAYETTEVILLE LITHOTRIPTERS LIMITED PARTNERSHIP-SOUTH CAROLINA II

      CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND PERCENTAGE INTERESTS

                                   Cash                    Percentage
General Partner                Contribution(1)              Interest
- ---------------                 ------------                --------


Lithotripters, Inc.              $ 19,375                    20.00%
2008 Litho Place, Suite 201
Fayetteville, NC 28304

Limited Partners

Charlton P. Armstrong III           4,000                     4.00%
52 Bear Drive
Greenville, SC 29605

H. Sykes Dehart                     2,750                     3.00%
11 Park Creek Drive
Greenville, SC 29605

R. Douglas DeVore                   2,000                     2.00%
310 Memorial Drive
Greer, SC 29650

Dean M. Dobson                      2,000                     2.00%
Post Office Box 427
Seneca, SC 29679

John S. Evans                       2,000                     2.00%
11 Park Creek Drive
Greenville, SC 29605

William F. Flanagan                 N/A (3)                    .78%

Lawrence Hill                       2,000                     2.00%
527 Mills Avenue
Greenville, SC 29605




                                                        -3-


<PAGE>


                                   Cash                      Percentage
Limited Partners               Contribution                   Interest

Thomas E. Hamilton                  N/A (3)                    .78%

Thomas H. Jordan                    1,125                     1.00%
644 S. Third Street, WC 244
Louisville, KY 40202-2465

David M. Kraebber, M.D.             2,000                     1.33%
404 West 8th Street
Hendersonville, NC 28739

J. Ernest Lathem                    4,000                     4.00%
527 Mills Avenue
Greenville, SC 29605

Lithotripters, Inc.                 N/A(2)                   12.33%
2008 Litho Place, Suite 201
Fayetteville, NC 28304

Woodrow W. Long, Jr.                4,000                     4.00%
18 Memorial Medical Drive
Greenville, SC 29605

Jim Lugg                            N/A (3)                    .78%

R. James McNaughton, Jr.            2,000                     2.00%
317 S. Francis Drive
Suite 210
Greenville, SC 29348

Michael S. Mathers                  4,000                     4.00%
52 Bear Drive
Greenville, SC 29605

Roger G. McAlpine                   N/A (3)                    .37%

Roy M. McCoy                        4,000                     4.00%
527 Mills Avenue
Greenville, SC 29605

J. Robert Monroe                    N/A (3)                   .78%






                                                        -4-


<PAGE>


                                   Cash                      Percentage
Limited Partners               Contribution                   Interest

Arnold P. Mulkey                    4,000                     4.00%
Greenwood Medical Center
Greenwood, SC 29646

Peter Parramoure                    N/A (3)                    .78%

James D. Rice                       2,000                     2.00%
52 Bear Drive
Greenville, SC 29605

J. Ronald Smith                     N/A (3)                    .78%

Colin B. Thomas                     3,000                     2.00%
512 6th Avenue
Hendersonville, NC 28739

Michael D. Turner                   4,000                     4.00%
Greenwood Medical Center
Greenwood, SC 29646

Preston Turner                      N/A (3)                    .29%

Donald R. Vaughn, M.D.              4,000                     4.00%
18 Memorial Drive Extension
Greer, SC 29650

John E. Walton                      4,000                     4.00%
400 Memorial Drive Extension
Greer, SC 29650

Linton B. West, M.D.                2,750                     3.00%
11 Park Creek Drive
Greenville, SC 29605

Norris W. Whitlock                  2,000                     2.00%
310 Memorial Drive
Greer, SC 29650







                                                        -5-


<PAGE>


                                     Cash                      Percentage
Limited Partners                  Contribution                  Interest

David Randall Williams, M.D.        3,000                        2.00%
512 6th Avenue
Hendersonville, NC 28739
                                  ---------                    ---------

          TOTAL                  $ 92,000                        100%






(1)       The cash  contributions  listed reflect the initial  contributions  of
          those Partners who currently hold an interest in the Partnership.

     (2)  Lithotripters,  Inc. received its limited partner interest pursuant to
various assignments from existing limited partners and, therefore,  made no cash
contributions to the Partnership.

     (3)  Received  their  limited   partner   interests   pursuant  to  various
assignments from existing limited partners as of August 1, 1999 and,  therefore,
made no cash contributions to the Partnership.











                                                        -6-


<PAGE>



                                  AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
             FAYETTEVILLE LITHOTRIPTERS LIMITED PARTNERSHIP - UTAH I


                  THIS AMENDMENT,  effective as of the 1st day of June, 1999, is
entered into by and among Lithotripters,  Inc., a North Carolina corporation and
the General Partner of Fayetteville  Lithotripters Limited Partnership-Utah I, a
Utah limited  partnership (the  "Partnership"),  and the Limited Partners of the
Partnership.

                                R E C I T A L S:
                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the "Partners," are parties to that certain Amended
and Restated  Agreement of Limited  Partnership  of  Fayetteville  Lithotripters
Limited  Partnership-Utah  I,  dated  as of  January  7,  1989 as  amended  (the
"Agreement").

                  2. The  Partners  desire to  further  amend the  Agreement  to
reflect the redemption by the  Partnership of an aggregate 1.5% limited  partner
interest from Stacy Childs, M.D.

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A-6 is  deleted in its  entirety  and a new
                           Schedule A-7,  attached  hereto is substituted in its
                           place.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                                       GENERAL PARTNER:

                                       LITHOTRIPTERS, INC.


                                  By:/s/ Joseph Jenkins, M.D.
                                  --------------------------
                                            Joseph Jenkins, M.D.
                                            President



                                                        -1-


<PAGE>





                                        ALL THE LIMITED PARTNERS OF
                                        THE PARTNERSHIP WHOSE NAMES
                                        APPEARED ON SCHEDULE A-6

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                      Joseph Jenkins, M.D.
                                                      Attorney-in-Fact*
- --------
     *Pursuant  to a Power of  Attorney  given by the  Limited  Partners  in the
Agreement.



                                                        -2-


<PAGE>



                                  SCHEDULE A-7


                        Schedule of Partnership Interests

              FAYETTEVILLE LITHOTRIPTERS LIMITED PARTNERSHIP-UTAH I

      CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND PERCENTAGE INTERESTS

                                       Cash                   Percentage
General Partner                     Contribution (1)           Interest
- ------- -------                     ------------               --------

Lithotripters, Inc.                $    19,562.50            19.644670%
2008 Litho Place, Suite 201
Fayetteville, NC  28304

Limited Partners

Joseph Armstrong, M.D.             $ 2,000.00                 1.964467%
1055 North 300 West #303
Provo, UT 84604

Michael J. Bateman                   2,000.00                 1.964467%
Medical Arts Building
1448 East Center, #7
Pocatello, ID 83201

Hal H. Bourne, M.D.                  4,000.00                 2.913706%
324 Tenth Avenue, #178
Salt Lake City, UT 84103

Thomas W. Brady, M.D.                  400.00                  .261929%

Dean L. Bristow, M.D.                2,000.00                 1.964467%
50 South Medical Drive
Payson, UT 84651

Curtis Campbell, M.D.                2,000.00                 1.964467%
3905 Harrison Boulevard
Ogden, UT 84403





                                                        -3-


<PAGE>



Peter M. Cannon, M.D.                3,000.00                    2.947208%
Teton Medical Specialty Center
2001 South Woodruff, Suite 4
Idaho Falls, ID 83404-6370

S. Corbin Clark, M.D.                2,000.00                    1.964467%
9690 South 1300 East, #100
Sandy, UT 84070

Paul K. Clark, M.D.                  2,000.00                    1.964467%
508 East South Temple
Suite 100
Salt Lake City, UT 84102

Robert C. Clift, M.D.                  400.00                     .392893%

Cottage Creek, L.L.C.                  N/A (3)                   1.015228%

Ronald H. Crouch, M.D.               4,000.00                    2.619289%
515 South 300 East
St. George, UT 84770

Duane E. Davis, M.D.                 2,000.00                     .982234%
930 North Fifth West
Provo, UT 84601

Danielle Davis Trust                   N/A (3)                    .982234%

Jonathan Garey-Sage, M.D.              400.00                     .392893%

David Henderson, M.D.                2,000.00                    1.964467%
415 Medical Drive, #202A
Bountiful, UT 84010

James C. Jensen, M.D.               52,500.00                     .761421%

Thomas H. Jordan                       750.00                     .491371%
82 Highwood Street
Louisville, KY 40206

David Kimball, M.D.                  4,000.00                    3.928934%
5770 South 250 East, #305
Salt Lake City, UT 84107





                                                        -4-


<PAGE>



Kenneth Kofoed, M.D.                 2,000.00                    1.964467%
2084 North 1700 West
Layton, UT 84041

Richard E. Lee, M.D.                 2,000.00                    1.964467%
324 Tenth Avenue, #178
Salt Lake City, UT 84103

Lithotripters, Inc.                  4,000.00(2)                15.28934%
2008 Litho Place
Fayetteville, NC 28304

Ned L. Mangelson, M.D.               2,000.00                    1.964467%
333 South Ninth East
Salt Lake City, UT 84102

Michael McFadden, M.D.              35,000.00                     .507614%

Richard B. Melzer, M.D.              1,000.00                     .654822%
2825-8th Avenue North
Billings, MT 59101

Anthony W. Middleton, Jr., M.D.      2,000.00                    1.964467%
1060 East First South, #112
Salt Lake City, UT 84102

George W. Middleton, M.D.            2,000.00                    1.964467%
1060 East First South, #112
Salt Lake City, UT 84102

James F. Morrell, M.D.               2,000.00                    1.964467%
1220 East 3900 South
Salt Lake City, UT 84124

Steven L. Moss, M.D.                   400.00                     .261929%

Ronald I. Oldroyd, M.D.              3,000.00                    1.964467%
930 North 500 West
Provo, UT 84601

Stephen Richardson, M.D.             2,000.00                    1.309645%
3980 South 700 East, #20
Murray, UT 84107
                                     - 5 -
<PAGE>


Odell F. Rigby, M.D.                 4,000.00                    3.928934%
333 South Ninth East
Salt Lake City, UT 84102



Ronald J. Saunders, M.D.             2,000.00                    1.964467%
120 North, 1220 East
American fork, UT 84003

John G. Scott, M.D.                    400.00                     .261929%

Herbert B. Spencer, M.D.             2,000.00                    1.964467%
920 North Fifth West
Provo, UT 84601

Charles T. Swallow, M.D.             2,000.00                    1.309645%
225 East Fourth North
Logan, UT 84321

Roger H. Tall, M.D.                  4,000.00                    3.928934%
Teton Medical Specialty Center
2001 South Woodruff, Suite 8
Idaho Falls, ID 83404-6370

Timothy Taylor, M.D.                35,000.00                     .507614%

Perry T. Walters, M.D.               2,000.00                    1.964467%
425 Medical Drive
Bountiful, UT 84010

Vanez B. Wilson, M.D.                2,000.00                    1.309645%
3980 South 700 East, #20
Murray, UT 84107
                                  --------------                 -------

             TOTAL                $320,812.50                     100%


(1)      The cash contributions  reflect the initial cash contributions of those
         Partners who currently hold an interest in the Partnership.

(2)  Lithotripters,  Inc.  acquired a portion of its  limited  partner  interest
pursuant to various  assignments from existing limited partners and made no cash
contributions to the Partnership for the limited partner interests received as a
result of such assignments.





                                                        -6-


<PAGE>


(3)      Acquired  its limited  partner  interest  pursuant to  assignment  from
         existing  limited  partner  and  made  no  cash  contributions  to  the
         Partnership  for the limited partner  interest  received as a result of
         such assignment.



                                                        -7-


<PAGE>



                               THIRD AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                   FLORIDA LITHOTRIPTERS LIMITED PARTNERSHIP I

                  THIS  AMENDMENT,  effective  as of the 30th day of  September,
1999,  is  entered  into by and  among  Lithotripters,  Inc.,  a North  Carolina
corporation and the General Partner of Florida Lithotripters Limited Partnership
I, a Florida limited partnership (the  "Partnership"),  and the Limited Partners
of the Partnership.

                                    RECITALS:
                                    --------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively referred to as the "Partners",  entered into that certain Agreement
of Limited  Partnership  of Florida  Lithotripters  Limited  Partnership I dated
August 5, 1991, as amended.

     2. The Partners  desire to amend the Agreement to reflect the assignment by
D. Russell Locke and Ira W. Klimberg of their  respective  1.95% limited partner
interests  in the  Partnership  to  Lithotripters,  Inc.,  and the  admission of
Lithotripters, Inc. as a substitute Limited Partner.

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A-3 is  deleted  in its  entirety  and  new
                  Schedule A-4, attached hereto, is substituted in its place.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first-above written.

                                         GENERAL PARTNER:

                                         Lithotripters, Inc.

                                         By:
                                                Name:
                                                Title:

                                        ALL THE LIMITED PARTNERS OF THE
                                        PARTNERSHIP WHOSE NAMES APPEAR ON
                                        SCHEDULE A-3

                                         By:/s/ Joseph Jenkins, M.D.      (SEAL)
                                         ---------------------------
                                                Joseph Jenkins, M.D.,
                                                Attorney-in-Fact*

*  Pursuant  to a  Power  of  Attorney  given  by the  Limited  Partners  in the
Agreement.

                                                      -1-




<PAGE>



                                                                    SCHEDULE A-4

                        Schedule of Partnership Interests

                   Florida Lithotripters Limited Partnership I

           CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND GUARANTIES

                                Cash            Percentage
General Partner         Contribution            Interest

Lithotripters, Inc.       $49,687.52             20.0000

Limited Partners

John P. Adams               2,500.00              1.0000

Stephen W. Alcorn           2,500.00              1.0000

Thomas Ayers                2,500.00              1.0000

Dan Beraha                  4,875.00              1.9500

Jim Brady                     936.68              0.4163

B. Thomas Brown             4,500.00              1.8000

Joseph L. Camps             3,250.00              1.3000

Anthony L. Cantwell         2,500.00              1.0000

Charles Cartwright          2,500.00              1.0000

Ramesh Chopra               2,500.00              1.0000

Franklin Clark                937.58              0.4167

Mark Cohen                  2,500.00              1.0000

J. A. Colom                 3,250.00              1.3000

David Cunningham            4,125.00              1.6500

Allan Davis                 2,500.00              1.0000

Stephen L. Deardourff       2,500.00              1.0000

Fran Deture                 N/A (1)               1.0000

Pareshkumar Desai           4,875.00              1.9500

Martin K. Dineen            4,125.00              1.6500

Neil P. Dunn                2,500.00              1.0000

Basil Fossum                2,500.00              1.0000

Clark Gaddy                 2,500.00              1.0000

Philip Gallina                937.58              0.4167

John Garner                 2,500.00              1.0000

Michael Grable              4,125.00              1.6500

Frank Greskovich            2,500.00              1.0000

William Grine                 937.58              0.4167



<PAGE>


                                Cash            Percentage
General Partner         Contribution            Interest



Lawrence Hatchattq          $2,500.00            1.0000%

Dennis Healey                N/A (2)             0.6500

Warren T. Hitt              3,250.00             1.3000

Joseph Jenkins                937.58             0.4167

William Jones               2,500.00             1.0000

Thomas Jordan                 937.58             0.4167

William Jordan                937.58             0.4167

Charles King                4,875.00             1.9500

Robert Lankford             4,875.00             1.9500

Lithotripters, Inc.           N/A (3)            6.0500

Mark McCaughan              2,500.00             1.0000

Alvie Carl McCully          2,500.00             1.0000

David Miles                 3,250.00             1.3000

Thomas Mobley                 937.58             0.4167

Bert Morrow                 4,500.00             1.8000

Dan Myers                     937.58             0.4167

Robert C. Newman            5,375.00             2.1500

Enrique Panlilio            2,500.00             1.0000

Greg Parr                   1,250.00             0.5000

Jack Paulk                  4,875.00             1.9500

Dennis Peters               2,500.00             1.0000

William Eugene Potts, Jr.   2,500.00             1.0000

Tony Rand                     937.58             0.4167

Edward Rietze                 937.58             0.4167

Raleigh Rollins             2,500.00             1.0000

Tom Sanders                 2,500.00             1.0000

W. Paul Sawyer              2,500.00             1.0000

Scott Sellinger             2,500.00             1.0000

Fouad Shami                 2,500.00             1.0000

John Sharpe                 4,875.00             1.9500

David Sneed                 4,125.00             1.6500

James C. Springer           2,500.00             1.0000

Thomas F. Stringer          2,500.00             1.0000

Harvey Taub                    N/A (4)           0.6500

Alan Terry                    937.58             0.4167

Derrick Thompson            2,500.00             1.0000

John W. Timmons             2,500.00             1.0000

Minoo Vaghaiwalla           3,250.00             1.3000

Dixon Walker                2,500.00             1.0000

John Wescot                 3,250.00             1.3000




<PAGE>


                                Cash            Percentage
General Partner         Contribution            Interest



Robert Youngman           $2,500.00              1.0000%

Thomas Zachos              2,500.00              1.0000

Nicholai Zelneranok        3,250.00              1.3000

         TOTAL          $245,187.58            100.0000

(1)      Fran Deture purchased his limited partnership  interest from the Estate
         of David Drylie and, therefore,  he made no capital contribution to the
         Partnership.

(2)      Dennis  Healey  received  his limited  partnership  interest  due to an
         assignment from the Estate of Byron H. McCormick and,  therefore,  made
         no capital contribution to the Partnership.

(3)  Lithotripters,  Inc. purchased its limited partnership interest pursuant to
     various assignments from existing Limited Partners and, therefore,  made no
     capital contribution to the Partnership as a result of its purchase of such
     interest.

(4)      Harvey  Taub  received  his  limited  partnership  interest  due  to an
         assignment from the Estate of Byron H. McCormick and,  therefore,  made
         no capital contribution to the Partnership.




<PAGE>



                               FOURTH AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                   INDIANA LITHOTRIPTERS LIMITED PARTNERSHIP I

                  THIS  AMENDMENT,  effective  as of the 30th day of  September,
1999,  is  entered  into by and  among  Lithotripters,  Inc.,  a North  Carolina
corporation and the General Partner of Indiana Lithotripters Limited Partnership
I, an Indiana limited partnership (the "Partnership"),  and the Limited Partners
of the Partnership.

                                R E C I T A L S:
                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred  to as  the  "Partners,"  are  parties  to  that  certain
Agreement of Limited Partnership of Indiana Lithotripters Limited Partnership I,
as amended (the "Agreement").

                  2. Effective as of September 30, 1999, the General Partner and
the  requisite  percentage of the Limited  Partners  consented in writing to the
following  amendments to the Agreement,  such amendments  intended to: (i) allow
the General  Partner the  authority to  periodically  offer and sell  additional
limited  partner  interests  (a  "Dilution  Offering")  to local  investors;(ii)
clarify and strengthen the  noncompetition  provisions of Articles 15.3 and 18.3
of the  Agreement;  (iii) add a new  provision  to the  Agreement to prevent the
disclosure  of  Confidential   Partnership   Information  that  might  harm  the
Partnership and its Partners;  and (iv) allow the General  Partner,  in its sole
discretion, to elect to assign to the Partnership its rights under Article 18 of
the Agreement to purchase the Partnership Interest of any deceased, insolvent or
competing Limited Partner:

                  NOW,  THEREFORE,  in accordance with Articles 28 and 29 of the
Partnership Agreement and pursuant to the written consent of the General Partner
and the requisite  percentage of the Limited Partners,  the parties hereto agree
as follows:

                           The  Agreement  is  hereby  amended  as set  forth in
                           Exhibits A, B and C attached hereto.

                            [Signature Page Follows]



                                                        -1-


<PAGE>




                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                           GENERAL PARTNER:

                           LITHOTRIPTERS, INC., a North Carolina corporation and
                              sole general partner of the Partnership

                               By:_________________________________________
                               Title:________________________________________



                                                 ALL THE LIMITED PARTNERS OF
                                                 THE PARTNERSHIP WHOSE NAMES
                                                 APPEARED ON SCHEDULE A-3

                                         By:/s/ Joseph Jenkins, M.D.
                                         ---------------------------
                                                     Joseph Jenkins, M.D.
                                                     Attorney-in-Fact*
- --------
     *Pursuant  to a Power of  Attorney  given by the  Limited  Partners  in the
Agreement.



                                                        -2-


<PAGE>



                                    EXHIBIT A

                           DILUTION OFFERING AMENDMENT

1.       Capitalized  terms used in this Exhibit and not otherwise defined shall
         have  the  same  meaning  as  provided  in  the  Agreement  of  Limited
         Partnership  (the  "Partnership  Agreement")  of Indiana  Lithotripters
         Limited Partnership I (the "Partnership").

2.       The purpose of this Exhibit is to set forth a proposed amendment to the
         Partnership Agreement that would give the General Partner the authority
         periodically  to offer and sell additional  limited  partner  interests
         ("Dilution  Offerings") to local investors who are not Limited Partners
         in the Partnership ("Qualified  Investors").  As required by Article 29
         of the  Partnership  Agreement,  to be effective this amendment must be
         approved  by the  Partners  representing  two-thirds  of the  aggregate
         interests in the Partnership.

3.   The purposes of a Dilution Offering are (i) to raise additional capital for
     any valid Partnership  purposes,  and (ii) to assure the highest quality of
     patient care by admitting  Qualified  Investors to the Partnership who will
     be dedicated and motivated as owners to follow the Partnership's  treatment
     protocol,  and comply  with its  quality  assurance  and  outcome  analysis
     programs.  Any additional  capital raised by the  Partnership in a Dilution
     Offering  can be used for any  legitimate  Partnership  purpose,  including
     upgrading   the   imaging   components   of   the   Partnership's   Siemens
     Lithostar(TM)extracorporeal  shockwave lithotripter and funding Partnership
     expenses as the General Partner deems appropriate.

4.       In the event the Dilution  Offering  Amendment  receives the  requisite
         approval  of the  Limited  Partners,  the  General  Partner  intends to
         conduct a Dilution  Offering  for the  purposes  of raising  additional
         capital  to  upgrade  the  imaging   components  of  the  Partnership's
         Lithostar(TM) and to fund other Partnership expenses deemed appropriate
         by the General Partner.

5.       Any sale of limited  partner  interests  to  Qualified  Investors  will
         result in the  proportionate  dilution  of the  Partnership  Percentage
         Interests of the existing Partners;  i.e., the interests of the General
         Partner  and the  Limited  Partners in  Partnership  allocations,  cash
         distributions  and voting rights will be  proportionately  reduced by a
         successful Dilution Offering.

6.       The  General  Partner has  determined  that the  purchase  price per 1%
         Partnership  Interest offered in the initial planned Dilution  Offering
         will be at its fair market value as determined by an independent  third
         party appraiser.  The price for Units sold in future Dilution Offerings
         also must be at a price no less than fair market value as determined by
         the General Partner.

7.       Upon  the  successful  sale  of  Partnership  Interests  in a  Dilution
         Offering,  the General Partner will prepare and attach a new Schedule A
         to the  Partnership  Agreement  to reflect (i) the  Partners'  adjusted
         Percentage Interests in the Partnership,  and (ii) the admission of the
         new Limited Partners to the Partnership.



                                                        -3-


<PAGE>



                                    EXHIBIT B

                          NONCOMPETITION PROVISION AND
                      CONFIDENTIALITY PROVISION AMENDMENTS

                  Capitalized  terms  used in  this  Exhibit  and not  otherwise
defined  shall have the same  meaning as  provided in the  Agreement  of Limited
Partnership  (the  "Partnership  Agreement")  of Indiana  Lithotripters  Limited
Partnership I (the "Partnership").

                       Noncompetition Provision Amendment

                  Article 15.3 of the Partnership Agreement is hereby amended by
deleting the current  provision in its entirety and by substituting the language
set forth below:

                           15.3 Outside  Activities.  The Limited Partners agree
         that  they  owe  fiduciary   duties  to  the  Partnership   and,  as  a
         consequence,  each Limited  Partner (that is not the General Partner or
         an  Affiliate of the General  Partner)  agrees that he or she shall not
         engage in "Outside  Activities" (as defined below) in the "Market Area"
         (as  defined  below)  while  he or  she  is a  Limited  Partner  in the
         Partnership.   The  phrase  "Outside   Activities"  means  directly  or
         indirectly owning, leasing or subleasing a lithotripter (or any similar
         equipment or competing devices used for treating renal or biliary stone
         disease) or any other therapeutic equipment acquired by the Partnership
         as permitted by Article 4. Prohibited  indirect ownership shall include
         the direct or indirect  ownership of any interest in a business venture
         (through stock ownership,  partnership interest ownership, ownership by
         or through a close family  member,  or as otherwise  determined in good
         faith by the General Partner) involving the ownership, purchase, lease,
         sublease,  promotion,  management  or operation of a  lithotripter  (or
         similar  equipment  or competing  devices  used for  treating  renal or
         biliary stone disease) or other competing  device or equipment,  unless
         the  General  Partner  determines  that such  activity  by the  Limited
         Partners is not detrimental to the best interests of the Partnership.

                           Upon  the   termination  or  transfer  of  a  Limited
         Partner's  interest  in the  Partnership  for any  reason,  including a
         transfer  pursuant to Article  18.3  hereof,  the  withdrawing  Limited
         Partner shall not, for a period of two (2) years  following the date of
         his or her withdrawal,  engage in any Outside Activities in any "Market
         Area" in which the  Partnership is  transacting  business or within the
         prior  twelve  months  has   transacted   business   (the   "Restricted
         Facilities").  For the purposes of this Article 15.3,  the term "Market
         Area"  shall  mean  (i)  the  area  within  a ten  mile  radius  of any
         Restricted  Facility,  but if such  area is  determined  by a court  of
         competent  jurisdiction  to be too  broad,  then it shall mean (ii) the
         area within a five mile radius of any Restricted Facility,  but if such
         area is determined by a court of competent jurisdiction



                                                        -4-


<PAGE>



         to be too broad  then it shall  mean  (iii) the area  within a two mile
         radius of any Restricted Facility.

                           In the event a Limited  Partner wishes and intends to
         engage in an Outside  Activity in a Market Area, he or she must provide
         written notice of such intent to the General  Partner prior to engaging
         in the Outside Activity. The written notice shall be deemed an election
         by the Limited Partner to withdraw from the Partnership (the "Notice of
         Withdrawal"), and shall give the General Partner the purchase rights as
         provided in Article 18.3 hereof.  After the Notice of  Withdrawal,  the
         former Limited Partner may engage in an Outside  Activity in the Market
         Area only  after  waiting  the  period of two years  specified  in this
         Article  15.3.  In the  event of  breach  of the  waiting  period,  the
         Partnership  shall be  entitled  to any  remedy at law or  equity  with
         respect to such breach,  including without  limitation an injunction or
         suit for damages.

                           If a Limited Partner during his or her  participation
         in the  Partnership  engages in an Outside  Activity  in a Market  Area
         without  first  notifying  the  General  Partner in  violation  of this
         Article  15.3,  the  Limited  Partner  shall be deemed to have  given a
         Notice of  Withdrawal  on the date the General  Partner  first  becomes
         aware of the Limited  Partner's  Outside  Activity in the Market  Area.
         Upon receiving a Limited  Partner's  Notice of Withdrawal or equivalent
         thereof, the General Partner may invoke the purchase rights provided in
         Article 18.3 and shall be entitled to any other remedy at law or equity
         including without limitation an injunction or suit for damages.

                  Article 18.3 of the Partnership Agreement is hereby amended by
deleting the current  provision in its entirety and by substituting the language
set forth below.

                           18.3 Breach of Article 15.3. In the event the General
         Partner  either  receives a Notice of Withdrawal as provided in Article
         15.3 or  receives  notice  of a breach  of  Article  15.3 by a  Limited
         Partner (the  "Defaulting  Limited  Partner"),  the General Partner may
         elect, in its sole  discretion,  to treat such event as a default under
         this  Agreement and enforce the provisions of this Article 18.3. If the
         General  Partner elects to enforce the provisions of this Article 18.3,
         the General  Partner  shall give written  notice of such  election (the
         "Notice of Default") to the Defaulting  Limited Partner within 180 days
         of the date the General Partner first received notice of the defaulting
         event.  Upon giving the Notice of Default,  the General  Partner  shall
         have the option to  purchase  at the  Closing  (as  defined  below) the
         Partnership   Interest  of  the  Defaulting   Limited   Partner  (which
         Defaulting  Limited  Partner  shall then become  obligated to sell such
         Partnership Interest) at the price determined in the manner provided in
         Article 18.5 of this Agreement and on the terms and conditions provided
         in Article 18.6 of this  Agreement.  The General  Partner  shall have a
         period of thirty (30) days  following the date of the Notice of Default
         (the "Option Period") within



                                                        -5-


<PAGE>



         which to notify in writing the Defaulting Limited Partner,  whether the
         General  Partner wishes to purchase all or a portion of the Partnership
         Interest of the Defaulting Limited Partner. If the General Partner does
         not elect to purchase the entire Partnership Interest of the Defaulting
         Limited  Partner  before the expiration of the Option Period and in the
         manner provided  herein,  the portion of the  Partnership  Interest not
         purchased shall be held by the Defaulting  Limited Partner  pursuant to
         the terms of this Agreement.

                       Confidentiality Provision Amendment

                  Article 15 of the  Partnership  Agreement is hereby amended by
adding a new Article 15.4 as set forth below:

                           15.4  Disclosure of  Confidential  Information.  Each
         Limited Partner  acknowledges and agrees that his or her  participation
         in the Partnership under this Agreement necessarily involves his or her
         understanding  of  and  access  to  certain  trade  secrets  and  other
         confidential information pertaining to the business of the Partnership.
         Accordingly,  each Limited  Partner (other than the General Partner and
         its Affiliates  that may also hold Limited  Partner  interests)  agrees
         that at all times during his or her participation in the Partnership as
         a Limited  Partner  and  thereafter,  he or she will not,  directly  or
         indirectly,  without the express written  authority of the Partnership,
         unless  required  by law or directed by a  applicable  legal  authority
         having  jurisdiction over the Limited Partner,  disclose or use for the
         benefit of any  person,  corporation  or other  entity  (other than the
         Partnership),   or  himself  or  herself,  (i)  any  trade,  technical,
         operational, management or other secrets, any patient or customer lists
         or  other  confidential  or  secret  data,  or any  other  proprietary,
         confidential  or  secret  information  of the  Partnership  or (ii) any
         confidential  information concerning any of the financial arrangements,
         financial positions, hospital or physician contracts, third party payor
         arrangements,   quality   assurance  and  outcome  analysis   programs,
         competitive   status,   customer   or   supplier   matters,    internal
         organizational matters,  technical abilities, or other business affairs
         of or relating to the Partnership. The Limited Partners (other than the
         General  Partner and its Affiliates  that may also hold Limited Partner
         interests)   acknowledge   that  all  of  the   foregoing   constitutes
         proprietary  information,  which  is  the  exclusive  property  of  the
         Partnership.  In the event of breach of this Article 15.4 as determined
         by the General Partner, the Partnership shall be entitled to any remedy
         at law or  equity  with  respect  to  such  breach,  including  without
         limitation, an injunction or suit for damages.



                                                        -6-


<PAGE>



                                    EXHIBIT C

                      PURCHASE OPTION ASSIGNMENT AMENDMENT
                       -----------------------------------


                  Capitalized  terms  used in  this  Exhibit  and not  otherwise
defined  shall have the same  meaning as  provided in the  Agreement  of Limited
Partnership  (the  "Partnership  Agreement")  of Indiana  Lithotripters  Limited
Partnership I (the "Partnership").

                      Purchase Option Assignment Amendment

                  Articles  18.1,  18.2 and 18.3 are hereby amended to allow the
General  Partner to either exercise its purchase option rights during the Option
Period,  as provided in such Articles,  or to assign such purchase option rights
in whole or in part to the Partnership. If the General Partner's purchase option
rights are assigned to the Partnership as provided herein, the Partnership shall
have the right to use  Partnership  revenues  or  borrowings  to  exercise  such
rights.  Further,  Articles 18.5 and 18.6 are also amended by  substituting  the
Partnership as a purchaser to the extent the General Partner elects to assign to
the  Partnership  its purchase option rights under Articles 18.1, 18.2 and 18.3.
If the Partnership acquires a Partnership Interest pursuant to the terms of this
Amendment, then the General Partner shall have the authority to amend Schedule A
to the  Partnership  Agreement to reflect the deletion of the interests  held by
the selling Limited Partners (or their  successors in interest),  and to reflect
the increased  Percentage Interests of the remaining Partners resulting from the
redemption.



                                                        -7-


<PAGE>



                               SIXTH AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
                 TEXAS LITHOTRIPSY LIMITED PARTNERSHIP III L.P.


                  THIS AMENDMENT, effective as of the 1st day of November, 1999,
is entered  into by and among  Pacific  Lithotripsy,  a North  Carolina  general
partnership and the General Partner of Texas Lithotripsy Limited Partnership III
L.P., a Texas limited partnership (the "Partnership"),  and the Limited Partners
of the Partnership.

                                R E C I T A L S:
                                 ---------------

     1. The General Partner and the Limited Partners,  hereinafter  collectively
referred to as the "Partners," are parties to that certain  Agreement of Limited
Partnership of Texas Lithotripsy  Limited  Partnership III L.P., as amended (the
"Agreement").

                  2. Effective as of November 1, 1999,  the General  Partner and
the  requisite  percentage of the Limited  Partners  consented in writing to the
following  amendment  to the  Agreement,  such  amendment  intended to allow the
General Partner the authority to periodically  offer and sell additional limited
partner interests (a "Dilution Offering ") to local investors.

                  NOW,   THEREFORE,   in  accordance  with  Article  29  of  the
Partnership Agreement and pursuant to the written consent of the General Partner
and the requisite  percentage of the Limited Partners,  the parties hereto agree
as follows:

                           The  Agreement  is  hereby  amended  as set  forth in
                           Exhibit A hereto.

                                             [Signature Page Follows]



                                                        -1-


<PAGE>




                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                                   GENERAL PARTNER:

                                  PACIFIC LITHOTRIPSY, a North Carolina general
                                     partnership

                         By:  Lithotripters, Inc., a North Carolina  corporation
                                and a general partner of the Partnership

                                   By:_________________________________________
                                Title:________________________________________


                         By: LithoWest, Inc., a California corporation and a
                               general partner of the Partnership

                                   By: _______________________________________
                                Title: _____________________________________


                                      ALL THE LIMITED PARTNERS OF
                                      THE PARTNERSHIP WHOSE NAMES
                                      APPEARED ON SCHEDULE A-5

                                         By:/s/ Joseph Jenkins, M.D.
                                         ---------------------------
                                       Joseph Jenkins, M.D.
                                       Attorney-in-Fact*
- --------
     *Pursuant  to a Power of  Attorney  given by the  Limited  Partners  in the
Agreement.



                                                        -2-


<PAGE>


                                    EXHIBIT A

                           DILUTION OFFERING AMENDMENT

1.       Capitalized  terms used in this Exhibit and not otherwise defined shall
         have the same meaning as provided in the Limited Partnership  Agreement
         (the "Partnership  Agreement") of Texas Lithotripsy Limited Partnership
         III L.P. (the "Partnership"), and any amendments thereto.

2.       The purpose of this Exhibit is to set forth a proposed amendment to the
         Partnership Agreement that would give the General Partner the authority
         periodically  to offer and sell additional  limited  partner  interests
         ("Dilution  Offering") to local urologists who are not investors in the
         Partnership ("Qualified  Investors").  As required by Article 29 of the
         Partnership Agreement,  to be effective this amendment must be approved
         by the Partners  representing  two-thirds of the aggregate interests in
         the Partnership.

3.       The purposes of a Dilution Offering are (i) to raise additional capital
         for any  valid  Partnership  purpose,  and (ii) to assure  the  highest
         quality  of  patient  care  by  admitting  Qualified  Investors  to the
         Partnership who will be dedicated and motivated as owners to follow the
         Partnership's treatment protocol, and comply with its quality assurance
         and outcome  analysis  programs.  Any additional  capital raised by the
         Partnership  in a  Dilution  Offering  can be used  for any  legitimate
         Partnership purpose including upgrading the Partnership's Lithostar(TM)
         Mobile System.

4.       Any sale of limited  partner  interests  to  Qualified  Investors  will
         result in the  proportionate  dilution  of the  Partnership  Percentage
         Interests of the existing Partners;  i.e., the interests of the General
         Partner  and the  Limited  Partners in  Partnership  allocations,  cash
         distributions  and voting rights will be  proportionately  reduced by a
         successful Dilution Offering.

5.       The  Percentage  Interests of the existing  Partners  cannot be diluted
         through  Dilution  Offerings by more than 20% in the aggregate  without
         the  prior  written  consent  of a  Majority  in  Interest  of all  the
         Partners.  Without  obtaining  this  additional  consent,  the existing
         Partners  cannot  be  diluted  to less  than  80% of  their  Percentage
         Interest ownership at the time of this Amendment.

6.       The  General  Partner has  determined  that the  purchase  price per 1%
         Partnership  Interest offered in the initial planned Dilution  Offering
         will be at its fair market value as determined by an independent  third
         party appraiser.  The price for Units sold in future dilution offerings
         also must be at a price no less than fair market value as determined by
         the General Partner.

7.       Upon  the  successful  sale  of  Partnership  Interests  in a  Dilution
         Offering,  the General Partner will prepare and attach a new Schedule A
         to the  Partnership  Agreement  to reflect (i) the  Partners'  adjusted
         Percentage Interests in the Partnership,  and (ii) the admission of the
         new Limited Partners to the Partnership.



                                                        -3-


<PAGE>



                        AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                           MOBILE KIDNEY STONE CENTERS
                             OF CALIFORNIA II, L.P.



<PAGE>



                                    AGREEMENT

                             OF LIMITED PARTNERSHIP

                                       OF

               MOBILE KIDNEY STONE CENTERS OF CALIFORNIA II, L.P.
               --------------------------------------------------


                                TABLE OF CONTENTS

                                                                    Page

         1.       FORMATION...........................................1
                  ---------

         2.       NAME................................................1
                  ----

         3.       OFFICES.............................................1
                  -------

         4.       PURPOSE.............................................2
                  -------

         5.       TERM................................................2
                  ----

         6.       CERTAIN DEFINED TERMS...............................2
                  ---------------------

         7.       CAPITAL CONTRIBUTIONS AND DILUTION OFFERINGS........6
                  --------------------------------------------

         8.       GUARANTIES..........................................7
                  ----------

         9.       CONDITIONS TO THE CAPITAL CONTRIBUTIONS OF CERTAIN LIMITED
                  ----------------------------------------------------------
                  PARTNERS.............................................7
                  --------

         10.      REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE GENERAL
                  --------------------------------------------------------
                  PARTNER..............................................7
                  -------

         11.      ADMISSION OF LIMITED PARTNERS........................8
                  -----------------------------

         12.      CAPITAL ACCOUNTS.....................................9
                  ----------------

         13.      ALLOCATIONS.........................................10
                  -----------

         14.      DISTRIBUTIONS.......................................11
                  -------------

         l5.      RIGHTS AND OBLIGATIONS OF LIMITED PARTNERS..........12
                  ------------------------------------------

         16.      LIMITED LIABILITY...................................14
                  -----------------

         17.      TRANSFER OF INTERESTS AND ADMISSION OF PARTNERS.....14
                  -----------------------------------------------


                                                         i


<PAGE>




         18.      OPTIONAL PURCHASE OF LIMITED PARTNERSHIP INTERESTS ON CERTAIN
                  -------------------------------------------------------------
                  EVENTS................................................18
                  ------

         19.      SALE, ASSIGNMENT OR OTHER TRANSFER OF THE GENERAL PARTNER'S
                  -----------------------------------------------------------
                  INTEREST..............................................24
                  --------

         20.      TERMINATION OF THE SERVICES OF THE GENERAL PARTNER....25
                  --------------------------------------------------

         21.      MANAGEMENT AND OPERATION OF BUSINESS..................25
                  ------------------------------------

         22.      RESERVES..............................................28
                  --------

         23.      INDEMNIFICATION AND EXCULPATION
                         OF THE GENERAL PARTNER.........................28


         24.      DISSOLUTION OF THE PARTNERSHIP........................29
                  ------------------------------

         25.      DISTRIBUTION UPON DISSOLUTION.........................30
                  -----------------------------

         26.      BOOKS OF ACCOUNT, RECORDS AND REPORTS.................31
                  -------------------------------------

         27.      NOTICES...............................................32
                  -------

         28.      AMENDMENTS............................................32
                  ----------

         29.      LIMITATIONS ON AMENDMENTS.............................32
                  -------------------------

         30.      MEETINGS, CONSENTS AND VOTING.........................33
                  -----------------------------

         31.      SUBMISSIONS TO THE LIMITED PARTNERS...................33
                  -----------------------------------

         32.      ADDITIONAL DOCUMENTS..................................33
                  --------------------

         33.      SURVIVAL OF RIGHTS....................................34
                  ------------------

         34.      INTERPRETATION AND GOVERNING LAW......................34
                  --------------------------------

         35.      SEVERABILITY..........................................34
                  ------------

         36.      AGREEMENT IN COUNTERPARTS.............................34
                  -------------------------

         37.      THIRD PARTIES.........................................34
                  -------------

         38.      POWER OF ATTORNEY.....................................34
                  -----------------



                                                        ii


<PAGE>



         39.      ARBITRATION...........................................35
                  -----------

         40.      CREDITORS.............................................35
                  ---------


                                    SCHEDULES

Schedule A  -  Schedule of Partnership Interests


                                       iii


<PAGE>



THE  LIMITED  PARTNERSHIP  INTERESTS  REPRESENTED  BY THIS  LIMITED  PARTNERSHIP
AGREEMENT HAVE NOT BEEN REGISTERED  WITH THE SECURITIES AND EXCHANGE  COMMISSION
UNDER THE  SECURITIES ACT OF 1933, AS AMENDED,  UNDER THE  CALIFORNIA  CORPORATE
SECURITIES LAW OF 1968, AS AMENDED,  OR REGISTERED UNDER SIMILAR LAWS OR ACTS OF
OTHER  STATES IN RELIANCE  UPON  EXEMPTIONS  UNDER SUCH LAWS.  IN  ADDITION,  NO
TRANSFERS OF LIMITED  PARTNERSHIP  INTERESTS MAY BE MADE WITHOUT COMPLIANCE WITH
THE RESTRICTIONS SET FORTH IN ARTICLE 17 BELOW.

                                    AGREEMENT

                             OF LIMITED PARTNERSHIP

                                       OF

                           MOBILE KIDNEY STONE CENTERS
                             OF CALIFORNIA II, L.P.

                  THIS AGREEMENT OF LIMITED  PARTNERSHIP  (the  "Agreement")  is
made  as of  April  1,  1999,  by and  among  MOBILE  KIDNEY  STONE  CENTERS  OF
CALIFORNIA,  LTD., a California limited partnership (the "General Partner"), and
persons listed on Schedule A attached hereto as the Limited Partners.

                  1.       FORMATION.
                           ---------

                  The  Partnership  was  formed  pursuant  to the  filing in the
Office of the Secretary of State of California on or about  December 11, 1998 of
a Certificate of Limited  Partnership  in accordance  with the provisions of the
Act.

                  2.       NAME.
                           ----

     2.1 The  name  of the  Partnership  is  "Mobile  Kidney  Stone  Centers  of
California II, L.P."

                  2.2 The  Partnership  business  shall be conducted  under such
names as the General  Partner may from time to time deem necessary or advisable,
provided that appropriate amendments to this Agreement and all necessary filings
under  applicable  assumed  or  fictitious  name  statutes  or the Act are first
obtained.

                  3.       OFFICES.
                           -------

                  3.1 The principal office of the Partnership  shall be at 15195
National Avenue, Suite 203, Los Gatos,  California 95032, or at such other place
as the  General  Partner  may be  required  to  maintain  within  the  State  of
California pursuant to the Act or may otherwise, from time to time, designate by
notice to the Limited Partners (the "Records Office").


                                       -1-


<PAGE>



                  3.2 The Partnership  may have such  additional  offices as the
General Partner may, from time to time, deem necessary or advisable.

                  4.       PURPOSE.
                           -------

                  The purpose and business of the  Partnership  shall be: (i) to
acquire and operate one or more transportable  lithotripters (or any other renal
stone treatment  equipment) for the treatment of renal stones primarily within a
150 mile radius of  Sacramento,  California or in such other  location(s) as the
General  Partner  may  determine,  in its  sole  discretion,  to be in the  best
interests  of the  Partnership;  (ii) to acquire  and  operate in the future any
other urological  device or equipment;  provided,  that such equipment as of the
date of  acquisition  by the  Partnership  has received FDA premarket  approval;
(iii)  to  acquire  an  interest  in any  business  entity,  including,  without
limitation,  a limited  partnership,  limited  liability company or corporation,
that engages in any business  activity  described in this Article 4; and (iv) to
engage in any and all activities  incidental or related to the  foregoing,  upon
and subject to the terms and conditions of this Agreement.

                  5.       TERM.
                           ----

                  The Partnership  shall terminate on December 31, 2049,  unless
sooner terminated as herein provided.

                  6.       CERTAIN DEFINED TERMS.
                           ---------------------

                  Certain terms used in this Agreement  shall have the following
meanings:

     Act. The Act means the California Revised Limited  Partnership Act, as then
in effect.

                  Affiliate.  An  Affiliate  is  (i)  any  person,  partnership,
corporation, association or other legal entity ("person") directly or indirectly
controlling, controlled by or under common control with another person; (ii) any
person owning or controlling 10% or more of the  outstanding  voting interest of
such other person;  (iii) any officer,  director or partner of such person;  and
(iv) if such other  person is an officer,  director  or partner,  any entity for
which such person acts in such capacity.

     Agreement.  This  Agreement  of  Limited  Partnership,  as the  same may be
amended from time to time.

     Bank. First-Citizens Bank & Trust Company, its successors and assigns.

     Capital Account.  The Partnership  capital account of a Partner as computed
pursuant to Article 12 of this Agreement.



                                                        -2-


<PAGE>



                  Capital  Contributions.  All capital  contributions  made by a
Partner or his or her  predecessor  in  interest  which shall  include,  without
limitation, contributions made pursuant to Article 7 of this Agreement.

     Capital  Transaction.  Any transaction which, were it to generate proceeds,
would produce Partnership Sales Proceeds or Partnership Refinancing Proceeds.

     Code.  The Internal  Revenue  Code of 1986,  as amended,  or  corresponding
provisions of subsequent, superseding revenue laws.

                  Dilution  Offering.   As  provided  in  Article  7.4  of  this
Agreement,  the future offering of additional limited  partnership  interests in
the  Partnership  as  determined  by the General  Partner.  Except as  otherwise
provided in Article 7.4, any successful  Dilution Offering will  proportionately
reduce the Percentage Interests of the then current Partners in the Partnership.

     Domestic Proceeding. Any divorce, annulment, separation or similar domestic
proceeding between a married couple.

                  Equipment.   The  equipment  used  in  the  operation  of  the
Lithotripter  System,  including the mobile transport vehicle, the transportable
lithotripter and miscellaneous  medical equipment and supplies,  and any similar
additional equipment acquired by the Partnership in the future.

                  FDA.  The United States Food and Drug Administration.


     General  Partner.  The general  partner of the  Partnership,  Mobile Kidney
Stone Centers of California, Ltd., a California limited partnership.

                  Guaranty.  The  Guaranty  Agreement  pursuant  to  which  each
Limited Partner will guarantee a portion of the Partnership's obligations to the
Bank under the Loan.  The form of the  Guaranty  Agreement  is  included  in the
Subscription Packet accompanying the Memorandum.

                  Initial Limited Partner.  Stan Johnson,  a resident of Arizona
and an  Affiliate  of the general  partner of the General  Partner.  The Initial
Limited Partner is to be the only limited partner of the Partnership  until such
time as the new Limited Partners are admitted to the Partnership,  at which time
the Initial Limited Partner shall withdraw from the Partnership.

                  Limited Partners.  The Limited Partners are those investors in
the Units  admitted  to the  Partnership  and any person  admitted  as a Limited
Partner in accordance with the provisions of this Agreement.

     Lithotripter.  The extracorporeal shock-wave lithotripter to be acquired by
the Partnership and any replacements therefor or additional  lithotripters to be
purchased by the Partnership.


                                                        -3-


<PAGE>



     Lithotripter   System.   The  mobile  transport   vehicle  and  operational
Lithotripter.

                  Loan.  The  loan  of up to  $487,125  from  the  Bank  to  the
Partnership.  Loan  proceeds will be used by the  Partnership  to (i) acquire an
extracorporeal shockwave lithotripter with options (estimated at $400,000), (ii)
acquire  and upfit a mobile van to  transport  the  lithotripter  (estimated  at
$50,000)  and (iii) pay sales taxes on the purchase of the  Lithotripter  System
(estimated at $37,125).

     Losses.  The net loss (including Net Losses from Capital  Transactions)  of
the  Partnership  for each Year of the  Partnership  as  determined  for federal
income tax purposes.

                  Majority  in Interest  of the  Limited  Partners.  The Limited
Partners who hold more than 50% of the Percentage  Interests in the  Partnership
held by the Limited Partners.

     Memorandum.   The  Confidential   Private   Placement   Memorandum  of  the
Partnership dated January 13, 1999, as amended or as supplemented.

                  Net Gains from Capital Transactions. The gains realized by the
Partnership  as a result of or upon any sale,  exchange,  condemnation  or other
disposition of the capital assets of the Partnership (which assets shall include
Code Section 1231 assets) or as a result of or upon the damage or destruction of
such capital assets.

                  Net Losses from Capital  Transactions.  The losses realized by
the Partnership as a result of or upon any sale, exchange, condemnation or other
disposition of the capital assets of the  Partnership  (which shall include Code
Section 1231 assets) or as a result of or upon the damage or destruction of such
capital assets.

     Offering.  The offer to  potential  investors  of 60 Units  pursuant to the
Memorandum.

     Partners. The General Partner and the Limited Partners, collectively, where
no distinction is required by the context in which the term is used herein.

     Partnership.  Mobile  Kidney  Stone  Centers  of  California  II,  L.P.,  a
California limited partnership.

                  Partnership Cash Flow. For the applicable  period, the excess,
if any,  of (A) the sum of (i) all  gross  receipts  from  any  source  for such
period,  other than from  Partnership  loans,  Capital  Transactions and Capital
Contributions,  and (ii) any funds released by the  Partnership  from previously
established  reserves,  over  (B) the sum of (i) all cash  expenses  paid by the
Partnership  for such  period;  (ii) the amount of all  payments of principal on
loans to the Partnership;  (iii) capital  expenditures of the  Partnership;  and
(iv) such  reasonable  reserves as the General  Partner shall deem  necessary or
prudent to set aside for future repairs,  improvements or equipment  replacement
or additions,  or to meet working capital requirements or foreseen or unforeseen
future liabilities and contingencies of the Partnership; provided, however, that
the amounts referred to in (B)(i), (ii) and (iii) above shall


                                                        -4-


<PAGE>



be taken into  account  only to the extent not funded by Capital  Contributions,
loans or paid out of  previously  established  reserves.  Such term  shall  also
include all other funds deemed  available  for  distribution  and  designated as
"Partnership Cash Flow" by the General Partner.

     Partnership  Interest.  The  interest  of a Partner in the  Partnership  as
defined by the Act and this Agreement.

                  Partnership  Refinancing Proceeds.  The cash realized from the
refinancing of Partnership assets after retirement of any secured loans and less
(i) payment of all expenses  relating to the transaction and (ii)  establishment
of such  reasonable  reserves as the General  Partner  shall deem  necessary  or
prudent to set aside for future repairs,  improvements, or equipment replacement
or additions,  or to meet working capital requirements or foreseen or unforeseen
future liabilities or contingencies of the Partnership.

                  Partnership  Sales Proceeds.  The cash realized from the sale,
exchange,  casualty  or other  disposition  of all or a portion  of  Partnership
assets after the retirement of all secured loans and less (i) the payment of all
expenses  related to the transaction and (ii)  establishment  of such reasonable
reserves as the General Partner shall deem necessary or prudent to set aside for
future repairs,  improvements, or equipment replacement or additions, or to meet
working  capital  requirements or foreseen or unforeseen  future  liabilities or
contingencies of the Partnership.

                  Percentage  Interest.  The  interest  of each  Partner  in the
Partnership,  to be  determined  initially  in the case of a Limited  Partner by
reference to his or her Unit ownership based upon the Limited  Partners  holding
an aggregate 60% Percentage Interest in the Partnership,  with each initial Unit
sold representing an initial 1% interest. The General Partner will initially own
a 40% Percentage  Interest in the Partnership.  A Partner's  Percentage Interest
may be reduced by a future Dilution Offering. The Partners' Percentage Interests
in the Partnership as of the date hereof are as set forth in Schedule A attached
hereto. Any future  adjustments in the Partners'  Percentage  Interests,  due to
future Dilution Offerings or otherwise,  will also be reflected by amendments to
Schedule A.

     Profit. The net income of the Partnership (including Net Gains from Capital
Transactions)  for each Year of the Partnership as determined for federal income
tax purposes.

                  Pro  Rata  Basis.   In   connection   with  an  allocation  or
distribution,  an allocation  or  distribution  in proportion to the  respective
Percentage Interests of the class of Partners to which reference is made.

     Sales Agency  Agreement.  The sales agency agreement  through which MedTech
Investments,  Inc.,  an  Affiliate  of the General  Partner and a  broker-dealer
company  registered with the Securities and Exchange  commission and a member of
the National  Association of Securities  Dealers,  Inc. shall offer and sell the
limited partnership interest of the Partnership pursuant to the Memorandum.



                                                        -5-


<PAGE>



     Sales  Commission.  The $250 sales commission paid to MedTech  Investments,
Inc. for each Unit sold.

                  Service.  The Internal Revenue Service.


                  Units.   The  60  equal  limited  partner   interests  in  the
Partnership offered pursuant to the Memorandum for a price per Unit of $2,500 in
cash, plus a personal guaranty of 1% of the Partnership's  obligations under the
Loan (up to $4,871.25 principal guaranty obligation).

     Year. An annual accounting period ending on December 31 of each year during
the term of the Partnership.

                  7.       CAPITAL CONTRIBUTIONS AND DILUTION OFFERINGS.

                  7.1  General  Partner  Contribution.  On or before the date of
this  Agreement,  the  General  Partner  will  contribute  to the capital of the
Partnership  cash in the amount  equal to 40% (up to $100,000) of the total cash
contributed to the  Partnership by the Partners in the Offering made pursuant to
the Memorandum.

                  7.2 Limited Partner Contribution.  Each Limited Partner hereby
agrees to contribute and shall  contribute to the capital of the  Partnership on
the date of his or her  admission to the  Partnership  the cash amount set forth
opposite his or her name on Schedule A attached hereto.

     7.3 No Interest.  Except as otherwise provided herein, no interest shall be
paid on any contribution to the capital of the Partnership.

                  7.4 Dilution  Offerings.  If the General Partner,  in its sole
discretion,  determines that it is in the best interest of the Partnership,  the
General Partner may, from time to time, offer, sell and issue, for and on behalf
of the Partnership,  additional limited partnership interests in the Partnership
(a  "Dilution  Offering")  to  investors  who are not already  Limited  Partners
("Qualified  Investors").  The primary purpose of any Dilution Offering would be
to raise additional capital for any legitimate  Partnership purpose as set forth
in Article 4. Any limited partnership  interests offered by the Partnership in a
Dilution  Offering  shall  be sold in the  manner  and  according  to the  terms
prescribed in the sole  discretion of the General  Partner;  provided,  however,
that any additional limited partnership interests offered in a Dilution Offering
will be sold for a price no lower than the highest price for which proportionate
limited  partnership  interests in the Partnership  have been previously sold by
the Partnership unless otherwise determined by a vote of the General Partner and
a Majority in Interest of the Limited Partners.  Any sale of additional  limited
partnership  interests  will  result  in  the  proportionate   dilution  of  the
Percentage Interests of the existing Partners. Notwithstanding the above, in the
event of a  Dilution  Offering,  the  General  Partner  may  elect,  in its sole
discretion,   to  prevent   dilution  of  its  Percentage   Interest  by  either
contributing  additional  capital to the  Partnership  or purchasing  additional
limited partnership  interests in any Dilution Offering.  Limited Partners shall
have no right to purchase  additional  limited partner interests in any Dilution
Offering or to make


                                                        -6-


<PAGE>



additional capital contributions or take any other action to prevent dilution of
their Percentage Interest. Any investor acquiring a limited partnership interest
in a Dilution  Offering shall agree to be bound by the terms of this  Agreement,
and shall be automatically admitted as a Limited Partner of the Partnership. Any
adjustment  in the  Partners'  Percentage  Interests  resulting  from a Dilution
Offering shall be set forth on an amended Schedule A to be attached hereto.

                  8.       GUARANTIES.
                           ----------

                  Each Partner agrees to execute and deliver to the  Partnership
on the date of his or her admission to the  Partnership a Guaranty in the amount
set forth opposite his or her name on Schedule A attached hereto.

                  9.       CONDITIONS TO THE CAPITAL CONTRIBUTIONS OF CERTAIN
                           --------------------------------------------------
                           LIMITED PARTNERS.
                           ----------------

                  The  obligations  of  any  Limited  Partners  acquiring  their
Partnership  Interests  in the  Offering  or a  Dilution  Offering  to make cash
Capital   Contributions   hereunder  are  subject  to  the  condition  that  the
representations, warranties, agreements and covenants of the General Partner set
forth in Article 10 of this  Agreement are and shall be true and correct or have
been and will have been complied with in all material  respects on the date such
Capital  Contributions  are  required to be made,  except to the extent that any
such representation or warranty expressly pertains to an earlier date.

                  10.      REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE
                           ------------------------------------------------
                           GENERAL PARTNER.
                           ---------------

          10.1 The General Partner hereby represents and warrants to the Limited
     Partners  that:  (a) The  Partnership  is a limited  partnership  formed in
     accordance with and validly existing under the Act and the other applicable
     laws of the State of California;

                  (b) The interests in the  Partnership of the Limited  Partners
         will have been duly  authorized  or created and validly  issued and the
         Limited  Partners shall have no personal  liability to contribute money
         to the  Partnership  other than the amounts agreed to be contributed by
         them in the  manner  and on the  terms  set  forth  in this  Agreement,
         subject, however, to such limitations as may be imposed under the Act;

                  (c) Except as disclosed  in the  Memorandum  or  documentation
         prepared in connection with a Dilution Offering,  no material breach or
         default adverse to the Partnership  exists under the terms of any other
         material agreement affecting the Partnership; and

               (d) The  General  Partner  is a  California  limited  partnership
          formed and existing under the laws of the State of California.

          10.2 The General  Partner  hereby  covenants  to the Limited  Partners
     that:

                                                        -7-


<PAGE>



               (a) It will at all times act in a fiduciary  manner with  respect
          to the Partnership and the Limited Partners;

               (b)  Except as  provided  in  Article  19,  it will  serve as the
          General Partner of the Partnership until the Partnership is terminated
          without reconstitution; and

                  (c) It will cause the  Partnership  to carry  adequate  public
         liability,  property  damage and other insurance as is customary in the
         business to be engaged in by the Partnership.

                  11.      ADMISSION OF LIMITED PARTNERS.
                           -----------------------------

                  The  General  Partner may permit the offer and sale of limited
partnership  interests on the terms and conditions provided in the Memorandum or
future  Dilution  Offerings and may admit persons  subscribing  for interests as
Limited  Partners in the  Partnership  on the terms and  conditions set forth in
this Article 11.

                  (a) The General  Partner  shall have approved of the admission
         of said person in writing on such terms and  conditions  as the General
         Partner shall determine;

                  (b)  Said  person  shall  have  executed  such   documents  or
         instruments  as the General  Partner may deem necessary or desirable to
         effect his or her admission as a Limited Partner;

               (c) Said person shall have  accepted and adopted all of the terms
          and provisions of this Agreement, as then amended;

                  (d)  Said  person  (if a  corporation)  shall  deliver  to the
         General  Partner  a  certified  copy of a  resolution  of its  Board of
         Directors  authorizing  it to become a Limited  Partner under the terms
         and conditions of this Agreement; and

                  (e) Said person,  upon request by the General  Partner,  shall
         pay such reasonable  expenses as may be incurred in connection with its
         admission as a Limited Partner.

                  12.      CAPITAL ACCOUNTS.
                           ----------------

                  A Capital  Account shall be  established  for each Partner and
shall at all times be determined  and  maintained  in accordance  with the Final
Treasury  Regulations  under  Section  704(b)  of the  Code,  as the same may be
amended.  A Partner  shall not be entitled  to  withdraw  any part of his or her
Capital Account or to receive any distribution  from the Partnership,  except as
provided in Articles 14 and 25.

                  (a)      Each Partners' Capital Account shall be increased by:



                                                        -8-


<PAGE>



                         (i)  The  amount  of his or  her  Capital  Contribution
                    pursuant to Article 7; and

                         (ii) The  amount  of  Profits  allocated  to him or her
                    pursuant to Article 13; and

                           (iii) The Partner's pro rata share (determined in the
                  same  manner as such  Partner's  share of  Profits  and Losses
                  allocated pursuant to Article 13 hereof) of any income or gain
                  exempt from tax.

                  (b)      Each Partner's Capital Account shall be decreased by:

                         (i)  The  amount  of  Losses  allocated  to  him or her
                    pursuant to Article 13; and

                         (ii) The amount of Partnership  Cash Flow,  Partnership
                    Sales   Proceeds  and   Partnership   Refinancing   Proceeds
                    distributed to him or her pursuant to Article 14; and

                           (iii)  The  Partner's  pro rata  share  of any  other
                  expenditures  of the  Partnership  which are not deductible in
                  computing  Partnership  Profits  or  Losses  and which are not
                  added to the tax basis of any Partnership property, including,
                  without   limitation,   expenditures   described   in  Section
                  705(a)(2)(B) of the Code. The Partner's pro rata share of such
                  expenditures  shall be  determined  in the same manner as such
                  Partner's  share of Profits and Losses  allocated  pursuant to
                  Article 13.


                                                        -9-


<PAGE>



                  13.      ALLOCATIONS

                  (a)  Profits  and  Losses.  The  Profits  and  Losses  of  the
         Partnership  shall be allocated  among the Partners in accordance  with
         their  respective  Percentage  Interests.  In  allocating  Profits  and
         Losses,  Net Gains and  Losses  from  Capital  Transactions  (a part of
         Profits and Losses), if any, shall be allocated first.

                  (b)  Partnership  Minimum Gain  Chargeback.  If there is a net
         decrease in  Partnership  Minimum  Gain during any Year,  each  Partner
         shall be specially  allocated items of Partnership  income and gain for
         such Year (and, if necessary,  subsequent  Years) in an amount equal to
         such Partner's  share of the net decrease in Partnership  Minimum Gain,
         determined   in   accordance   with   Treasury    Regulations   Section
         1.704-2(g)(2).  Allocations made pursuant to the previous sentence will
         be  made  in  proportion  to  the  respective  amounts  required  to be
         allocated to each Partner  pursuant to that section of the Regulations.
         This  provision  relating to  Partnership  Minimum Gain  Chargebacks is
         intended to comply with Treasury  Regulations  Section  1.704-2(f)  and
         will be  interpreted  and  applied  in a manner  consistent  with  that
         Regulation.

                  (c)  Partner  Minimum  Gain  Chargeback.  If  there  is a  net
         decrease in Partner Minimum Gain attributable to a Partner  Nonrecourse
         Debt  during  any Year,  each  Partner  who has a share of the  Partner
         Minimum Gain  attributable  to such Partner  Nonrecourse  Debt shall be
         specially  allocated items of Partnership income and gain for such Year
         (and,  if  necessary,  subsequent  Years)  in an  amount  equal to such
         Partner's   share  of  the  net   decrease  in  Partner   Minimum  Gain
         attributable to such Partner  Nonrecourse  Debt, to the extent required
         and  determined  in  accordance  with  Treasury   Regulations   Section
         1.704-2(i)(4).  Allocations  pursuant to the previous  sentence will be
         made in proportion to the respective  amounts  required to be allocated
         to each  Partner  pursuant  to that  section of the  Regulations.  This
         provision  relating to Partner Minimum Gain  Chargebacks is intended to
         comply with Regulation  Section  1.704-2(i)(4)  and will be interpreted
         and applied in a manner consistent with that Regulation.

                  (d)  Qualified  Income  Offset.  If any  Partner  unexpectedly
         receives  any  adjustment,  allocation  or  distribution  described  in
         Treasury Regulations Section 1.704- 1(b)(2)(ii)(d)(4) through (6) which
         causes or increases a deficit balance in such Partner's Capital Account
         (adjusted  for  this  purpose  in  the  manner   provided  in  Treasury
         Regulations Section 1.704-1(b)(2)(ii)(d)),  items of Partnership income
         and gain shall be specially allocated to each such Partner in an amount
         and manner  sufficient  to  eliminate,  to the extent  required  by the
         Regulations,  the deficit Capital Account of such Partner as quickly as
         possible,  provided that an  allocation  pursuant to this Article 13(d)
         shall be made if and only to the extent that such Partner  would have a
         deficit  Capital  Account after all other  allocations  provided for in
         this Article 13 have been  tentatively  made as if this  Article  13(d)
         were  not  in  the  Agreement.  This  provision  is  intended  to  be a
         "qualified income offset," as defined in Treasury  Regulations  Section
         1.704-1(b)(2)(ii)(d),  such Regulation being specifically  incorporated
         herein by reference.


                                                       -10-


<PAGE>





                  (e) Sales Commission.  The Sales Commission shall be allocated
         to the  Units  which  are  not  held  by the  General  Partner  and its
         Affiliates  and are  acquired  in the  Offering  in  proportion  to the
         respective capital contributions  represented by such Units (i.e., $250
         in Sales  Commissions per each such Unit).  The purpose of this Article
         13(e)  is to  allocate  the  Sales  Commission  to those  Partners  who
         actually bore the burden of paying the Sales Commission.

                  (f)  Allocations  Between  Transferor and  Transferee.  In the
         event of the transfer (other than the pledges of the General  Partner's
         interest  permitted  by Article 19 or  Permitted  Pledges  described in
         Article  17.2(b))  of all or  any  part  of a  Partner's  interest  (in
         accordance with the provisions of this Agreement) in the Partnership at
         any time other  than at the end of a Year,  or the  admission  of a new
         Partner  (in  accordance  with  the  terms  of  this  Agreement),   the
         transferring  Partner  or new  Partner's  share  of  the  Partnership's
         income,  gain,  loss,  deductions  and  credits,  as computed  both for
         accounting  purposes  and for  federal  income tax  purposes,  shall be
         allocated between the transferor Partner and the transferee Partner (or
         Partners),  or the new Partner and the other Partners,  as the case may
         be, in the same  ratio as the  number of days in such Year  before  and
         after the date of the transfer or admission; provided, however, that if
         there  has  been a sale  or  other  disposition  of the  assets  of the
         Partnership  (or any part thereof)  during such Year,  then the General
         Partner may elect, in its sole discretion,  to treat the periods before
         and after the date of the transfer or  admission as separate  Years and
         allocate the Partnership's net income,  gain, net loss,  deductions and
         credits for each of such deemed  separate  Years.  Notwithstanding  the
         foregoing, the Partnership's "allocable cash basis items," as that term
         is used in Section  706(d)(2)(B)  of the Code,  shall be  allocated  as
         required  by  Section   706(d)(2)  of  the  Code  and  the  regulations
         thereunder.

                  (g) Tax  Withholding.  The Partnership  shall be authorized to
         pay, on behalf of any  Partner,  any amounts to any  federal,  state or
         local taxing  authority,  as may be necessary  for the  Partnership  to
         comply with tax withholding  provisions of the Code or the other income
         tax or  revenue  laws  of any  taxing  authority.  To  the  extent  the
         Partnership  pays any such  amounts  that it may be  required to pay on
         behalf  of  a  Partner,  such  amounts  shall  be  treated  as  a  cash
         distribution  to such  Partner  and shall  reduce the amount  otherwise
         distributable to such Partner.

                  14.      DISTRIBUTIONS.
                           -------------

                  (a)  Distribution of Partnership  Cash Flow.  Partnership Cash
         Flow shall be distributed to the Partners  within 60 days after the end
         of each Year, or earlier in the discretion of the General  Partner,  in
         proportion  to their  respective  Percentage  Interests  at the time of
         distribution.

               (b)   Distribution  of  Partnership   Refinancing   Proceeds  and
          Partnership  Sales  Proceeds.  Partnership  Refinancing  Proceeds  and
          Partnership Sales Proceeds shall be



                                                       -11-


<PAGE>



         distributed to the Partners  within 60 days of the Capital  Transaction
         giving  rise to such  proceeds,  or  earlier in the  discretion  of the
         General Partner, in proportion to their respective Percentage Interests
         at the time of distribution.

                  (c)  Distribution  in  Liquidation.  Upon  liquidation  of the
         Partnership,  all of the  Partnership's  property  shall  be  sold  and
         Profits and Losses allocated accordingly. Proceeds from the liquidation
         of the Partnership shall be distributed in accordance with Article 25.

                  l5.      RIGHTS AND OBLIGATIONS OF LIMITED PARTNERS.
                           ------------------------------------------

                  15.1  Management.  The Limited Partners shall not take part in
the management of the business,  nor transact any business for the  Partnership,
nor  shall  they  have  power  to  sign  for or to  bind  the  Partnership.  The
Partnership may,  however,  contract with one or more Limited Partners to act as
the local medical director(s) of the Lithotripter System. No Limited Partner may
withdraw from the Partnership except as expressly permitted herein.

                  15.2 Operation of Lithotripter  System.  The Limited  Partners
shall not  operate  or  utilize  the  Partnership  Lithotripter  System or other
Partnership  equipment except pursuant to (i) an agreement with the Partnership;
or (ii) any other arrangement specifically approved by the General Partner.

                  15.3 Outside Activities.  The Limited Partners agree that they
owe fiduciary  duties to the  Partnership  and, as a  consequence,  each Limited
Partner (that is not the General Partner or an Affiliate of the General Partner)
agrees that (s)he shall not engage in "Outside Activities" (as defined below) in
the "Market  Area" (as defined  below)  while(s)he  is a Limited  Partner in the
Partnership  and shall  otherwise be subject to the  provisions  of this Article
15.3.  The phrase  "Outside  Activities"  means  directly or indirectly  owning,
leasing or  subleasing  a  lithotripter  (or any similar  equipment or competing
devices  used  for  treating  renal  or  biliary  stone  disease)  or any  other
therapeutic  equipment  acquired by the Partnership;  provided that an ownership
interest in the General Partner or an Affiliate of the General Partner shall not
constitute an Outside  Activity.  Prohibited  indirect  ownership  shall include
without  limitation  the  direct or  indirect  ownership  of any  interest  in a
business  venture  (through stock  ownership,  partnership  interest  ownership,
ownership by or through a close family  member,  or as otherwise  determined  in
good faith by the General  Partner)  involving the ownership,  purchase,  lease,
sublease,  promotion,  management  or  operation of a  lithotripter  (or similar
equipment or competing devices used for treating renal or biliary stone disease)
or other competing  device or equipment,  unless the General Partner  determines
that such  activity  by the  Limited  Partners  is not  detrimental  to the best
interests of the Partnership;  provided,  however, that the General Partner may,
in its sole  discretion,  waive the provisions of this Section 15.3 with respect
to any ownership  interest of a Limited Partner in an Outside Activity  acquired
before the date hereof.  Notwithstanding  the above, a Limited Partner shall not
be  prohibited  from owning less than 1% of the capital stock  (calculated  on a
fully diluted basis) of a corporation whose stock is publicly owned or regularly
traded on any public exchange.

                  Upon  the  termination  or  transfer  of a  Limited  Partner's
interest in the  Partnership  for any reason,  including a transfer  pursuant to
Article 18.3 hereof, the withdrawing  Limited Partner shall not, for a period of
two (2) years following the date of withdrawal, engage in any Outside Activities


                                                       -12-


<PAGE>



in any "Market Area" in which the Partnership is transacting  business or within
the prior twelve months has transacted  business (the "Restricted  Facilities").
For the purposes of this Article 15.3, the term "Market Area" shall mean (i) the
area within a fifty (50) mile  radius of any  Restricted  Facility,  but if such
area is determined by a court of competent jurisdiction to be too broad, then it
shall  mean (ii) the area  within a thirty  (30) mile  radius of any  Restricted
Facility, but if such area is determined by a court of competent jurisdiction to
be too broad then it shall mean (iii) the area within a fifteen (15) mile radius
of any Restricted Facility.

                  In the event a Limited Partner wishes and intends to engage in
an Outside  Activity in a Market Area, he or she must provide  written notice of
such intent to the General  Partner  prior to engaging in the Outside  Activity.
The  written  notice  shall be deemed an  election  by the  Limited  Partner  to
withdraw from the Partnership (the "Notice of  Withdrawal"),  and shall give the
General  Partner the purchase  rights as provided in Article 18.3 hereof.  After
the Notice of Withdrawal,  the former  Limited  Partner may engage in an Outside
Activity in the Market Area only after waiting the period of two years specified
in this  Article  15.3.  In the  event of  breach  of the  waiting  period,  the
Partnership  shall be entitled  to any remedy at law or equity  with  respect to
such breach, including without limitation an injunction or suit for damages.

                  If a Limited  Partner during his or her  participation  in the
Partnership  engages in an  Outside  Activity  in a Market  Area  without  first
notifying  the General  Partner in violation of this Article  15.3,  the Limited
Partner  shall be deemed to have  given a Notice of  Withdrawal  on the date the
General Partner first becomes aware of the Limited Partner's Outside Activity in
the Market Area.  Upon  receiving a Limited  Partner's  Notice of  Withdrawal or
equivalent  thereof,  the Partnership may invoke the purchase rights provided in
Article  18.3  and  shall be  entitled  to any  other  remedy  at law or  equity
including without limitation an injunction or suit for damages.

                  15.4  Disclosure  of  Confidential  Information.  Each Limited
Partner acknowledges and agrees that his or her participation in the Partnership
under this Agreement necessarily involves his or her understanding of and access
to certain trade secrets and other  confidential  information  pertaining to the
business of the Partnership.  Accordingly,  each Limited Partner (other than the
General   Partner  and  its  Affiliates  that  may  also  hold  Limited  Partner
Partnership  Interests) agrees that at all times during his or her participation
in the Partnership as a Limited Partner and thereafter, (s)he will not, directly
or indirectly, without the express written authority of the Partnership,  unless
required by law or directed by a applicable legal authority having  jurisdiction
over  the  Limited  Partner,  disclose  or use for the  benefit  of any  person,
corporation  or other  entity  (other  than  the  Partnership),  or the  Limited
Partner, (i) any trade, technical, operational, management or other secrets, any
patient or customer  lists or other  confidential  or secret data,  or any other
proprietary,  confidential or secret  information of the Partnership or (ii) any
confidential information concerning any of the financial arrangements, financial
condition,  hospital or  physician  contracts,  third party payor  arrangements,
quality assurance and outcome analysis programs, competitive status, customer or
supplier matters, internal organizational matters, technical abilities, or other
business affairs of or relating to the Partnership.  The Limited Partners (other
than the General  Partner and its Affiliates  that may also hold Limited Partner
Partnership Interests) acknowledge that all of the foregoing


                                                       -13-


<PAGE>



constitutes  proprietary  information,  which is the  exclusive  property of the
Partnership.  In the event of breach of this Article 15.4 as  determined  by the
General  Partner,  the  Partnership  shall be  entitled  to any remedy at law or
equity with respect to such breach, including without limitation,  an injunction
or suit for damages.

                  16.      LIMITED LIABILITY.
                           -----------------

                  No Limited Partner shall be required to make any  contribution
to the  capital of the  Partnership  except as set forth in Article 7, nor shall
any Limited  Partner in his or her capacity as such,  be bound by, or personally
liable for, any expense,  liability or obligation of the  Partnership  except to
the extent of his or her (i) interest in the  Partnership;  (ii)  Guaranties  of
Partnership  obligations;  and (iii) obligation to return  distributions made to
him or her under certain circumstances as required by the Act.

                  17.      TRANSFER OF INTERESTS AND ADMISSION OF PARTNERS.
                           -----------------------------------------------

                  17.1     Transferability.
                           ---------------

                  (a) The  term  "transfer"  when  used in this  Agreement  with
         respect to a Partnership  Interest includes a sale,  assignment,  gift,
         pledge,  exchange  or any other  disposition  (but does not include the
         issuance of new Partnership Interests pursuant to a Dilution Offering);

               (b) Except as  otherwise  provided  herein,  the General  Partner
          shall not at any time transfer or assign its interest or obligation as
          General Partner;

                  (c) The Partnership  Interest of any Limited Partner shall not
         be  transferred,  in whole or in part,  except in  accordance  with the
         conditions and limitations set forth in Articles 17.2 or 18;

                  (d) The  transferee of a Partnership  Interest by  assignment,
         operation of law or otherwise,  shall have only the rights,  powers and
         privileges  enumerated in Article 17.3 or otherwise provided by law and
         may not be admitted to the  Partnership as a Limited  Partner except as
         provided in Article 17.4 or as a General  Partner except as provided in
         Article 17.5;

               (e)  Notwithstanding  any provision  herein to the contrary,  the
          Partnership  Agreement  shall  in no  way  restrict  the  issuance  or
          transfers of stock of the General Partner; and

               (f)  Notwithstanding  any provision  herein to the contrary,  the
          issuance of Partnership  Interests pursuant to a Dilution Offering and
          the admission of new


                                                       -14-


<PAGE>



         Limited Partners  pursuant to a Dilution  Offering shall be governed by
         the provisions of Article 7.4 of this Agreement.

                  17.2     Restrictions on Transfers by Limited Partners.
                           ---------------------------------------------

                  (a) All or part of a Partnership  Interest may be  transferred
         by a  Limited  Partner  only  with the prior  written  approval  of the
         General  Partner,  which  approval may be granted or denied in the sole
         discretion of the General Partner.

                  (b) The General  Partner  shall not approve any  transfer of a
         Partnership  Interest,  except a pledge of any Partnership  Interest by
         the General Partner to any bank,  insurance  company or other financial
         institution to secure payment of indebtedness  (a "Permitted  Pledge"),
         or otherwise  unless the proposed  transferee  shall have furnished the
         General Partner with a sworn statement that:

                         (i) The proposed  transferee proposes to acquire his or
                    her Partnership Interest as a principal,  for investment and
                    not with a view to resale or distribution;

                           (ii) The proposed  transferee meets such requirements
                  regarding sophistication,  income and net worth as required by
                  applicable state and federal securities laws;

                           (iii) The proposed  transferee has met such net worth
                  and income  suitability  standards as have been established by
                  the General Partner;

                           (iv)  The   proposed   transferee   recognizes   that
                  investment in the Partnership  involves  certain risks and has
                  taken  full  cognizance  of and  understands  all of the  risk
                  factors related to the purchase of a Partnership Interest; and

                         (v)  The   proposed   transferee   has  met  all  other
                    requirements   of  the  General  Partner  for  the  proposed
                    transfer.

                  (c) Other than in the case of a Permitted  Pledge,  a transfer
         of a  Partnership  Interest  may be made  only  if,  prior  to the date
         thereof,  the Partnership  upon request receives an opinion of counsel,
         satisfactory in form and substance to the General Partner, that neither
         the offering nor the proposed transfer will require  registration under
         federal or applicable state securities laws or regulations.

     17.3 Rights of Transferee. Unless admitted to the Partnership in accordance
with Article 17.4, the transferee of a Partnership Interest or a part thereof or
any right, title or interest


                                                       -15-


<PAGE>



therein shall not be entitled to any of the rights, powers, or privileges of his
or her  predecessor in interest,  except that (s)he shall be entitled to receive
and be credited or debited with his or her  proportionate  share of  Partnership
income, gains, Profits, Losses, deductions, credits or distributions.

                  17.4  Admission  of  Limited  Partners.  Except  as  otherwise
provided in Article 18, the General Partner, or the transferee of all or part of
the Partnership  Interest of either a General Partner or a Limited Partner,  may
be admitted to the  Partnership  as a Limited  Partner  upon  furnishing  to the
General Partner all of the following:

                  (a) The  written  approval of a Majority in Interest of all of
         the Limited  Partners  (except the assignor  Partner),  or the assignor
         Partner  alone,  which  approval  may be  granted or denied in the sole
         discretion of such Partners or Partner (as the case may be);

               (b) The written approval of the General  Partner,  which approval
          may be  granted  or  denied  in the  sole  discretion  of the  General
          Partner;

                  (c) Acceptance, in a form satisfactory to the General Partner,
         of all the  terms  and  conditions  of  this  Agreement  and any  other
         documents  required in connection with the operation of the Partnership
         pursuant to the terms of this Agreement;

               (d) A properly executed power of attorney substantially identical
          to that contained in Article 38;

               (e) Such other  documents  or  instruments  as may be required in
          order to effect his or her admission as a Limited Partner; and

               (f)  Payment of such  reasonable  expenses  as may be incurred in
          connection with his or her admission as a Limited Partner.

     17.5 Admission of General Partners. A Limited Partner, or the transferee of
     all or part of the  Partnership  Interest  of the General  Partner,  may be
     admitted to the  Partnership  as a general  partner upon  furnishing to the
     General Partner all of the following:

                  (a) The  written  consent of both the  General  Partner  and a
         Majority  in Interest of the  Limited  Partners,  which  consent may be
         granted or denied in the sole discretion of the Partners;

                  (b) Such financial statements,  guarantees or other assurances
         as the General  Partner  may require  with regard to the ability of the
         proposed  general  partner to fulfill the  financial  obligations  of a
         general partner hereunder;


                                                       -16-


<PAGE>



                  (c) Acceptance,  in form  satisfactory to the General Partner,
         of all the  terms  and  provisions  of  this  Agreement  and any  other
         documents  required in connection with the operation of the Partnership
         pursuant to the terms of this Agreement;

               (d) A certified  copy of a  resolution  of its Board of Directors
          (if it is a corporation)  authorizing  it to become a general  partner
          under the terms and conditions of this Agreement;

               (e) A power of attorney substantially identical to that contained
          in Article 38;

               (f) Such other  documents  or  instruments  as may be required in
          order to effect its admission as a general partner; and

               (g)  Payment of such  reasonable  expenses  as may be incurred in
          connection with its admission as a general partner.

                  Notwithstanding  the above,  a transferee  that controls or is
controlled by the General Partner or one or more of its Affiliates that receives
all or part of the  Partnership  Interest of the General Partner may be admitted
to the  Partnership as a general  partner upon complying with all the provisions
of Article  17.5  except for  subparagraph  17.5(a).  As long as the  transferee
either  controls or is controlled  by the General  Partner or one or more of its
Affiliates,  no  Limited  Partner  consents  will  be  required  to  admit  such
transferee as a general partner to the Partnership.

                  17.6  Amendment  of  Certificate  of Limited  Partnership  and
Qualification.   The  General   Partner  shall  take  all  steps  necessary  and
appropriate to prepare and record any  amendments to the  Certificate of Limited
Partnership, as may be necessary or appropriate from time to time to comply with
the requirements of the Act, including,  without limitation,  upon the admission
to the Partnership of any general partner  pursuant to the provisions of Article
17.5, and may for this purpose  exercise the power of attorney  delivered to the
General Partner pursuant to Article 17.5 or 38. In addition, the General Partner
shall take all steps necessary and appropriate to prepare and record any and all
documents  necessary to qualify the Partnership to do business in  jurisdictions
where the Partnership is doing business,  and may for this purpose  exercise the
power of attorney  delivered to the General  Partner  pursuant to Articles 17.4,
17.5 or 38.

                  17.7 Fundamental  Changes.  In the event a plan is approved by
the General Partner and a Majority in Interest of the Limited Partners providing
for the  merger or  consolidation  of the  Partnership  with  another  person or
entity,  or the sale of all or substantially  all of the Partnership  Interests,
including  without  limitation the exchange of Partnership  Interests for equity
interests  in  another  person or entity or for cash or other  consideration  or
combination  thereof,  then and in such  event,  the Limited  Partners  shall be
obligated to take or refrain  from  taking,  as the case may be, such actions as
the plan may provide, including, without limitation, executing such instruments,
and


                                                       -17-


<PAGE>



providing such information as the General Partner shall reasonably request.  Any
plan  described  in this  Article  17.7  may also  effect  an  amendment  to the
Partnership Agreement or the adoption of a new partnership agreement as provided
in Section  15678.2(e)  of the Act.  The plan may also  provide that the General
Partner  and  its  Affiliates  shall  receive  fees  for  services  rendered  in
connection  with  the  operation  of the  Partnership  or any  successor  entity
following  the  consummation  of the  transactions  described  in the plan,  and
neither the  Partnership nor the Partners shall have any right by virtue of this
Agreement in the income derived therefrom. Any securities or other consideration
to be distributed  to the Partners  pursuant to the plan shall be distributed in
the  manner  set forth in Article  25(c) as though  the  Partnership  were being
liquidated.  For this purpose only,  the fair market value of the  securities or
other  consideration  to be  received  pursuant  to the plan shall be treated as
"Profits"  and the capital  accounts of the  Partners  shall be increased in the
manner  provided  in Article  12(a)(ii).  No Partner  shall be  entitled  to any
dissent,  appraisal or similar rights in connection with a plan  contemplated by
this Article 17.7.

                  17.8 Withdrawal of Initial Limited Partner.  Upon the date the
first Limited  Partner is admitted to the Partnership in accordance with Article
11 of this  Agreement,  the Initial  Limited  Partner  shall  withdraw  from the
Partnership,  and thereupon his Capital  Contribution  shall be returned and his
Partnership Interest canceled and reallocated to the Limited Partners.

                  18.      OPTIONAL PURCHASE OF LIMITED PARTNERSHIP INTERESTS
                           --------------------------------------------------
                           ON CERTAIN EVENTS.
                           -----------------

                  18.1 Death. Upon the death of a Limited Partner,  the deceased
Limited  Partner's   executor,   administrator,   or  other  legal  or  personal
representative  shall give written  notice of that fact to the General  Partner.
The General Partner shall have the option to purchase at the Closing (as defined
below) the Partnership Interest of the deceased Limited Partner (whose executor,
administrator  or other  legal or  personal  representative  shall  then  become
obligated  to sell such  Partnership  Interest) at the price  determined  in the
manner  provided  in  Article  18.7  of  this  Agreement  and on the  terms  and
conditions provided in Article 18.8 of this Agreement. The General Partner shall
have a period of thirty (30) days  following  the date of notice of the death of
the Limited Partner (the "Option  Period") within which to notify in writing the
deceased Limited  Partner's  executor,  administrator or other legal or personal
representative,  whether the General Partner wishes to purchase all or a portion
of the  Partnership  Interest of the deceased  Limited  Partner.  If the General
Partner  does not elect to  purchase  the  entire  Partnership  Interest  of the
deceased  Limited  Partner before the expiration of the Option Period and in the
manner provided  herein,  the portion of the Partnership  Interest not purchased
shall be held by the deceased Limited Partner's executor, administrator or other
legal  representative  pursuant  to the  terms of this  Agreement.  The  General
Partner, in its sole discretion,  may elect to assign its rights to purchase the
Partnership  Interest of the deceased Limited Partner under this Article 18.1 to
the Partnership and, in such case, the Partnership shall have the same rights as
provided for the General Partner in this Article 18.1.

     18.2  Bankruptcy,  Insolvency or  Assignment  for Benefit of Creditors of a
Limited Partner. In the event that an involuntary or voluntary  proceeding under
the Federal Bankruptcy



                                                       -18-


<PAGE>



Code, as amended, is filed for or against any Limited Partner, or if any Limited
Partner shall make an  assignment  for the benefit of his  creditors,  or if any
Limited  Partner has a receiver or custodian  appointed  for his assets,  or any
Limited Partner generally fails to pay his debts when due, the insolvent Limited
Partner shall give written  notice (the "Notice of  Insolvency")  to the General
Partner of the  commencement  of any such  proceeding or the  occurrence of such
event  within  five days of the  first  notice  to him of such  commencement  or
occurrence of such event.  The General Partner shall have the option to purchase
at the Closing  (as defined  below) the  Partnership  Interest of the  insolvent
Limited Partner (which the insolvent Limited Partner or his trustee,  custodian,
receiver or other  personal or legal  representative,  as the case may be, shall
then become obligated to sell) at the price determined in the manner provided in
Article  18.7 of this  Agreement  and on the terms and  conditions  provided  in
Article  18.8 of this  Agreement.  The  General  Partner  shall have a period of
thirty (30) days  following  the date of the Notice of  Insolvency  (the "Option
Period") within which to notify in writing the insolvent  Limited Partner or his
trustee, custodian, receiver, or other legal or personal representative, whether
the  General  Partner  wishes to  purchase  all or a portion of the  Partnership
Interest of the insolvent Limited Partner. If the General Partner does not elect
to purchase the entire  Partnership  Interest of the insolvent  Limited  Partner
before the  expiration of the Option Period and in the manner  provided  herein,
the  portion of the  Partnership  Interest  not  purchased  shall be held by the
insolvent Partner, his trustee,  custodian,  receiver or other legal or personal
representative pursuant to the terms of this Agreement.  The General Partner, in
its sole discretion,  may elect to assign its rights to purchase the Partnership
Interest  of an  insolvent  Limited  Partner  under  this  Article  18.2  to the
Partnership  and, in such case,  the  Partnership  shall have the same rights as
provided for the General Partner in this Article 18.2.

                  18.3 Breach of Article 15.3. In the event the General  Partner
either  receives a Notice of  Withdrawal as provided in Article 15.3 or receives
notice of a breach of Article 15.3 by or with respect to a Limited  Partner (the
"Competing  Limited  Partner"),  the  General  Partner  may  elect,  in its sole
discretion,  to treat such event as a default  under this  Agreement and enforce
the  provisions of this Article 18.3. If the General  Partner  elects to enforce
the  provisions  of this Article  18.3,  the General  Partner shall give written
notice of such  election  (the  "Notice of Default")  to the  Competing  Limited
Partner  within 180 days of the date the  General  Partner  first  received  the
Notice of  Withdrawal or notice of the  defaulting  event.  The General  Partner
shall  have the  option to  purchase  at the  Closing  (as  defined  below)  the
Partnership  Interest of the  Competing  Limited  Partner  (which the  Competing
Limited Partner shall then become  obligated to sell) at the price determined in
the manner  provided  in  Article  18.7 of this  Agreement  and on the terms and
conditions provided in Article 18.8 of this Agreement. The General Partner shall
have a period of  thirty  (30) days  following  the date it sends the  Notice of
Default (the "Option  Period")  within which to notify in writing the  Competing
Limited Partner,  whether the Partnership wishes to purchase all or a portion of
the  Partnership  Interest  of the  Competing  Limited  Partner.  If the General
Partner  does not elect to  purchase  the  entire  Partnership  Interest  of the
Competing  Limited Partner before the expiration of the Option Period and in the
manner provided  herein,  the portion of the Partnership  Interest not purchased
shall be held by the  Competing  Limited  Partner  pursuant to the terms of this
Agreement. The General Partner, in its sole discretion,  may elect to assign its
rights to purchase the Partnership


                                                       -19-


<PAGE>



Interest  of a  Competing  Limited  Partner  under  this  Article  18.3  to  the
Partnership  and, in such case,  the  Partnership  shall have the same rights as
provided for the General Partner in this Article 18.3.

                  18.4  Domestic  Proceeding.  In the  event  that a spouse of a
Limited Partner  commences  against a Limited  Partner,  or a Limited Partner is
named in, a Domestic  Proceeding,  the Limited Partner shall give written notice
(the "Notice of Domestic Proceeding") to the General Partner of the commencement
of any such  proceeding  within  five  days of the  first  notice to him of such
commencement.  The  General  Partner  shall have the option to  purchase  at the
Closing  (as defined  below) the  Partnership  Interest  of the Limited  Partner
involved in the Domestic Proceeding (which the Limited Partner shall then become
obligated to sell),  at the price  determined in the manner  provided in Article
18.7 of this Agreement and on the terms and conditions  provided in Article 18.8
of this  Agreement.  The General Partner shall have a period of thirty (30) days
following the date of the Notice of Domestic  Proceeding  (the "Option  Period")
within which to notify in writing the Limited  Partner  involved in the Domestic
Proceeding,  whether the General  Partner wishes to purchase all or a portion of
the Partnership  Interest of such Limited  Partner.  If the General Partner does
not elect to purchase the Partnership  Interest of the Limited Partner  involved
in the Domestic Proceeding before the expiration of the Option Period and in the
manner provided  herein,  the portion of the Partnership  Interest not purchased
shall be held by such Limited  Partner  pursuant to the terms of this Agreement.
The General Partner,  in its sole discretion,  may elect to assign its rights to
purchase  the  Partnership  Interest  of the  Limited  Partner  involved  in the
Domestic  Proceeding  under this  Article 18.4 to the  Partnership  and, in such
case,  the  Partnership  shall have the same rights as provided  for the General
Partner in this Article 18.4.

                  18.5 Divestiture  Option.  If state or federal  regulations or
laws are enacted or applied, or if any other legal developments occur, which, in
the opinion of the General Partner  adversely  affect (or potentially  adversely
affect) the operation of the Partnership  (e.g., the enactment or application of
prohibitory physician  self-referral  legislation against the Partnership or its
Partners),  the General Partner shall promptly  either,  in its sole discretion,
(i) take the steps outlined in this Article 18.5 to divest the Limited  Partners
of their Partnership Interests,  or (ii) dissolve the Partnership as provided in
Article  24.1(e).  If the General Partner chooses option (i), it shall deliver a
written  notice to all of the Limited  Partners (the "Notice of  Election")  and
purchase such Partnership  Interests for its own account.  The purchase price to
be paid for each  Partnership  Interest  shall be  determined  in the  manner as
provided in Article 18.7 and shall be on the terms and conditions as provided in
Article  18.8.  The transfer of the  Partnership  Interests,  the payment of the
purchase price and the  assumption of the Limited  Partners'  obligations  under
their respective  Guaranties (as provided in Article 18.7) shall be made at such
time as  determined  by the General  Partner to be in the best  interests of the
Partnership  and its  Limited  Partners.  Each  Limited  Partner  hereby  makes,
constitutes and appoints the General  Partner,  with full power of substitution,
his true and lawful  attorney-in-fact,  to take such  actions and  execute  such
documents  on his behalf to effect the transfer of his  Partnership  Interest as
provided in this Article  18.5.  The  foregoing  power of attorney  shall not be
affected by the  subsequent  incapacity,  mental  incompetence,  dissolution  or
bankruptcy of any Limited Partner.


                                                       -20-


<PAGE>



                  18.6  Default  under  Guaranties.  Notwithstanding  any  other
provision in this Article 18 to the contrary,  if any of the events  outlined in
Articles  18.1 or 18.2 or any other  defaulting  event  outlined in the Guaranty
(the  "Defaulting  Events")  should occur with respect to a Limited Partner (the
"Defaulting  Limited Partner"),  and the General Partner determines (in its sole
discretion)  that  such  event may  result in  default  and  acceleration  of an
obligation  secured by the Guaranty unless another  guarantor  acceptable to the
Lender can be substituted in the place of the Defaulting  Limited Partner,  then
the  General  Partner  shall  have the  right to  immediately  take the steps as
outlined in this Article 18.6 to prevent such default.  Upon the General Partner
receiving  notice of a Defaulting  Event as provided above, the General Partner,
in its sole discretion,  shall immediately have the right to either (i) sell the
entire  Partnership  Interest of the Defaulting  Limited  Partner to an investor
approved of by the General Partner, (ii) purchase for its own account the entire
Partnership Interest of the Defaulting Limited Partner, or (iii) sell the entire
Partnership  Interest of the  Defaulting  Limited  Partner to one or more of the
other Limited  Partners.  The Defaulting  Limited  Partner shall sell his or her
Partnership  Interest to the purchaser at the purchase  price  determined in the
manner as provided in Article 18.7 and on the terms and  conditions  as provided
in Article 18.8. The transfer of the  Partnership  Interest,  the payment of the
purchase  price,  and  the  assumption  of  the  Defaulting   Limited  Partner's
obligations  under his or her Guaranty (as provided in Article  18.7),  shall be
made at such time as  determined  by the  General  Partner in order to avoid the
default and acceleration of the obligation secured by the Guaranty. Each Limited
Partner hereby makes,  constitutes and appoints the General  Partner,  with full
power of substitution, his or her true and lawful attorney-in-fact, to take such
actions and execute  such  documents on his or her behalf to effect the transfer
of his or her  Partnership  Interest as provided in this  Article  18.6,  in the
event such Limited Partner becomes a Defaulting Limited Partner.

                  18.7  Purchase  Price.  The purchase  price to be paid for the
Partnership  Interest of any Limited  Partner whose interest is being  purchased
pursuant to the provisions of Articles 18.1, 18.2, 18.3, 18.4, 18.5 or 18.6 (the
"Selling  Limited  Partner")  shall be determined in the manner provided in this
Article 18.7. The purchase price for a Partnership  Interest  purchased pursuant
to the provisions of Article 18.1 shall be an amount equal to the greater of (i)
one and one-half  (1.5) times the aggregate  distributions  made with respect to
such  Partnership  Interest  pursuant to Article  14(a) during the  twelve-month
period  ending on the  Valuation  Date (as defined  below),  or (ii) the Selling
Limited Partner's share of the Partnership's book value determined in the manner
described  below.  The  purchase  price  for a  Partnership  Interest  purchased
pursuant to the provisions of Articles 18.2,  18.3,  18.4, 18.5 or 18.6 shall be
an  amount  equal to the  lesser  of (i) the fair  market  value of the  Selling
Limited  Partner's  Partnership  Interest on the Valuation Date (prorated in the
event that only a portion of his or her Partnership Interest is being purchased)
as  determined  by an  Appraiser  (as  defined  below)  selected  by the General
Partner,  or (ii) the Selling Limited Partner's share of the Partnership's  book
value,  if any  (prorated  in  the  event  that  only  a  portion  of his or her
Partnership  Interest is being purchased) as reflected by the Capital Account of
the Selling  Limited  Partner  (unadjusted  for any  appreciation in Partnership
assets and as reduced by depreciation  deductions claimed by the Partnership for
tax purposes) as of the Valuation Date (as defined below).  The General Partner,
in its sole  discretion,  may pursue  both of the above  valuation  methods  and
choose the lesser  value of the two as indicated  above,  or may  designate  and
follow only one of the methods in calculating the purchase  price.  For purposes
of this Article 18.7, the term "Appraiser" shall mean


                                                       -21-


<PAGE>



an  independent  appraiser  who is qualified in appraising  limited  partnership
interests and who has at least five years experience. In determining fair market
value, the Appraiser shall take into consideration any outstanding indebtedness,
liabilities,   liens  and  obligations  of  the  Partnership  and  the  relative
Partnership  Interests and capital accounts of all Partners, as well as applying
any customary discounts for lack of liquidity and control.  Such appraisal shall
be conducted in accordance with professional appraisal standards.  The valuation
of the  Appraiser  shall be  conclusive  and binding upon the  Partnership,  the
purchaser and the Selling  Limited Partner and his or her  representatives.  The
determination  of the Selling  Limited  Partner's  Capital  Account or aggregate
distributable  amount on the Valuation  Date (as defined below) shall be made by
the  Partnership's  internal  accountant (the  "Partnership  Accountant") upon a
review of the  Partnership  books of account,  and a formal  audit is  expressly
waived. The statement of the Partnership  Accountant with respect to the Capital
Account or aggregate  distributable amount of the Selling Limited Partner on the
Valuation  Date  shall be  binding  and  conclusive  upon the  Partnership,  the
purchaser and the Selling  Limited Partner and his or her  representatives.  The
Valuation Date means the last day of the month  immediately  preceding the month
in which occurs:  (i) the death of a Selling Limited  Partner,  in the case of a
purchase by reason of death;  (ii) the  bankruptcy  or  insolvency  of a Selling
Limited  Partner,  in the case of a  purchase  by reason of such  bankruptcy  or
insolvency; (iii) the Notice of Withdrawal or breach of Article 15.3 as provided
in  Article  18.3  in the  case  of a  purchase  by  reason  thereof;  (iv)  the
commencement  of the  Domestic  Proceeding,  in the case of a purchase by reason
thereof;  (v) the Notice of Election as provided in Article 18.5, in the case of
a purchase by reason thereof; or (vi) the notice of Defaulting Event as provided
in Article  18.6,  in the case of a purchase  occurring by reason of one of such
events. Any Limited Partner whose Partnership  Interest is purchased pursuant to
the provisions of Article 18.1, 18.2, 18.3, 18.4, 18.5 or 18.6 shall be entitled
only to the  purchase  price  which  shall be paid at the Closing in cash (or by
certified  or  cashier's  check) and shall not be  entitled  to any  Partnership
distributions  made after the  Valuation  Date. If as of the date of the Closing
the Selling Limited Partner still has an outstanding  personal  obligation under
the Guaranty (the  "Obligation"),  the purchaser shall assume the portion of the
Obligation  as is  equal  to the  portion  of  the  Partnership  Interest  being
purchased,  indemnify  the  Selling  Limited  Partner  from such  portion of the
Obligation,  and take such steps  deemed  necessary  by the  General  Partner to
formally  evidence the assumption of such portion of the  Obligation,  including
without  limitation,  executing  such  documents  and providing  such  financial
information  to the Bank to  evidence  the  assumption  of such  portion  of the
Obligation,  and obtain if possible,  the release of the Selling Limited Partner
from such portion of the Obligation. The transfer of a Partnership Interest of a
Selling  Limited  Partner shall be deemed to occur as of the Valuation  Date and
the Selling  Limited  Partner  shall have no voting or other rights as a Limited
Partner after such date.  The purchaser  shall be entitled to any  distributions
attributable  to the  transferred  interest  after  the  Valuation  Date and the
Partnership shall have the right to deduct the amount of any such  distributions
made to the Selling  Limited  Partner after the Valuation Date from the purchase
price.  Notwithstanding  the above,  the  Partnership  shall not be obligated to
assume any outstanding personal obligation of a Selling Limited Partner.


                                                       -22-


<PAGE>



                  18.8     Closing.
                           -------

                  18.8.1  Closing  of  Purchase  and Sale.  The  Closing  of any
         purchase and sale of a Partnership  Interest  pursuant to Article 18.1,
         18.2,  18.3,  18.4 or 18.5 of this  Agreement  shall  take place at the
         principal office of the Partnership,  or such other place designated by
         the General Partner, on the date determined as follows (the "Closing"):

                  (a) In the case of a purchase and sale  occurring by reason of
         the death of a Limited  Partner as  provided  in  Article  18.1 of this
         Agreement,  the Closing  shall be held on the thirtieth day (or if such
         thirtieth  day is not a business  day, the next  business day following
         the thirtieth day) next following the last to occur of:

                         (i)   Qualification   of  the   executor   or  personal
                    administrator of the deceased Limited Partner's estate;

                         (ii) The date on which any necessary  determination  of
                    the  purchase  price  of  the  Partnership  Interest  to  be
                    purchased has been made; or

                         (iii)  The date  that  coincides  with the close of the
                    Option Period.

                  (b) In the case of a purchase and sale  occurring by reason of
         the  occurrence of one of the events  described in Article 18.2,  18.3,
         18.4 or  18.5  of this  Agreement,  the  Closing  shall  be held on the
         thirtieth day (or if such thirtieth day is not a business day, the next
         business day following the thirtieth  day) next  following the later to
         occur of:

                         (i) The date on which any  necessary  determination  of
                    the  purchase  price  of  the  Partnership  Interest  to  be
                    purchased has been made; or

                         (ii)  The date  that  coincides  with the  close of the
                    Option Period.

         At the Closing,  although not  necessary  to effect the  transfer,  the
         Selling Limited Partner shall  concurrently  with tender and receipt of
         the applicable  purchase price,  deliver to the purchaser duly executed
         instruments of transfer and  assignment,  assigning good and marketable
         title to the  portion or  portions  of the  Selling  Limited  Partner's
         entire  Partnership  Interest thus  purchased,  free and clear from any
         liens  or  encumbrances  or  rights  of  others  therein.  The  parties
         acknowledge  that occurrence of any of the triggering  events described
         in Article 18.1, 18.2, 18.3, 18.4, 18.5 or 18.6


                                                       -23-


<PAGE>



         and  compliance  with all the  Articles of this  Agreement,  except the
         execution of the transfer  documents by the Selling  Limited Partner as
         provided  above in this Article  18.8.1,  are  sufficient to effect the
         complete transfer of the Selling Limited Partner's Partnership Interest
         and the Selling Limited Partner shall be deemed to consent to admission
         of the transferee as a substitute Limited Partner.  Notwithstanding the
         date of the  Closing  or whether a Closing is  successfully  held,  the
         transfer of a Partnership  Interest of a Selling  Limited Partner shall
         be deemed to occur as of the Valuation Date as defined in Article 18.7.
         The deemed  transfer  is  effective  regardless  of whether the Selling
         Limited Partner performs the duties set forth in this Article 18.8.1.

                  18.8.2  Terms and  Conditions  of  Purchase.  The  Partnership
         Interest of a Limited  Partner shall not be  transferred to any Partner
         unless the  requirements  of Articles 17.2 and 17.4 (b) through (f) are
         satisfied  with  respect to it. The  purchaser  shall be liable for all
         obligations  and  liabilities   connected  with  that  portion  of  the
         Partnership  Interest  transferred  to it  unless  otherwise  agreed in
         writing.

                  19.      SALE, ASSIGNMENT OR OTHER TRANSFER OF THE GENERAL
                           -------------------------------------------------
                           PARTNER'S INTEREST.
                           ------------------

                  19.1  The   General   Partner   may  not   mortgage,   pledge,
hypothecate,  transfer,  sell, assign or otherwise dispose of all or any part of
its interest in the  Partnership,  whether  voluntarily,  by operation of law or
otherwise (the foregoing  actions being  hereafter  collectively  referred to as
"Transfers" or singularly as a "Transfer") except as permitted by this Article.

                  19.2 If the  General  Partner  makes a Transfer  (other than a
mortgage,  pledge or  hypothecation)  of its  general  partner  interest  in the
Partnership pursuant to this Article, it shall be liable for all obligations and
liabilities  incurred  by it as the  general  partner of the  Partnership  on or
before  the  effective  date of such  Transfer,  but shall not be liable for any
obligations or liabilities of the  Partnership  arising after the effective date
of the Transfer.

          19.3 No Transfer by the General Partner shall be permitted unless:

                  (a) Counsel for the Partnership shall have rendered an opinion
         that none of the actions  taken in  connection  with such Transfer will
         cause the Partnership to be classified  other than as a partnership for
         federal   income  tax  purposes  or  will  cause  the   termination  or
         dissolution of the Partnership under state law; and

                  (b) Such  documents  or  instruments,  in form  and  substance
         satisfactory to counsel for the  Partnership,  shall have been executed
         and  delivered  as may be  required  in the  opinion of counsel for the
         Partnership to effect fully any such Transfer.


                                                       -24-


<PAGE>



                  Notwithstanding the foregoing provisions of this Article 19.3,
the General  Partner may pledge its  interest  in the  Partnership  to any bank,
insurance   company  or  other  financial   institution  to  secure  payment  of
indebtedness.

                  20.      TERMINATION OF THE SERVICES OF THE GENERAL PARTNER.
                           --------------------------------------------------

                  If the General Partner shall be finally adjudged by a court of
competent  jurisdiction to be liable to the Limited  Partners or the Partnership
for any act of gross negligence or willful  misconduct in the performance of its
duties under the terms of this Agreement, the General Partner may be removed and
another  substituted  with the  consent  of all of the  Limited  Partners.  Such
consent  shall be evidenced  by a  certificate  of removal  signed by all of the
Limited Partners. In the event of removal, the new general partner shall succeed
to all of the powers, privileges and obligations of the General Partner, and the
General  Partner's  interest in the  Partnership  shall become that of a Limited
Partner,  and the General Partner shall maintain its same Percentage Interest in
the Partnership  notwithstanding  anything contained in the Act to the contrary.
In addition,  in the event of removal,  the new general  partner  shall take all
steps  necessary  and  appropriate  to prepare  and record an  amendment  to the
Certificate of Limited Partnership to reflect the removal of the General Partner
and the admission of such new general partner.

                  21.      MANAGEMENT AND OPERATION OF BUSINESS.
                           ------------------------------------

                  21.1 All  decisions  with  respect  to the  management  of the
business and affairs of the Partnership shall be made by the General Partner.

                  21.2 The General  Partner shall be under no duty to devote all
of its time to the business of the Partnership,  but shall devote only such time
as it deems  necessary  to conduct the  Partnership  business and to operate and
manage the Partnership in an efficient manner.

                  21.3 The  General  Partner may charge to the  Partnership  all
ordinary and necessary costs and expenses, direct and indirect,  attributable to
the activities,  conduct and management of the business of the Partnership.  The
costs and expenses to be borne by the  Partnership  shall  include,  but are not
limited to, all  expenditures  incurred in acquiring and financing the Equipment
or other Partnership property, legal and accounting fees and expenses,  salaries
of employees of the Partnership,  consulting and quality  assurance fees paid to
independent contractors, insurance premiums and interest.

                  21.4 In addition to, and not in limitation  of, any rights and
powers  covenanted by law or other  provisions of this Agreement,  and except as
limited,  restricted or prohibited by the express  provisions of this Agreement,
the General Partner shall have and may exercise on behalf of the Partnership all
powers and rights necessary,  proper,  convenient or advisable to effectuate and
carry out the purposes, business and objectives of the Partnership.  Such powers
shall include, without limitation, the following:


                                                       -25-


<PAGE>



               (a) To conduct the Offering  and any Dilution  Offering on behalf
          of the Partnership;

                  (b) To  acquire on behalf of the  Partnership  (i) one or more
         fixed  base  or  transportable   lithotripsy  systems,   including  the
         Lithotripter  System, (ii) any other assets related to the provision of
         lithotripsy  services,  or (iii) any other  assets or  equipment  or an
         interest  in  another  entity  consistent  with  the  purposes  of  the
         Partnership  as provided in Article 4  (collectively,  the  "Additional
         Assets"),  at such times and at such price and upon such terms,  as the
         General Partner deems to be in the best interest of the Partnership;

                  (c) To purchase,  hold, manage,  lease, license and dispose of
         Partnership assets, including the purchase,  exchange, trade or sale of
         the Partnership's assets at such price, or amount, for cash, securities
         or other property and upon such terms,  as the General Partner deems to
         be in the best interest of the Partnership;  provided,  that should the
         Partnership  assets be  exchanged  or traded  for  securities  or other
         property (the  "Replacement  Property") the General  Partner shall have
         the same  powers  with  regard to the  Replacement  Property as it does
         towards the traded property;

               (d)  To  exercise  the  option  of  the  General  Partner  or the
          Partnership  to  purchase  a Limited  Partner's  Partnership  Interest
          pursuant to Article 18;

               (e) To determine the travel  itinerary and site locations for the
          Lithotripter System or other Partnership technology;

                  (f) To borrow money for any Partnership purpose (including the
         acquisition  of the  Additional  Assets)  and,  if security is required
         therefor, to subject to any security device any portion of the property
         for the  Partnership,  to obtain  replacements  of any  other  security
         device, to prepay, in whole or in part,  refinance,  increase,  modify,
         consolidate or extend any encumbrance or other security device;

                  (g) To deposit,  withdraw,  invest, pay, retain (including the
         establishment  of reserves in order to acquire the  Additional  Assets)
         and distribute the  Partnership's  funds in any manner  consistent with
         the provisions of this Agreement;

                  (h)      To institute and defend actions at law or in equity;

                  (i) To enter into and carry out contracts and  agreements  and
         any or all documents and  instruments  and to do any and all such other
         things as may be in furtherance of Partnership purposes or necessary or
         appropriate to the conduct of the Partnership activities;


                                                       -26-


<PAGE>



               (j) To execute,  acknowledge  and deliver any and all instruments
          which may be deemed necessary or convenient to effect the foregoing;

                  (k) To engage or retain one or more persons to perform acts or
         provide  materials  as  may be  required  by  the  Partnership,  at the
         Partnership's  expense,  and to compensate  such person or persons at a
         rate to be set by the General  Partner,  provided that the compensation
         is at the then  prevailing  rate for the type of services and materials
         provided,  or both.  Any person,  whether a Partner,  an Affiliate of a
         Partner or otherwise, including without limitation the General Partner,
         may be employed or engaged by the  Partnership  to render  services and
         provide materials,  including, but not limited to, management services,
         professional   services,   accounting   services,   quality  assessment
         services, legal services,  marketing services,  maintenance services or
         provide materials; and if such person is a Partner or an Affiliate of a
         Partner, (s)he shall be entitled to, and shall be paid compensation for
         said services or materials,  anything in this Agreement to the contrary
         notwithstanding, provided that the compensation to be received for such
         services  or  materials  is  competitive  in price and terms  with then
         prevailing rate for the type of services and/or materials provided. The
         Partnership,  pursuant  to the terms of a  Management  Agreement,  will
         contract with Sun Medical Technologies,  Inc., a California corporation
         ("Sun") and the general partner of the General Partner, with respect to
         the supervision and  coordination of the management and  administration
         of the  day-to-day  operations  of  the  Partnership's  business  for a
         monthly fee equal to 7.5% of net Partnership  Cash Flow per month.  All
         costs incurred by Sun under the Management  Agreement  shall be paid or
         reimbursed  by the  Partnership  directly.  The  Partnership  may  also
         contract  with  healthcare   facilities  and/or  qualified   physicians
         desiring to use its Lithotripter  System for the treatment of patients.
         Owning an interest in the Partnership shall not be a condition to using
         the  Lithotripter  System.  The  General  Partner  and  its  Affiliates
         (including  Sun) may engage in or possess an interest in other business
         ventures of any nature and  description  independently  or with others,
         including,  but not limited to, the operation of a fixed-base or mobile
         lithotripsy  unit,  whether or not such business ventures are in direct
         or  indirect   competition  with  the  Partnership,   and  neither  the
         Partnership  nor the  Partners  shall  have any right by virtue of this
         Agreement  in and to said  independent  ventures  or to the  income  or
         profits derived therefrom.

                  21.5  In  addition  to  other  acts  expressly  prohibited  or
restricted  by this  Agreement  or by law,  the  General  Partner  shall have no
authority to act on behalf of the Partnership in:

                    (a) Doing any act in  contravention of this Agreement or the
               Partnership's Certificate of Limited Partnership;

                    (b) Doing any act which would make it impossible to carry on
               the ordinary business of the Partnership;



                                                       -27-


<PAGE>



                    (c)   Possessing   or  in  any  manner   dealing   with  the
               Partnership's property or assigning the rights of the Partnership
               in  the   Partnership's   property  for  other  than  Partnership
               purposes;

                    (d)  Admitting  a person as a Limited  Partner  or a General
               Partner except as provided in this Agreement; or

                  (e)  Performing  any act (other  than an act  required by this
         Agreement  or any act  taken  in good  faith  reliance  upon  counsel's
         opinion)  which  would,  at the time  such act  occurred,  subject  any
         Limited Partner to liability as a general partner in any jurisdiction.

                  22.      RESERVES.


                  The  General  Partner  may cause the  Partnership  to create a
reserve account to be used exclusively for repairs and acquisition of Additional
Assets and for any other valid Partnership  purpose.  The General Partner shall,
in its sole discretion, determine the amount of payments to such reserve.

                  23.      INDEMNIFICATION AND EXCULPATION OF THE GENERAL
                           PARTNER.

                  23.1 The General  Partner is accountable to the Partnership as
a fiduciary and consequently  must exercise good faith and integrity in handling
Partnership  affairs.  The  General  Partner  and its  Affiliates  shall have no
liability to the  Partnership  which arises out of any action or inaction of the
General Partner or its Affiliates if the General  Partner or its Affiliates,  in
good faith,  determined  that such course of conduct was in the best interest of
the Partnership and such course of conduct did not constitute  gross  negligence
or willful  misconduct  of the General  Partner or its  Affiliates.  The General
Partner and its Affiliates  shall be indemnified by the Partnership  against any
losses, judgments,  liabilities,  expenses and amounts paid in settlement of any
claims sustained by them in connection with the  Partnership,  provided that the
same were not the result of gross  negligence or willful  misconduct on the part
of the General Partner or its Affiliates.

                  23.2 The General Partner shall not be liable for the return of
the Capital Contributions of the Limited Partners, and upon dissolution, Limited
Partners shall look solely to the assets of the Partnership.

                  24.      DISSOLUTION OF THE PARTNERSHIP.

     24.1 The  Partnership  shall be dissolved and  terminated  and its business
wound up upon the occurrence of any one of the following events:

                  (a)      The expiration of its term on December 31, 2049;


                                                       -28-


<PAGE>



                  (b) The  filing  by, on  behalf  of, or  against  the  General
         Partner of any  petition or  pleading,  voluntary  or  involuntary,  to
         declare the General  Partner  bankrupt under any bankruptcy law or act,
         or the  commencement  in any  court  of any  proceeding,  voluntary  or
         involuntary,  to declare the General Partner insolvent or unable to pay
         its debts, or the appointment by any court or supervisory  authority of
         a  receiver,  trustee or other  custodian  of the  property,  assets or
         business of the General  Partner or the  assignment by it of all or any
         part of its  property or assets for the benefit of  creditors,  if said
         action,  proceeding  or  appointment  is  not  dismissed,   vacated  or
         otherwise terminated within ninety (90) days of its commencement;

               (c) The determination of the General Partner that the Partnership
          should be dissolved;

                  (d) The occurrence of an event described in a plan approved by
         the General Partner and a Majority in Interest of the Limited  Partners
         pursuant  to  Article  17.7   resulting  in  the   dissolution  of  the
         Partnership;

               (e)  The  election  of  the  General   Partner  to  dissolve  the
          Partnership  following the occurrence of an event described in Article
          18.5;

                  (f) Except as otherwise  provided in any plan  approved by the
         General  Partner and a Majority  in  Interest  of the Limited  Partners
         pursuant to Article 17.7,  the sale,  exchange or other  disposition of
         all or  substantially  all of the property of the  Partnership  without
         making provision for the replacement thereof;

                  (g)   The   dissolution,   retirement,   resignation,   death,
         disability  or legal  incapacity  of a general  partner,  and any other
         event  resulting in the  dissolution or termination of the  Partnership
         under the laws of the State of  California;  provided,  that the events
         described  in  Sections  15681(c)  and  (d) of the  Act or any  similar
         provisions of any successor  statute,  shall not work a dissolution  of
         the Partnership except as expressly provided in (b) above;

               (h) The election to dissolve the  Partnership  made by all of the
          Partners.

                  24.2  Notwithstanding  the  provisions  of Article  24.1,  the
Partnership   shall  not  be  dissolved  and  terminated  upon  the  retirement,
resignation,  bankruptcy,  assignment for the benefit of creditors, dissolution,
death,  disability or legal  incapacity of a general  partner,  and its business
shall continue  pursuant to the terms and conditions of this  Agreement,  if any
general partner or general partners remain  following such event;  provided that
such  remaining  general  partner or general  partners  are hereby  obligated to
continue the business of the  Partnership.  If no general  partner remains after
the  occurrence of such event,  the business of the  Partnership  shall continue
pursuant to the terms and conditions of this  Agreement,  if, within ninety (90)
days after the occurrence of such


                                                       -29-


<PAGE>



event,  a Majority  in  Interest  of the  Limited  Partners  agree in writing to
continue the business of the Partnership,  and, if necessary, to the appointment
of one or more persons or entities to be substituted as the general partner.  In
the event the Limited  Partners agree as provided above to continue the business
of the Partnership, the new general partner or general partners shall succeed to
all of the powers,  privileges and obligations of the General  Partner,  and the
General  Partner's  interest in the Partnership shall become a Limited Partner's
interest hereunder. Furthermore, in the event a remaining general partner or the
Limited  Partners,  as the case may be,  agree to continue  the  business of the
Partnership  as provided  herein,  the  remaining  general  partner or the newly
appointed  general partner or general  partners,  as the case may be, shall take
all steps  necessary and  appropriate  to prepare and record an amendment to the
Certificate of Limited  Partnership to reflect the  continuation of the business
of the  Partnership  and the  admission  of a new  general  partner  or  general
partners, if any.

                  25.      DISTRIBUTION UPON DISSOLUTION.

                  Upon the dissolution and termination of the  Partnership,  the
General Partner or, if there is none, a representative  of the Limited Partners,
shall  cause  the  cancellation  of the  Partnership's  Certificate  of  Limited
Partnership,  shall liquidate the assets of the Partnership, and shall apply and
distribute the proceeds of such liquidation in the following order of priority:

               (a) First,  to the  payment of the debts and  liabilities  of the
          Partnership, and the expenses of liquidation;

                  (b) Second,  to the creation of any reserves which the General
         Partner  (or such  representatives  of the Limited  Partners)  may deem
         reasonably  necessary  for the payment of any  contingent or unforeseen
         liabilities or obligations of the Partnership or of the General Partner
         arising out of or in connection  with the business and operation of the
         Partnership; and

                  (c) Third,  the balance,  if any,  shall be distributed to the
         Partners in accordance  with the  Partners'  positive  Capital  Account
         balances  after such  Capital  Accounts  are  adjusted  as  provided by
         Article 13, and any other  adjustments  required by the Final  Treasury
         Regulations  under Section 704(b) of the Code. Any general partner with
         a negative  Capital Account  following the  distribution of liquidation
         proceeds or the  liquidation  of its interest  must  contribute  to the
         Partnership  an amount  equal to such  negative  Capital  Account on or
         before the end of the Partnership's  taxable year (or, if later, within
         ninety days after the date of liquidation).  Any capital so contributed
         shall  be (i)  distributed  to those  Partners  with  positive  Capital
         Accounts until such Capital  Accounts are reduced to zero,  and/or (ii)
         used to discharge recourse liabilities.


                                                       -30-


<PAGE>



                  26.      BOOKS OF ACCOUNT, RECORDS AND REPORTS.

                  26.1 Proper and complete records and books of account shall be
kept by the General  Partner in which shall be entered fully and  accurately all
transactions  and such other matters relating to the  Partnership's  business as
are usually  entered  into  records and books of account  maintained  by persons
engaged  in  businesses  of a like  character.  The  books  and  records  of the
Partnership  shall be prepared  according to the accounting method determined by
the General Partner.  The Partnership's  fiscal year shall be the calendar year.
The books and  records  shall at all times be  maintained  at the  Partnership's
Records Office and shall be open to the reasonable inspection and examination of
the Partners or their duly authorized representatives during reasonable business
hours.

                  26.2 Within  ninety (90) days after the end of each Year,  the
General  Partner shall send to each person who was a Limited Partner at any time
during such year such tax information,  including,  without limitation,  Federal
tax Schedule K-1, as shall be reasonably  necessary for the  preparation by such
person of his federal  income tax return.  The  General  Partner  will also make
available to the Limited Partners any other information required by the Act.

                  26.3 The General  Partner shall maintain at the  Partnership's
Records  Office  copies of the  Partnership's  original  Certificate  of Limited
Partnership   and  any  certificate  of  amendment,   restated   certificate  or
certificate of cancellation with respect thereto and such other documents as the
Act shall require.  The General Partner will furnish to any Limited Partner upon
request or as  otherwise  required by law a copy of the  Partnership's  original
Certificate of Limited  Partnership and any  certificate of amendment,  restated
certificate, or certificate of cancellation, if any.

                  26.4 The General Partner shall, in its sole  discretion,  make
for the  Partnership  any and all  elections  for  federal,  state and local tax
purposes including, without limitation, any election, if permitted by applicable
law, to adjust the basis of the Partnership's property pursuant to Code Sections
754,  734(b) and  743(b),  or  comparable  provisions  of state or local law, in
connection  with  transfers  of  interests in the  Partnership  and  Partnership
Distributions.

                  26.5 The  General  Partner is  designated  as the Tax  Matters
Partner  (as  defined  in  Section  6231 of the Code) and to act in any  similar
capacity  under  state or local law,  and is  authorized  (at the  Partnership's
expense):   (i)  to  represent  the   Partnership  and  Partners  before  taxing
authorities  or courts of competent  jurisdiction  in tax matters  affecting the
Partnership  or  Partners  in their  capacity  as  Partners;  (ii) to extend the
statute of limitations for assessment of tax deficiencies  against Partners with
respect to adjustments to the Partnership's federal, state or local tax returns;
(iii) to execute any agreements or other documents relating to or affecting such
tax matters, including agreements or other documents that bind the Partners with
respect to such tax matters or  otherwise  affect the rights of the  Partnership
and Partners; and (iv) to expend Partnership funds for professional services and
costs  associated  therewith.  The General Partner is authorized and required to
notify the federal,  state or local tax  authorities of the appointment of a Tax
Matters  Partner  in  the  manner  provided  in  Treasury   Regulations  Section
301.6231(a)(7)-1, as modified from time to time. In its


                                                       -31-


<PAGE>



capacity  as  Tax  Matters  Partner,  the  General  Partner  shall  oversee  the
Partnership's  tax affairs in the manner which, in its best judgment,  is in the
interests of the Partners.

                  27.      NOTICES.

                  All notices under this Agreement shall be in writing and shall
be deemed to have been given when delivered  personally,  or mailed by certified
or registered mail, postage prepaid,  return receipt  requested.  Notices to the
General  Partner  shall be  delivered  at, or mailed to, its  principal  office.
Notices to the  Partnership  shall be delivered  at, or mailed to, its principal
office with a copy to each of its business offices.  Notice to a Limited Partner
shall be  delivered  to such  Limited  Partner,  or mailed  to the last  address
furnished  by him for such  purposes to the General  Partner.  Limited  Partners
shall give  notice of a change of address to the  General  Partner in the manner
provided in this Article.

                  28.      AMENDMENTS.


                  Subject to the  provisions  of Article 28, this  Agreement  is
subject to  amendment  only by  written  consent of the  General  Partner  and a
Majority in Interest of the Limited Partners;  provided, however, the consent of
the Limited Partners shall not be required if such amendments are ministerial in
nature and do not contravene the provisions of Article 29.  Further,  no Limited
Partner  consent shall be required to amend  Schedule A to reflect the admission
of  Partners  as  contemplated  by the  Offering,  any  Dilution  Offering or as
otherwise herein permitted.

                  29.      LIMITATIONS ON AMENDMENTS.
                           -------------------------

                  Notwithstanding  the provisions of Article 28, no amendment to
this Agreement shall:

                  (a)  Enlarge  the   obligations  of  any  Partner  under  this
         Agreement  or convert the  interest in the  Partnership  of any Limited
         Partner  into the  interest of a general  partner or modify the limited
         liability of any Limited Partner, without the consent of such Partner;

                  (b) Amend the  provisions  of Article 13, 14, 16 or 25 without
         the  approval of the General  Partner and a Majority in Interest of the
         Limited Partners;  provided,  however,  that the General Partner may at
         any time  amend  such  Articles  without  the  consent  of the  Limited
         Partners in order to permit the Partnership allocations to be sustained
         for federal  income tax  purposes,  but only if such  amendments do not
         materially  affect  adversely the rights and obligations of the Limited
         Partners, in which case such amendments may only be made as provided in
         this Article 29(b); or

               (c) Amend this Article 29 without the consent of all Partners.


                                                       -32-


<PAGE>



                  30.      MEETINGS, CONSENTS AND VOTING.
                           -----------------------------

                  30.1 A meeting of the  Partnership to consider any matter with
respect to which the  Partners  may vote as set forth in this  Agreement  may be
called  by the  General  Partner  or by  Limited  Partners  who hold  more  than
twenty-five  percent (25%) of the aggregate interests in the Partnership held by
all the Limited Partners.  Upon receipt of a notice requesting a meeting by such
Partner or Partners and stating the purpose of the meeting,  the General Partner
shall, within ten (10) days thereafter, give notice to the Partners of a meeting
of the  Partnership to be held at a time and place  generally  convenient to the
Limited  Partners on a date not earlier than fifteen (15) days after  receipt by
the  General  Partner of the  notice  requesting  a  meeting.  The notice of the
meeting shall set forth the time, date, location and purpose of the meeting.

     30.2 Any consent of a Partner  required by this  Agreement  may be given as
follows:

               (a) By a written  consent  given by the  consenting  Partner  and
          received by the General Partner at or prior to the doing of the act or
          thing for which the consent is solicited, or

                  (b) By the affirmative  vote by the consenting  Partner to the
         doing of the act or thing for which the  consent  is  solicited  at any
         meeting  called  pursuant to this Article to consider the doing of such
         act or thing.

                  30.3 When exercising voting rights expressly granted under the
Articles of this  Agreement,  each Partner shall have that number of votes as is
equal to the  Percentage  Interest  of such  Partner  at the  time of the  vote,
multiplied by 100.

                  31.      SUBMISSIONS TO THE LIMITED PARTNERS.
                           -----------------------------------

                  The General Partner shall give the Limited  Partners notice of
any proposal or other matter  required by any provision of this  Agreement or by
law to be submitted for consideration and approval of the Limited Partners. Such
notice shall include any  information  required by the relevant  provision or by
law.

                  32.      ADDITIONAL DOCUMENTS.
                           --------------------

                  Each  party  hereto  agrees to  execute  and  acknowledge  all
documents and writings which the General Partner may deem necessary or expedient
in the creation of this Partnership and the achievement of its purpose.

                  33.      SURVIVAL OF RIGHTS.
                           ------------------

                  Except as herein  otherwise  provided  to the  contrary,  this
Agreement  shall be binding upon and inure to the benefit of the parties hereto,
their successor and assigns.


                                                       -33-


<PAGE>



                  34.      INTERPRETATION AND GOVERNING LAW.
                           --------------------------------

                  When the  context  in which  words are used in this  Agreement
indicates  that such is the intent,  words in the singular  number shall include
the plural and vise versa; in addition,  the masculine  gender shall include the
feminine and neuter  counterparts.  The Article headings or titles and the table
of  contents  shall not define,  limit,  extend or  interpret  the scope of this
Agreement  or any  particular  Article.  This  Agreement  shall be governed  and
construed in accordance with the laws of the State of California  without giving
effect to the conflicts of laws provisions thereof.

                  35.      SEVERABILITY.
                           ------------

                  If any provision,  sentence,  phrase or word of this Agreement
or the application  thereof to any person or circumstance shall be held invalid,
the remainder of this Agreement, or the application of such provision, sentence,
phrase, or word to persons or circumstances,  other than those as to which it is
held invalid, shall not be affected thereby.

                  36.      AGREEMENT IN COUNTERPARTS.
                           -------------------------

                  This Agreement may be executed in several  counterparts,  each
of which shall be deemed an original,  but all of which shall constitute one and
the same  instrument.  In  addition,  this  Agreement  may contain more than one
counterpart  of the  signature  page and this  Agreement  may be executed by the
affixing of the  signatures  of each of the Partners to one of such  counterpart
signature  pages;  all of such signature  pages shall be read as though one, and
they  shall have the same  force and  effect as though  all of the  signers  had
signed a single signature page.

                  37.      THIRD PARTIES.
                           -------------

                  The agreements, covenants and representations contained herein
are for the benefit of the parties  hereto  inter se and are not for the benefit
of any  third  parties  including,  without  limitation,  any  creditors  of the
Partnership.

                  38.      POWER OF ATTORNEY.
                           -----------------

                  Each Limited  Partner hereby makes,  constitutes  and appoints
Stan Johnson and Cheryl  Williams,  severally,  with full power of substitution,
his true and lawful attorneys-in-fact,  for him and in his name, place and stead
and for his use and  benefit  to sign  and  acknowledge,  file and  record,  any
amendments  hereto among the Partners for the further  purpose of executing  and
filing on behalf of each Limited  Partner,  any and all  certificates of limited
partnership or other  documents  necessary to constitute  the  Partnership or to
effect the  continuation  of the  Partnership,  the admission or withdrawal of a
general partner or a limited partner,  the qualification of the Partnership in a
foreign  jurisdiction  (or  amendment to such  qualification),  the admission of
substitute   Limited   Partners  or  the   dissolution  or  termination  of  the
Partnership, provided such continuation,  admission, withdrawal,  qualification,
or  dissolution  and  termination  are in  accordance  with  the  terms  of this
Agreement.


                                                       -34-


<PAGE>



                  The foregoing power of attorney is a special power of attorney
coupled with an interest,  is  irrevocable  and shall  survive the death,  legal
incapacity,  dissolution  or  bankruptcy  of  each  Limited  Partner.  It may be
exercised by any one of said  attorneys  by listing all of the Limited  Partners
executing any instrument over the signature of the  attorney-in-fact  acting for
all of them.  The power of attorney  shall survive the delivery of an assignment
by a Limited  Partner of the whole or any portion of his Unit. In those cases in
which the assignee of, or the successor to, a Limited  Partner owning a Unit has
been approved by the Partners for admission to the  Partnership  as a substitute
Limited  Partner,  the power of attorney  shall  survive for the sole purpose of
enabling the General  Partner to execute,  acknowledge  and file any  instrument
necessary to effect such substitution.

                  This power of attorney shall not be affected by the subsequent
bankruptcy,  dissolution,  incapacity  or  mental  incompetence  of any  Limited
Partner.

                  39.      ARBITRATION.
                           -----------

                  Any  dispute  arising  out  of  or  in  connection  with  this
Agreement or the breach thereof shall be decided by arbitration in Austin, Texas
in  accordance  with  the then  effective  commercial  arbitration  rules of the
American  Arbitration  Association,  and judgment  thereof may be entered in any
court having jurisdiction thereof.

                  40.      CREDITORS.
                           ---------

                  None of the  provisions  of this  Agreement  shall  be for the
benefit of or enforceable by any creditors of the Partnership.

                                             [signature page follows]



                                                       -35-


<PAGE>




                  IN WITNESS  WHEREOF,  the parties have executed this Agreement
of Limited Partnership as of the day and year first above written.

                           GENERAL PARTNER:

                           MOBILE KIDNEY STONE CENTERS OF

                           CALIFORNIA, LTD., a California limited
                               partnership

                           By:      Sun Medical Technologies, Inc., a California
                                    Corporation and its sole general partner



                           By:  /s/ Stan Johnson
                           ---------------------
                                Stan Johnson
                                President


ATTEST:

/s/ Vincent Prendergast                                        [CORPORATE SEAL]
- -----------------------
Secretary

                                  INITIAL LIMITED PARTNER:
                                  -----------------------

                                  /s/ Stan Johnson
                                  ----------------
                                  Stan Johnson


                                                       -36-


<PAGE>




STATE OF North Carolina

COUNTY OF Cumberland

     On this 31 day of March,  1999, before me, the undersigned Notary Public in
and for the County of Cumberland in the State of North Carolina, personally came
Stan  Johnson,  who,  being by me duly sworn,  said that he is  President of Sun
Medical  Technologies,  Inc.,  the sole general  partner of Mobile  Kidney Stone
Centers of  California,  Ltd.,  the sole general  partner of Mobile Kidney Stone
Centers  of  California  II,  L.P.,  that  the  seal  affixed  to the  foregoing
instrument in writing is the corporate  seal of the  corporation,  and that said
writing was signed, sworn to, and sealed by him in behalf of said corporation by
its authority duly given. And the said Stan Johnson,  further certified that the
facts set forth in said  writing are true and  correct,  and  acknowledged  said
instrument to be the act and deed of said corporation.

                  WITNESS my hand and notarial seal.

                                    /s/ Debra J. Scott
                                    ------------------
                                    Notary Public

My commission expires:
May 1, 1999

STATE OF North Carolina

COUNTY OF Cumberland


                  I, Debra J. Scott, a notary public in and for
the State and  County  set forth  above,  do hereby  certify  that Stan  Johnson
personally appeared before me this 31 day of March, 1999 and acknowledged
and swore to the due execution of the foregoing Limited Partnership Agreement in
his capacity as the initial limited partner.

                                    /s/ Debra J. Scott
                                    ------------------
                                    Notary Public

My commission expires:
May 1, 1999




                                                       -37-


<PAGE>



                           COUNTERPART SIGNATURE PAGE

                  By signing this  Counterpart  Signature  Page, the undersigned
acknowledges  his or  her  acceptance  of  that  certain  Agreement  of  Limited
Partnership  of Mobile Kidney Stone Centers of California  II, L.P.,  and his or
her intention to be legally bound thereby.

                  Dated this _________ day of ___________________, 1999.




                                    Signature


                                    Printed Name

STATE OF _______________                    )
                                            )
COUNTY OF _____________                     )


                  BEFORE ME, the undersigned  Notary Public in and for the State
and County set forth  above,  on the  _______ day of  __________________,  1999,
personally  appeared  ___________________,  and,  being by me first duly  sworn,
stated that (s)he  signed this  Counterpart  Signature  Page for the purpose set
forth above and that the statements contained therein are true.


                           Signature of Notary Public


                             Printed Name of Notary

My Commission Expires:

- ---------------------------
[SEAL]


                                                       -38-


<PAGE>



                                   SCHEDULE A
                        Schedule of Partnership Interests

               MOBILE KIDNEY STONE CENTERS OF CALIFORNIA II, L.P.
               --------------------------------------------------
           CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND PERCENTAGE
           ----------------------------------------------------------
                                    INTERESTS

                                  Cash                               Percentage
                                Contribution      Guaranty(1)         Interest
                                ------------       --------          -----------
General Partner

Mobile Kidney Stone Centers
   Of California, Ltd. I

15195 National Avenue,
Suite 203
Los Gatos, CA 95032              $100,000.00      $194,850.00            40.0%
Limited Partners
Erik Birzgalis, M.D.
3637 Mission Avenue

Carmichael, CA 95608             $  9,750.00      $ 18,997.88             3.9%
Frederick Burrell, M.D.
3160 Folsom Boulevard
Sacramento, CA 95816             $  7,500.00      $ 14,613.75             3.0%
Capital Urology Medical Group, Inc.
2801 K Street, Suite 220
Sacramento, CA 95816             $  9,750.00      $ 18,997.88             3.9%
Jong Chen, M.D.
3941 J Street #366
Sacramento, CA 95819             $  7,500.00      $ 14,613.75             3.0%
David Couillard, M.D.
2801 K Street #205
Sacramento, CA 95816             $  9,750.00      $ 18,997.88             3.9%
Leonard Crawford, M.D.
2801 K Street #220
Sacramento, CA 95816             $  9,750.00      $ 18,997.88             3.9%
Kaushik DeSai, M.D.
1600 Creekside Drive, Suite 2700
Folsom, CA 95630                 $  9,750.00      $ 18,997.88             3.9%
Abdo Faddoul, M.D.
Two Medical Plaza #125
Roseville, CA 95661              $  7,500.00      $ 14,613.75             3.0%



                                                       -39-


<PAGE>


                                        Cash                          Percentage
Patricia Fone, M.D.
2 Medical Plaza #255
Roseville, CA 95661       $    9,750.00           $ 18,997.88               3.9%
Klumars Hekmat, M.D.
2801 K Street #220
Sacramento, CA 95816      $    9,750.00           $ 18,997.88               3.9%
William Hoch, M.D.
2020 Sutter Place #102
Davis, CA 95616           $    7,500.00           $ 14,613.75               3.0%
H. Setsup Masaki, M.D.
5252 Elvas Avenue
Sacramento, CA 95819      $    5,000.00           $  9,742.50               2.0%
Iraj Nabi, M.D.
3160 Folsom Boulevard

Sacramento, CA 95816      $    7,500.00           $ 14,613.75               3.0%
Brian Naftulin, M.D.
2801 K Street #220
Sacramento, CA 95816      $    5,000.00           $  9,742.50               2.0%
Peter Novick, M.D.
77 Scripps Drive #112
Sacramento, CA 95825      $    9,750.00           $ 18,997.88               3.9%
Gordon Quinones, M.D.
6401 Coyle Avenue, Suite 310
Carmichael, CA 95608      $    5,000.00           $  9,742.50               2.0%
Nicholas Simopoulos, M.D.
100 Fowler Way #5
Placerville, CA 95667     $    9,750.00           $ 18,997.88               3.9%
Robert Wright, M.D.
2801 K Street #205
Sacramento, CA 95816      $    9,750.00           $ 18,997.88               3.9%

TOTAL:                      $250,000.00           $487,125.00             100.0%

(1 )Represents the principal portion of each Partner's guaranty  obligation,  as
each Partner's  obligation under the Guaranty  includes not only principal,  but
also (as provided in the  Guaranty)  accrued and unpaid  interest,  late payment
penalties  and all  costs  incurred  by the  Bank in  collecting  any  defaulted
obligations.  The  principal  amount of the loan is up to $487,125.  The General
Partner will guarantee 40% of the Loan (up to a $194,850 principal  guaranty) as
provided in the Memorandum.  The Limited Partners will individually guarantee 1%
of the loan (up to a $4,871.25  principal  guaranty) for each unit  purchased as
provided in the Memorandum.


                                                       -40-


<PAGE>



                               FOURTH AMENDMENT TO
                       AGREEMENT OF LIMITED PARTNERSHIP OF
              LOUISIANA LITHOTRIPSY INVESTMENT LIMITED PARTNERSHIP


                  THIS AMENDMENT, effective as of the 1st day of April, 1999, is
entered into by and among Lithotripters,  Inc., a North Carolina corporation and
the General Partner of Louisiana Lithotripsy  Investment Limited Partnership,  a
North Carolina limited partnership (the "Partnership"), and the Limited Partners
of the Partnership.

                                R E C I T A L S:
                                 ---------------

                  1. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the  "Partners",  entered into that certain Amended
and  Restated  Agreement  of  Limited   Partnership  of  Louisiana   Lithotripsy
Investment Limited Partnership, dated as of October 30, 1989, as amended by that
certain First Amendment to Agreement of Limited  Partnership of the Partnership,
effective as of January 1, 1990, and as amended by that certain Second Amendment
to Agreement of Limited Partnership of the Partnership,  effective as of January
1, 1997, and as amended by that certain Third  Amendment to Agreement of Limited
Partnership of the Partnership,  effective as of July 1, 1998 (the  "Partnership
Agreement").

                  2. The  Partners  desire  to  further  amend  the  Partnership
Agreement to reflect the Partners's adjusted Percentage Interests resulting from
the  Partnership's  Dilution  Offering,  and  the  subsequent  admission  of the
following new Limited Partners to the Partnership; Christopher P. Fontenot, M.D.
(1.000%),  Gordon Sean Healey  (0.500%),  Brad Johnson  (1.000%),  Chuen K. Kwok
(1.000%),  Steven A. Socher  (1.000%),  Lance Templeton  (1.000%) and Kenneth S.
Verheeck (1.000%).

                  NOW,  THEREFORE,  in  consideration  of the  mutual  promises,
covenants,  conditions and agreements herein contained, the parties hereto agree
as follows:

                           Schedule  A-2 is  deleted in its  entirety  and a new
                           Schedule A-3,  attached hereto, is substituted in its
                           place.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first above written.

                                                     GENERAL PARTNER:

                                                     Lithotripters, Inc.


                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                            Joseph Jenkins, M.D.
                                                            President





<PAGE>



                                                     ALL THE LIMITED PARTNERS OF
                                                     THE PARTNERSHIP WHOSE NAMES
                                                     APPEARED ON SCHEDULE A-3

                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                            Joseph Jenkins, M.D.
                                                            Attorney-in-Fact1
- --------
     1            Pursuant to a Power of Attorney given by the Limited Partners.



                                                         2


<PAGE>



                                                                    SCHEDULE A-3

                        Schedule of Partnership Interests

              LOUISIANA LITHOTRIPSY INVESTMENT LIMITED PARTNERSHIP

            CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND INTERESTS

                                 Cash Contribution(1)     Percentage Interest(2)
                                  -----------------        -------------------
General Partner

Lithotripters, Inc.                  $1,000.00                   1.165%
2008 Litho Place, Suite 201
Fayetteville, NC  28304
Limited Partners

Thomas Alderson, M.D.                $2,000.00                   2.281%
234 S. Ryan
Lake Charles, LA  70601
David Autin, M.D.                    $2,500.00                   2.853%
4212 W. Congress
Lafayette, LA  70503
Bruce Bass, M.D.                     $1,000.00                   1.136%
234 S. Ryan
Lake Charles, LA  70601
Al Beachum, M.D.                     $3,500.00                   3.989%
913 S. College Road
Lafayette, LA  70503
Maged R. Botros, M.D.                $2,500.00                   2.853%
Mary Dickerson Hospital
Jasper, TX  75951
J. Bourdreau, M.D.                   $1,000.00                   1.136%
4212 W. Congress
Lafayette, LA  70503
Charles Bowie, M.D.                  $1,000.00                   0.757%
4400 Moosa Blvd.
Eunice, LA  70535
Edward Breaux, M.D.                  $2,000.00                   2.281%
118 Hospital Drive
Lafayette, LA  70503




                                                         1


<PAGE>



                          Cash Contribution(1)            Percentage Interest(2)
Joseph Busby, M.D.              $2,500.00                        2.853%
2104-G Loop Road
Winnsboro, LA  71295
J. Michael Cage, M.D.           $2,500.00                        1.902%
711 St. John Street
Monroe, LA  71201
Gerardo Chica, M.D.             $2,000.00                        2.281%
1323 S. 27th, Suite 300
Nederland, TX  77627
Martin Ducote, M.D.             $3,500.00                        3.989%
604 St. Landry Street
Lafayette, LA  70506
Edwin Edgerton, M.D.            $1,000.00                        0.757%
2417 N. 7th Street
West Monroe, LA  71291
John Enright, M.D.              $2,000.00                        2.281%
234 S. Ryan
Lake Charles, LA  70601
Christopher P. Fontenot(3)     $32,028.00                        1.180%
Carroll Guinn, M.D.             $1,000.00                        1.136%
602 N. Lewis
New Iberia, LA  70560
James M. Harris, M.D.           $2,000.00                        2.281%
810 Hospital Drive
Beaumont, TX  77701
John Denton Harris, M.D.        $3,500.00                        3.989%
810 Hospital Drive
Beaumont, TX  77701
G. Bruce Healey, M.D.           $2,000.00                        2.281%
3020 Allison
Groves, TX  77619
Gordon Sean Healey(3)          $16,014.00                        0.590%
John Henderson, M.D.            $2,500.00                        2.853%
810 Hospital Drive
Beaumont, TX  77701




                                                         2


<PAGE>



                                  Cash Contribution(1)    Percentage Interest(2)
George Hoffman, M.D.                 $2,500.00                   2.853%
3212 Concord Dr., Suite F
Orange, TX  77630
Brad Johnson(3)                     $32,028.00                   1.180%
Thomas Jordan                          $281.25                   0.425%
233 W. Broadway, Suite 501
Louisville, KY  40202
Chuen K. Kwok(3)                    $32,028.00                   1.180%
Edmond Lamperez, M.D.                $1,000.00                   0.757%
602 N. Lewis
New Iberia, LA  70560
Arthur Liles, M.D.                   $2,500.00                   2.853%
711 St. John Street
Monroe, LA  71201
Lithotripters, Inc.(4)               $2,000.00                   8.467%
2008 Litho Place
Fayetteville, NC  28304
Leo Lowentritt, M.D.                 $2,500.00                   2.853%
3311 Prescott Road
Alexandria, LA  71301
Don F. Marx, M.D.                    $2,500.00                   2.853%
North Monroe Medical Plaza
Suite I
Monroe, LA  71203

Robert Marx, M.D.                    $2,000.00                   2.281%
417 Wood Street
Monroe, LA  71201
James Meek, M.D.                     $2,000.00                   1.523%
301 4th Street
Alexandria, LA  71301
Charles E. Moss, M.D.                $2,000.00                   2.281%
118 Hospital Drive
Lafayette, LA  70503
Seth Novoselsky, M.D.                $1,000.00                   1.136%
3311 Prescott Road
Suite 103
Alexandria, LA  71301




                                                         3


<PAGE>



                            Cash Contribution(1)          Percentage Interest(2)
Tika Ranjitkar, M.D.            $2,000.00                             2.281%
1200 S. Farmerville
Ruston, LA  71270
James Rounder, M.D.             $1,000.00                             1.136%
3311 Prescott Road
Suite 103
Alexandria, LA  71301
Manuel Soasai, M.D.             $2,500.00                             2.853%
710 S. 8th Street
Beaumont, TX  77701
Steven A. Socher(3)             $32,028.00                            1.180%
Benjamin Stage, M.D.             $2,500.00                            2.853%
612 S. Washington
Bastrop, PA  71220
Charles Tanner, M.D.             $1,000.00                            0.757%
1200 S. Farmerville
Ruston, LA  71270
Lane Templeton(3)               $32,028.00                            1.180%
Paul Tennis, M.D.                $2,500.00                            2.853%
711 St. John Street
Monroe, LA  71201
Richard Texada, M.D.             $1,000.00                            1.136%
3311 Prescott Road
Alexandria, LA  71301
Jack Thielen, M.D.               $1,000.00                            1.136%
234 S. Ryan
Lake Charles, LA  70601
Kenneth S. Verheeck(3)          $32,028.00                            1.180%
J.W. Vildibill, M.D.             $3,500.00                            3.989%
604 St. Landry Street
Lafayette, LA  70506
         TOTAL                  286,463.25                           100.00%

(1)      The cash contributions  reflect the initial cash contributions of those
         Partners who currently hold an interest in the Partnership.

(2)      Percentage figures are approximated.



                                                         4


<PAGE>



(3)      Limited partnership interest was acquired pursuant to the Partnership's
         dilution offering which closed March 31, 1999.

(4) Lithotripters,  Inc. acquired a portion of its percentage interests pursuant
to various assignments from limited partners of the Partnership  effective as of
January 1,  1997,  and made no cash  contributions  to the  Partnership  for the
limited partner interests received as a result of such assignments.



                                                         5


<PAGE>



                        AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                    TEXAS I PROSTATHERAPY LIMITED PARTNERSHIP

THE  LIMITED  PARTNERSHIP  INTERESTS  REPRESENTED  BY THIS  LIMITED  PARTNERSHIP
AGREEMENT HAVE NOT BEEN REGISTERED  WITH THE SECURITIES AND EXCHANGE  COMMISSION
UNDER THE SECURITIES ACT OF 1933, AS AMENDED,  OR REGISTERED OR QUALIFIED  UNDER
ANY STATE  SECURITIES LAWS OR ACTS IN RELIANCE UPON EXEMPTIONS  UNDER SUCH LAWS.
IN ADDITION,  NO TRANSFERS OF LIMITED PARTNERSHIP  INTERESTS MAY BE MADE WITHOUT
COMPLIANCE WITH THE RESTRICTIONS SET FORTH IN ARTICLE 16 HEREIN.



<PAGE>



                                    AGREEMENT

                             OF LIMITED PARTNERSHIP

                                       OF

                    TEXAS I PROSTATHERAPY LIMITED PARTNERSHIP

                                TABLE OF CONTENTS


         1.       FORMATION..................................................1
                  ---------

         2.       NAME.......................................................1
                  ----

         3.       OFFICES....................................................1
                  -------

         4.       PURPOSE....................................................1
                  -------

         5.       TERM.......................................................2
                  ----

         6.       CERTAIN DEFINED TERMS......................................2
                  ---------------------

         7.       CAPITAL CONTRIBUTIONS AND DILUTION OFFERINGS...............6
                  --------------------------------------------

         8.       CONDITIONS TO THE CAPITAL CONTRIBUTIONS OF CERTAIN LIMITED
                  ----------------------------------------------------------
                  PARTNERS...................................................6
                  --------

         9.       REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE GENERAL
                  --------------------------------------------------------
                  PARTNER....................................................7
                  -------

         10.      ADMISSION OF LIMITED PARTNERS..............................8
                  -----------------------------

         11.      CAPITAL ACCOUNTS...........................................8
                  ----------------

         12.      ALLOCATIONS................................................9
                  -----------

         13.      DISTRIBUTIONS.............................................13
                  -------------

         l4.      RIGHTS AND OBLIGATIONS OF LIMITED PARTNERS................13
                  ------------------------------------------

         15.      LIMITED LIABILITY.........................................15
                  -----------------

         16.      TRANSFER OF INTERESTS AND ADMISSION OF PARTNERS...........16
                  -----------------------------------------------


                                                         i


<PAGE>




         17.      OPTIONAL PURCHASE OF LIMITED PARTNERSHIP INTERESTS ON
                  -----------------------------------------------------
                  CERTAIN EVENTS............................................20
                  --------------

         18.      SALE, ASSIGNMENT OR OTHER TRANSFER OF THE GENERAL PARTNER'S
                  -----------------------------------------------------------
                  INTEREST..................................................24
                  --------

         19.      TERMINATION OF THE SERVICES OF THE GENERAL PARTNER........25
                  --------------------------------------------------

         20.      MANAGEMENT AND OPERATION OF BUSINESS......................26
                  ------------------------------------

         21.      RESERVES..................................................29
                  --------

         22.      INDEMNIFICATION AND EXCULPATION OF THE GENERAL PARTNER
                  ------------------------------------------------------
                   .........................................................29

         23.      DISSOLUTION OF THE PARTNERSHIP............................29
                  ------------------------------

         24.      DISTRIBUTION UPON DISSOLUTION.............................31
                  -----------------------------

         25.      BOOKS OF ACCOUNT, RECORDS AND REPORTS.....................31
                  -------------------------------------

         26.      NOTICES...................................................32
                  -------

         27.      AMENDMENTS................................................33
                  ----------

         28.      LIMITATIONS ON AMENDMENTS.................................33
                  -------------------------

         29.      MEETINGS, CONSENTS AND VOTING.............................33
                  -----------------------------

         30.      SUBMISSIONS TO THE LIMITED PARTNERS.......................34
                  -----------------------------------

         31.      ADDITIONAL DOCUMENTS......................................34
                  --------------------

         32.      SURVIVAL OF RIGHTS........................................34
                  ------------------

         33.      INTERPRETATION AND GOVERNING LAW..........................34
                  --------------------------------

         34.      SEVERABILITY..............................................34
                  ------------

         35.      AGREEMENT IN COUNTERPARTS.................................35
                  -------------------------

         36.      THIRD PARTIES.............................................35
                  -------------


                                                        ii


<PAGE>




         37.      POWER OF ATTORNEY.........................................35
                  -----------------

         38.      ARBITRATION...............................................36
                  -----------

         39.      CREDITORS.................................................36
                  ---------


                                    SCHEDULES

Schedule A  -  Schedule of Partnership Interests


                                                        iii


<PAGE>




                                    AGREEMENT

                             OF LIMITED PARTNERSHIP

                                       OF

                    TEXAS I PROSTATHERAPY LIMITED PARTNERSHIP

                  THIS AGREEMENT OF LIMITED  PARTNERSHIP  (the  "Agreement")  is
made as of December 31,  1999,  by and among  PROSTATHERAPIES,  INC., a Delaware
corporation (the "General  Partner"),  and persons listed on Schedule A attached
hereto as the Limited Partners.

                  1.       FORMATION.
                           ---------

                  The  Partnership  was  formed  pursuant  to the  filing in the
Office  of the  Secretary  of State of Texas on or about  August  11,  1997 of a
Certificate of Limited Partnership in accordance with the provisions of the Act.

                  2.       NAME.
                           ----

     2.1  The  name  of  the  Partnership  is  "Texas  I  Prostatherapy  Limited
Partnership."

                  2.2 The  Partnership  business  shall be conducted  under such
names as the General  Partner may from time to time deem necessary or advisable,
provided that appropriate amendments to this Agreement and all necessary filings
under  applicable  assumed  or  fictitious  name  statutes  or the Act are first
obtained.

                  3.       OFFICES.
                           -------

                  3.1 The initial  principal office of the Partnership  shall be
at 1301 Capital of Texas Highway,  Suite C-300,  Austin, Texas 78746, or at such
other place as the General  Partner may, from time to time,  designate by notice
to the Limited Partners.

                  3.2 The Partnership  may have such  additional  offices as the
General Partner may, from time to time, deem necessary or advisable.

                  4.       PURPOSE.
                           -------

                  The purpose and business of the  Partnership  shall be: (i) to
acquire and operate one or more  Prostatron(R)  Mobile Systems for the treatment
of BPH  primarily  in the Service  Area or in other  location(s)  as the General
Partner may determine,  in its sole  discretion,  to be in the best interests of
the Partnership;  (ii) to acquire and operate in the future any other urological
device(s)  or  equipment,  provided  that  such  equipment  as of  the  date  of
acquisition by the  Partnership  has received FDA premarket  approval;  (iii) to
acquire an interest in any business entity, including,


                                                        -1-


<PAGE>



without  limitation,  a  limited  partnership,   limited  liability  company  or
corporation,  that engages in any business activity described in this Article 4;
and (iv) to  engage  in any and all  activities  incidental  or  related  to the
foregoing, upon and subject to the terms and conditions of this Agreement.

                  5.       TERM.
                           ----

                  The Partnership  shall terminate on December 31, 2047,  unless
sooner terminated as herein provided.

                  6.       CERTAIN DEFINED TERMS.
                           ---------------------

                  Certain terms used in this Agreement  shall have the following
meanings:

     Act. The Act means the Texas Revised  Limited  Partnership  Act, as then in
effect.

                  Affiliate.  An  Affiliate  is  (i)  any  person,  partnership,
corporation, association or other legal entity ("person") directly or indirectly
controlling, controlled by or under common control with another person; (ii) any
person owning or controlling 10% or more of the  outstanding  voting interest of
such other person;  (iii) any officer,  director or partner of such person;  and
(iv) if such other  person is an officer,  director  or partner,  any entity for
which such person acts in such capacity.

     Agreement.  This  Agreement  of  Limited  Partnership,  as the  same may be
amended from time to time.

                  BHP.  Benign prostatic hyperplasia.


     Capital Account.  The Partnership  capital account of a Partner as computed
pursuant to Article 11 of this Agreement.

                  Capital  Contributions.  All capital  contributions  made by a
Partner or his or her  predecessor  in  interest  which shall  include,  without
limitation, contributions made pursuant to Article 7 of this Agreement.

     Capital  Transaction.  Any transaction which, were it to generate proceeds,
would produce Partnership Sales Proceeds or Partnership Refinancing Proceeds.

     Code.  The Internal  Revenue  Code of 1986,  as amended,  or  corresponding
provisions of subsequent, superseding revenue laws.

                  Dilution  Offering.   As  provided  in  Article  7.4  of  this
Agreement,  the future offering of additional limited  partnership  interests in
the  Partnership  as  determined  by the General  Partner.  Except as  otherwise
provided in Article 7.4, any successful  Dilution Offering will  proportionately
reduce the Percentage Interests of the then current Partners in the Partnership.


                                                        -2-


<PAGE>



     Domestic Proceeding. Any divorce, annulment, separation or similar domestic
proceeding between a married couple.

                  Equipment.   The  equipment  used  in  the  operation  of  the
Prostatron(R)  Mobile System,  including the mobile coach, the Prostatron(R) and
miscellaneous  medical  equipment  and  supplies,  and  any  similar  additional
equipment acquired by the Partnership in the future.

                  FDA.  The United States Food and Drug Administration.


     General Partner.  The general partner of the Partnership,  Prostatherapies,
Inc., a Delaware corporation.

     Initial  Limited  Partner.  James Cochran,  M.D., a resident of Texas.  The
Initial  Limited  Partner is to be the only limited  partner of the  Partnership
until such time as the new Limited Partners are admitted to the Partnership,  at
which time the Initial Limited Partner shall withdraw from the Partnership.

                  Limited Partners.  The Limited Partners are those investors in
the Units  admitted  to the  Partnership  and any person  admitted  as a Limited
Partner in accordance with the provisions of this Agreement.

     Losses.  The net loss (including Net Losses from Capital  Transactions)  of
the  Partnership  for each Year of the  Partnership  as  determined  for federal
income tax purposes.

                  Majority  in Interest  of the  Limited  Partners.  The Limited
Partners who hold more than 50% of the Percentage  Interests in the  Partnership
held by the Limited Partners.

     Memorandum.   The  Confidential   Private   Placement   Memorandum  of  the
Partnership dated June 22, 1999, as amended or as supplemented.

                  Net Gains from Capital Transactions. The gains realized by the
Partnership  as a result of or upon any sale,  exchange,  condemnation  or other
disposition of the capital assets of the Partnership (which assets shall include
Code Section 1231 assets) or as a result of or upon the damage or destruction of
such capital assets.

                  Net Losses from Capital  Transactions.  The losses realized by
the Partnership as a result of or upon any sale, exchange, condemnation or other
disposition of the capital assets of the  Partnership  (which shall include Code
Section 1231 assets) or as a result of or upon the damage or destruction of such
capital assets.

     Offering.  The offer to potential  investors  of 320 Units  pursuant to the
Memorandum.




                                                        -3-


<PAGE>



     Partners. The General Partner and the Limited Partners, collectively, where
no distinction is required by the context in which the term is used herein.

     Partnership.  Texas I Prostatherapy  Limited  Partnership,  a Texas limited
partnership.

                  Partnership Cash Flow. For the applicable  period, the excess,
if any,  of (A) the sum of (i) all  gross  receipts  from  any  source  for such
period,  other than from  Partnership  loans,  Capital  Transactions and Capital
Contributions,  and (ii) any funds released by the  Partnership  from previously
established  reserves,  over  (B) the sum of (i) all cash  expenses  paid by the
Partnership  for such  period;  (ii) the amount of all  payments of principal on
loans to the Partnership;  (iii) capital  expenditures of the  Partnership;  and
(iv) such  reasonable  reserves as the General  Partner shall deem  necessary or
prudent to set aside for future repairs,  improvements or equipment  replacement
or additions,  or to meet working capital requirements or foreseen or unforeseen
future liabilities and contingencies of the Partnership; provided, however, that
the  amounts  referred  to in (B)(i),  (ii) and (iii)  above shall be taken into
account  only to the extent not funded by Capital  Contributions,  loans or paid
out of previously  established reserves.  Such term shall also include all other
funds deemed  available for  distribution  and designated as  "Partnership  Cash
Flow" by the General Partner.

     Partnership  Interest.  The  interest  of a Partner in the  Partnership  as
defined by the Act and this Agreement.

                  Partnership  Refinancing Proceeds.  The cash realized from the
refinancing of Partnership assets after retirement of any secured loans and less
(i) payment of all expenses  relating to the transaction and (ii)  establishment
of such  reasonable  reserves as the General  Partner  shall deem  necessary  or
prudent to set aside for future repairs,  improvements, or equipment replacement
or additions,  or to meet working capital requirements or foreseen or unforeseen
future liabilities or contingencies of the Partnership.

                  Partnership  Sales Proceeds.  The cash realized from the sale,
exchange,  casualty  or other  disposition  of all or a portion  of  Partnership
assets after the retirement of all secured loans and less (i) the payment of all
expenses  related to the transaction and (ii)  establishment  of such reasonable
reserves as the General Partner shall deem necessary or prudent to set aside for
future repairs,  improvements, or equipment replacement or additions, or to meet
working  capital  requirements or foreseen or unforeseen  future  liabilities or
contingencies of the Partnership.

                  Percentage  Interest.  The  interest  of each  Partner  in the
Partnership,  to be  determined  initially  in the case of a Limited  Partner by
reference to his or her Unit ownership based upon the Limited  Partners  holding
an aggregate 80% Percentage Interest in the Partnership,  with each initial Unit
sold representing an initial 0.25% interest.  The General Partner will initially
own a 20%  Percentage  Interest  in  the  Partnership.  A  Partner's  Percentage
Interest may be reduced by a future Dilution Offering.  The Partners' Percentage
Interests in the  Partnership as of the date hereof are as set forth in Schedule
A attached hereto. Any future adjustments in the Partners' Percentage Interests,
due to  future  Dilution  Offerings  or  otherwise,  will also be  reflected  by
amendments to Schedule A.


                                                        -4-


<PAGE>



                  Pro  Rata  Basis.   In   connection   with  an  allocation  or
distribution,  an allocation  or  distribution  in proportion to the  respective
Percentage Interests of the class of Partners to which reference is made.

     Profit. The net income of the Partnership (including Net Gains from Capital
Transactions)  for each Year of the Partnership as determined for federal income
tax purposes.

                  Prostatron(R).     The    Prostatron(R)    Praktis(R)    Model
transurethral  microwave  thermotherapy  device  for  treatment  of BPH which is
manufactured by EDAP Technomed, Inc.. The Prostratron(R) will be acquired by the
Partnership with the proceeds of this Offering and the General Partner's initial
cash contributions upon the successful closing of this Offering.

     Prostatron(R)Mobile  System.  The  mobile  coach  with  the  installed  and
operational Prostatron(R)and ultrasound system.

     Sales Agency  Agreement.  The sales agency agreement  through which MedTech
Investments,  Inc.,  an  Affiliate  of the General  Partner and a  broker-dealer
company  registered with the Securities and Exchange  commission and a member of
the National Association of Securities Dealers,  Inc. shall offer and sell up to
320 Units pursuant to the Memorandum.

     Sales  Commission.  The $75 sales  commission paid to MedTech  Investments,
Inc. for each Unit sold.

                  Service.  The Internal Revenue Service.


                  Service  Area.  The  geographic  region  in which  Partnership
operations  are expected to be conducted and which is  anticipated to consist of
various  regions in the State of Texas.  The General Partner has sole discretion
to expand the service area.

                  TUMT.  Transurethral microwave thermotherapy.


     Units. The 320 equal limited partner  interests in the Partnership  offered
pursuant to the Memorandum for a price per Unit of $1,875 in cash.

     Year. An annual accounting period ending on December 31 of each year during
the term of the Partnership.

                  7.       CAPITAL CONTRIBUTIONS AND DILUTION OFFERINGS.
                           --------------------------------------------

                  7.1  General  Partner  Contribution.  On or before the date of
this  Agreement,  the  General  Partner  will  contribute  to the capital of the
Partnership  cash in the amount  equal to 20% (up to $150,000) of the total cash
contributed to the  Partnership by the Partners in the Offering made pursuant to
the Memorandum.


                                                        -5-


<PAGE>



                  7.2 Limited Partner Contribution.  Each Limited Partner hereby
agrees to contribute and shall  contribute to the capital of the  Partnership on
the date of his or her  admission to the  Partnership  the cash amount set forth
opposite his or her name on Schedule A attached hereto.

     7.3 No Interest.  Except as otherwise provided herein, no interest shall be
paid on any contribution to the capital of the Partnership.

                  7.4 Dilution  Offerings.  If the General Partner,  in its sole
discretion,  determines that it is in the best interest of the Partnership,  the
General Partner may, from time to time, offer, sell and issue, for and on behalf
of the Partnership,  additional limited partnership interests in the Partnership
(a  "Dilution  Offering")  to  investors  who are not already  Limited  Partners
("Qualified  Investors").  The primary purpose of any Dilution Offering would be
to raise additional capital for any legitimate  Partnership purpose as set forth
in Article 4. Any limited partnership  interests offered by the Partnership in a
Dilution  Offering  shall  be sold in the  manner  and  according  to the  terms
prescribed in the sole  discretion of the General  Partner;  provided,  however,
that any additional limited partnership interests offered in a Dilution Offering
will be sold for a price no lower than the highest price for which proportionate
limited  partnership  interests in the Partnership  have been previously sold by
the Partnership unless otherwise determined by a vote of the General Partner and
a Majority in Interest of the Limited  Partners.  Notwithstanding  the above, in
the event of a Dilution  Offering,  the General  Partner may elect,  in its sole
discretion,   to  prevent   dilution  of  its  Percentage   Interest  by  either
contributing  additional  capital to the  Partnership  or purchasing  additional
limited partnership  interests in any Dilution Offering.  Limited Partners shall
have no right to purchase  additional  limited partner interests in any Dilution
Offering or to make additional capital contributions or take any other action to
prevent dilution of their Percentage  Interest.  Any sale of additional  limited
partnership  interests  will  result  in  the  proportionate   dilution  of  the
Percentage Interests of the existing Partners.  Any investor acquiring a limited
partnership interest in a Dilution Offering shall agree to be bound by the terms
of this Agreement,  and shall be automatically  admitted as a Limited Partner of
the Partnership.  Any adjustment in the Partners' Percentage Interests resulting
from a  Dilution  Offering  shall be set forth on an  amended  Schedule  A to be
attached hereto.

                  8.       CONDITIONS TO THE CAPITAL CONTRIBUTIONS OF CERTAIN
                           --------------------------------------------------
                           LIMITED PARTNERS.
                           ----------------

                  The  obligations  of  any  Limited  Partners  acquiring  their
Partnership  Interests  in the  Offering  or a  Dilution  Offering  to make cash
Capital   Contributions   hereunder  are  subject  to  the  condition  that  the
representations, warranties, agreements and covenants of the General Partner set
forth in Article 9 of this  Agreement  are and shall be true and correct or have
been and will have been complied with in all material  respects on the date such
Capital  Contributions  are  required to be made,  except to the extent that any
such representation or warranty expressly pertains to an earlier date.


                                                        -6-


<PAGE>



                  9.       REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE
                           ------------------------------------------------
                           GENERAL PARTNER.
                           ---------------

     9.1 The  General  Partner  hereby  represents  and  warrants to the Limited
Partners that:

     (a) The Partnership is a limited  partnership formed in accordance with and
validly  existing  under the Act and the other  applicable  laws of the State of
Texas;

                           (b) The interests in the  Partnership  of the Limited
         Partners will have been duly  authorized or created and validly  issued
         and the Limited Partners shall have no personal liability to contribute
         money  to  the  Partnership   other  than  the  amounts  agreed  to  be
         contributed  by them in the  manner  and on the terms set forth in this
         Agreement,  subject,  however,  to such  limitations  as may be imposed
         under the Act;

                           (c)  Except  as  disclosed  in  the   Memorandum   or
         documentation  prepared  in  connection  with a Dilution  Offering,  no
         material breach or default adverse to the Partnership  exists under the
         terms of any other material agreement affecting the Partnership; and

               (d) The  General  Partner  is a Delaware  corporation  formed and
          existing under the laws of the State of Delaware.

          9.2 The General Partner hereby covenants to the Limited Partners that:

          (a) It will at all times act in a fiduciary manner with respect to the
          Partnership and the Limited Partners;

          (b) Except as  provided  in Article  18, it will serve as the  General
          Partner of the Partnership until the Partnership is terminated without
          reconstitution; and

                           (c) It will cause the  Partnership  to carry adequate
         public  liability,  property damage and other insurance as is customary
         in the business to be engaged in by the Partnership.

                  10.      ADMISSION OF LIMITED PARTNERS.
                           -----------------------------

                  The  General  Partner may permit the offer and sale of limited
partnership  interests on the terms and conditions provided in the Memorandum or
future Dilution Offerings and may admit



                                                        -7-


<PAGE>



persons  subscribing for interests as Limited Partners in the Partnership on the
terms and conditions set forth in this Article 10.

                           (a) The General  Partner  shall have  approved of the
         admission of said person in writing on such terms and conditions as the
         General Partner shall determine;

                           (b) Said person shall have executed such documents or
         instruments  as the General  Partner may deem necessary or desirable to
         effect his or her admission as a Limited Partner;

               (c)  Said person shall have accepted and adopted all of the terms
                    and provisions of this Agreement, as then amended;

                           (d) Said person (if a  corporation)  shall deliver to
         the General  Partner a certified  copy of a resolution  of its Board of
         Directors  authorizing  it to become a Limited  Partner under the terms
         and conditions of this Agreement; and

                           (e) Said person, upon request by the General Partner,
         shall pay such  reasonable  expenses as may be  incurred in  connection
         with its admission as a Limited Partner.

                  11.      CAPITAL ACCOUNTS.
                           ----------------

                  A Capital  Account shall be  established  for each Partner and
shall at all times be determined  and  maintained  in accordance  with the Final
Treasury  Regulations  under  Section  704(b)  of the  Code,  as the same may be
amended.  A Partner  shall not be entitled  to  withdraw  any part of his or her
Capital Account or to receive any distribution  from the Partnership,  except as
provided in Articles 13 and 24.

               (a) Each Partners' Capital Account shall be increased by:

               (i) The amount of his or her  Capital  Contribution  pursuant  to
          Article 7; and

               (ii) The amount of Profits  allocated  to him or her  pursuant to
          Article 12; and

                                    (iii)   The   Partner's   pro   rata   share
                  (determined  in the same  manner  as such  Partner's  share of
                  Profits and Losses allocated pursuant to Article 12 hereof) of
                  any income or gain exempt from tax.

               (b) Each Partner's Capital Account shall be decreased by:



                                                        -8-


<PAGE>




               (i) The  amount of Losses  allocated  to him or her  pursuant  to
          Article 12; and

                                    (ii) The  amount of  Partnership  Cash Flow,
                  Partnership   Sales  Proceeds  and   Partnership   Refinancing
                  Proceeds distributed to him or her pursuant to Article 13; and

                                    (iii) The  Partner's  pro rata  share of any
                  other expenditures of the Partnership which are not deductible
                  in computing  Partnership  Profits or Losses and which are not
                  added to the tax basis of any Partnership property, including,
                  without   limitation,   expenditures   described   in  Section
                  705(a)(2)(B) of the Code. The Partner's pro rata share of such
                  expenditures  shall be  determined  in the same manner as such
                  Partner's  share of Profits and Losses  allocated  pursuant to
                  Article 12.

                  12.      ALLOCATIONS

               (a)  Nonrecourse  Deductions.  Nonrecourse  Deductions  shall  be
          allocated  among the  Partners  in  accordance  with their  respective
          Percentage Interests.

                           (b)  Partner  Nonrecourse  Deductions.   Any  Partner
         Nonrecourse  Deductions shall be specially allocated to the Partner who
         bears the economic risk of loss with respect to the Partner Nonrecourse
         Debt to which such Partner  Nonrecourse  Deductions are attributable in
         accordance with Treasury Regulations Section 1.704-2(i).

                           (c)      Profits and Losses.

                                    (i)   The   Profits   and   Losses   of  the
                  Partnership   shall  be   allocated   among  the  Partners  in
                  accordance  with their  respective  Percentage  Interests.  In
                  allocating  Profits  and  Losses,  Net Gains and  Losses  from
                  Capital  Transactions (a part of Profits and Losses),  if any,
                  shall be allocated first.

                                    (ii) In no event shall  Losses be  allocated
                  under this  Article  12(c) to a Limited  Partner if and to the
                  extent that such allocation  would cause, as of the end of the
                  Year, the negative balance in such Limited  Partner's  Capital
                  Account to exceed such Limited  Partner's share of Partnership
                  Minimum Gain plus such  Limited  Partner's  share,  if any, of
                  Partner  Minimum  Gain.  Any Losses which are not allocated to
                  the Limited Partner by virtue of the


                                                        -9-


<PAGE>



                  application  of the preceding  sentence  shall be allocated to
                  the General  Partner.  For purposes of this Article  12(c),  a
                  Partner's  Capital  Account  shall be  treated  as  reduced by
                  Qualified   Income   Offset   Items  as  provided  in  Article
                  12(d)(iii).  All items of income,  gain, loss,  deduction,  or
                  credit shall be allocated among the Partners  proportionately.
                  Further, notwithstanding the foregoing, after giving effect to
                  the special  allocations in Article 12(d), the General Partner
                  shall be allocated  at least 1% of all items of income,  gain,
                  loss, deduction or credit.

               (d) Special Allocations.  The following special allocations shall
          be made:

                                    (i) Partnership Minimum Gain Chargeback.  If
                  there is a net decrease in Partnership Minimum Gain during any
                  Year,  each  Partner  shall be  specially  allocated  items of
                  Partnership  income and gain for such Year (and, if necessary,
                  subsequent  Years) in an amount equal to such Partner's  share
                  of the net decrease in Partnership Minimum Gain, determined in
                  accordance with Treasury  Regulations  Section  1.704-2(g)(2).
                  Allocations pursuant to the previous sentence shall be made in
                  proportion to the respective  amounts required to be allocated
                  to  each  Partner.  The  items  to be so  allocated  shall  be
                  determined in accordance  with  Treasury  Regulations  Section
                  1.704-2(f).  This Article  12(d)(i) is intended to comply with
                  the minimum gain chargeback requirement in such Section of the
                  Regulations and shall be interpreted consistently therewith.

                                    (ii)  Partner   Minimum   Gain   Chargeback.
                  Notwithstanding  any other provision of this Article 12 except
                  Article  12(d)(i),  if  there  is a net  decrease  in  Partner
                  Minimum Gain attributable to a Partner Nonrecourse Debt during
                  any Year,  each Partner who has a share of the Partner Minimum
                  Gain attributable to such Partner Nonrecourse Debt, determined
                  in accordance with Treasury  Regulations  Section  1.704-2(f),
                  shall be specially  allocated items of Partnership  income and
                  gain for such Year (and, if necessary, subsequent Years) in an
                  amount  equal to such  Partner's  share of the net decrease in
                  Partner Minimum Gain attributable to such Partner  Nonrecourse
                  Debt, to the extent  required by and  determined in accordance
                  with Treasury Regulations Section 1.704- 2(i)(4).  Allocations
                  pursuant to the previous  sentence shall be made in proportion
                  to the  respective  amounts  required to be  allocated to each
                  Partner pursuant  thereto.  The items to be so allocated shall
                  be


                                                       -10-


<PAGE>



                  determined in accordance  with  Treasury  Regulations  Section
                  1.704- 2(i)(4).  This Article  12(d)(ii) is intended to comply
                  with the minimum gain  chargeback  requirement in such Section
                  of the  Regulations  and  shall  be  interpreted  consistently
                  therewith.

                                    (iii)  Qualified   Income  Offset.   If  any
                  Partner  unexpectedly  receives any adjustment,  allocation or
                  distribution   described  in  Treasury   Regulations   Section
                  1.704-1(b)(2)(ii)(d)(4)  through (6) which causes or increases
                  a deficit balance in such Partner's  Capital Account (adjusted
                  for  this   purpose  in  the  manner   provided   in  Treasury
                  Regulations    Section    1.704-1(b)(2)(ii)(d)),    items   of
                  Partnership  income and gain shall be  specially  allocated to
                  each  such  Partner  in an amount  and  manner  sufficient  to
                  eliminate,  to the extent  required  by the  Regulations,  the
                  deficit   Capital  Account  of  such  Partner  as  quickly  as
                  possible, provided that an allocation pursuant to this Article
                  12(d)(iii)  shall be made if and only to the extent  that such
                  Partner would have a deficit  Capital  Account after all other
                  allocations   provided  for  in  this  Article  12  have  been
                  tentatively made as if this Article 12(d)(iii) were not in the
                  Agreement.  This  provision  is  intended  to be a  "qualified
                  income  offset,"  as defined in Treasury  Regulations  Section
                  1.704-1(b)(2)(ii)(d),   such  Regulation  being   specifically
                  incorporated herein by reference.

                                    (iv) Sales Commission.  The Sales Commission
                  shall be  allocated  to the  Units  which  are not held by the
                  General  Partner and its  Affiliates  and are  acquired in the
                  Offering in proportion to the respective capital contributions
                  represented by such Units (i.e., $75 in Sales  Commissions per
                  each such Unit).  The purpose of this Article  12(d)(iv) is to
                  allocate the Sales  Commission to those  Partners who actually
                  bore the burden of paying the Sales Commission.

               (e) Ordering Provision. In applying the provisions of Articles 12
          and 13 with respect to distributions  and  allocations,  the following
          ordering of priorities shall apply:

               (i) Capital  Accounts  shall be deemed to be reduced by Qualified
          Income Offset Items.

                                    (ii)  Capital  Accounts  shall be reduced by
                  Distributions of Partnership Cash Flow under Article 13(a).

                                    (iii)   Capital Accounts shall be reduced by


                                                       -11-


<PAGE>



                  Distributions of Partnership Sales Proceeds and Partnership
                  Refinancing Proceeds under Article 13(b).

                                    (iv) Capital  Accounts shall be increased by
                  any Minimum Gain Chargeback under Articles 12(d)(i) and (ii).

               (v) Capital  Accounts shall be increased by any Qualified  Income
          Offset under Article 12(d)(iii).

                                    (vi)  Capital  Accounts  shall be reduced by
                  allocations of Nonrecourse Deductions under Article 12(a).

                                    (vii) Capital  Accounts  shall be reduced by
                  allocations of Partner  Nonrecourse  Deductions  under Article
                  12(b).

                                    (viii)  Capital  Accounts shall be increased
                  by allocations of Profits under Article 12(c).

                                    (ix)  Capital  Accounts  shall be reduced by
                  allocations of Losses under Article 12(c).

                           To the  maximum  extent  permitted  under  the  Code,
         allocations  of  Profits  and  Losses  shall  be  modified  so that the
         Partners' Capital Accounts reflect the amount they would have reflected
         if adjustments  required by Articles  12(d)(i),  (ii) and (iii) had not
         occurred.

                           (f) Allocations Between Transferor and Transferee. In
         the  event of the  transfer  (other  than the  pledges  of the  General
         Partner's  interest  permitted  by  Article  18  or  Permitted  Pledges
         described  in  Article  16.2(b))  of  all or any  part  of a  Partner's
         interest (in accordance  with the provisions of this  Agreement) in the
         Partnership  at any  time  other  than  at the  end of a  Year,  or the
         admission  of a new  Partner  (in  accordance  with  the  terms of this
         Agreement),  the  transferring  Partner or new  Partner's  share of the
         Partnership's  income, gain, loss,  deductions and credits, as computed
         both for accounting purposes and for federal income tax purposes, shall
         be allocated between the transferor  Partner and the transferee Partner
         (or Partners),  or the new Partner and the other Partners,  as the case
         may be, in the same ratio as the number of days in such Year before and
         after the date of the transfer or admission; provided, however, that if
         there  has  been a sale  or  other  disposition  of the  assets  of the
         Partnership  (or any part thereof)  during such Year,  then the General
         Partner may elect, in its sole discretion,  to treat the periods before
         and after the date of the transfer or  admission as separate  Years and
         allocate the Partnership's net income,  gain, net loss,  deductions and
         credits for each of such deemed  separate  Years.  Notwithstanding  the
         foregoing, the Partnership's "allocable cash basis items," as that term
         is used in


                                                       -12-


<PAGE>



         Section  706(d)(2)(B)  of the Code,  shall be  allocated as required by
         Section 706(d)(2) of the Code and the regulations thereunder.

                           (g)  Tax  Withholding.   The  Partnership   shall  be
         authorized  to pay,  on  behalf  of any  Partner,  any  amounts  to any
         federal,  state or local taxing authority,  as may be necessary for the
         Partnership  to comply with tax  withholding  provisions of the Code or
         the other  income tax or revenue laws of any taxing  authority.  To the
         extent the Partnership pays any such amounts that it may be required to
         pay on behalf of a  Partner,  such  amounts  shall be treated as a cash
         distribution  to such  Partner  and shall  reduce the amount  otherwise
         distributable to such Partner.

                  13.      DISTRIBUTIONS.
                           -------------

                           (a)    Distribution   of   Partnership   Cash   Flow.
         Partnership  Cash Flow shall be distributed  to the Partners  within 60
         days after the end of each Year,  or earlier in the  discretion  of the
         General Partner, in proportion to their respective Percentage Interests
         at the time of distribution.

                           (b) Distribution of Partnership  Refinancing Proceeds
         and Partnership Sales Proceeds.  Partnership  Refinancing  Proceeds and
         Partnership  Sales Proceeds shall be distributed to the Partners within
         60 days of the Capital  Transaction  giving rise to such  proceeds,  or
         earlier in the  discretion  of the General  Partner,  in  proportion to
         their respective Percentage Interests at the time of distribution.

                           (c) Distribution in Liquidation.  Upon liquidation of
         the Partnership,  all of the  Partnership's  property shall be sold and
         Profits and Losses allocated accordingly. Proceeds from the liquidation
         of the Partnership shall be distributed in accordance with Article 24.

                  l4.      RIGHTS AND OBLIGATIONS OF LIMITED PARTNERS.
                           ------------------------------------------

                  14.1  Management.  The Limited Partners shall not take part in
the management of the business,  nor transact any business for the  Partnership,
nor  shall  they  have  power  to  sign  for or to  bind  the  Partnership.  The
Partnership may,  however,  contract with one or more Limited Partners to act as
the local medical  director(s) of the  Prostatron(R)  Mobile System.  No Limited
Partner may withdraw from the Partnership except as expressly permitted herein.

                  14.2 Operation of  Prostatron(R)  Mobile  System.  The Limited
Partners  shall not  operate or utilize  the  Partnership  Prostatron(R)  Mobile
System or other  Partnership  equipment except pursuant to (i) an agreement with
the  Partnership;  or (ii) any other  arrangement  specifically  approved by the
General Partner.


                                                       -13-


<PAGE>



                  14.3 Outside Activities.  The Limited Partners agree that they
owe fiduciary  duties to the  Partnership  and, as a  consequence,  each Limited
Partner (that is not the General Partner or an Affiliate of the General Partner)
agrees that (s)he shall not engage in "Outside Activities" (as defined below) in
the "Market  Area" (as defined  below)  while (s)he is a Limited  Partner in the
Partnership  and shall  otherwise be subject to the  provisions  of this Article
14.3.  The phrase  "Outside  Activities"  means  directly or indirectly  owning,
leasing or  subleasing  a TUMT device (or any  similar  equipment  or  competing
devices used for treating BPH) or any other  therapeutic  equipment  acquired by
the Partnership;  provided that an ownership  interest in the General Partner or
an Affiliate of the General  Partner shall not  constitute an Outside  Activity.
Prohibited  indirect  ownership shall include  without  limitation the direct or
indirect  ownership  of  any  interest  in a  business  venture  (through  stock
ownership,  partnership  interest  ownership,  ownership  by or  through a close
family member, or as otherwise  determined in good faith by the General Partner)
involving the ownership,  purchase,  lease, sublease,  promotion,  management or
operation of a TUMT device (or similar  equipment or competing  devices used for
treating BPH) or other competing device or equipment, unless the General Partner
determines that such activity by the Limited  Partners is not detrimental to the
best interests of the Partnership. Notwithstanding the above, Outside Activities
shall not include (i) ownership of less than 1% of the capital stock (calculated
on a fully  diluted  basis) of a  corporation  whose stock is publicly  owned or
regularly  traded on any public  exchange,  (ii) any  ownership  interest  in an
entity  engaging  in an  Outside  Activity  acquired  before  the  date  hereof;
provided,  that  the  Limited  Partner  may not  increase  or  enhance  any such
previously held  investment  during the term of the  Partnership,  and (iii) any
other activity determined by the General Partner, in its sole discretion, not to
be detrimental to the best interests of the Partnership.

                  Upon  the  termination  or  transfer  of a  Limited  Partner's
interest in the  Partnership  for any reason,  including a transfer  pursuant to
Article 17.3 hereof, the withdrawing  Limited Partner shall not, for a period of
two (2) years following the date of withdrawal, engage in any Outside Activities
in any "Market Area" in which the Partnership is transacting  business or within
the prior twelve months has transacted  business (the "Restricted  Facilities").
For the purposes of this Article 14.3, the term "Market Area" shall mean (i) the
area within a fifty (50) mile  radius of any  Restricted  Facility,  but if such
area is determined by a court of competent jurisdiction to be too broad, then it
shall  mean (ii) the area  within a thirty  (30) mile  radius of any  Restricted
Facility, but if such area is determined by a court of competent jurisdiction to
be too broad then it shall mean (iii) the area within a fifteen (15) mile radius
of any Restricted Facility.

                  In the event a Limited Partner wishes and intends to engage in
an Outside  Activity in a Market Area, he or she must provide  written notice of
such intent to the General  Partner  prior to engaging in the Outside  Activity.
The  written  notice  shall be deemed an  election  by the  Limited  Partner  to
withdraw from the Partnership (the "Notice of  Withdrawal"),  and shall give the
General  Partner the purchase  rights as provided in Article 17.3 hereof.  After
the Notice of Withdrawal,  the former  Limited  Partner may engage in an Outside
Activity in the Market Area only after waiting the period of two years specified
in this  Article  14.3.  In the  event of  breach  of the  waiting  period,  the
Partnership  shall be entitled  to any remedy at law or equity  with  respect to
such breach, including without limitation an injunction or suit for damages.


                                                       -14-


<PAGE>



                  If a Limited  Partner during his or her  participation  in the
Partnership  engages in an  Outside  Activity  in a Market  Area  without  first
notifying  the General  Partner in violation of this Article  14.3,  the Limited
Partner  shall be deemed to have  given a Notice of  Withdrawal  on the date the
General Partner first becomes aware of the Limited Partner's Outside Activity in
the Market Area.  Upon  receiving a Limited  Partner's  Notice of  Withdrawal or
equivalent  thereof,  the Partnership may invoke the purchase rights provided in
Article  17.3  and  shall be  entitled  to any  other  remedy  at law or  equity
including without limitation an injunction or suit for damages.

                  14.4  Disclosure  of  Confidential  Information.  Each Limited
Partner acknowledges and agrees that his or her participation in the Partnership
under this Agreement necessarily involves his or her understanding of and access
to certain trade secrets and other  confidential  information  pertaining to the
business of the Partnership.  Accordingly,  each Limited Partner (other than the
General   Partner  and  its  Affiliates  that  may  also  hold  Limited  Partner
Partnership  Interests) agrees that at all times during his or her participation
in the Partnership as a Limited Partner and thereafter, (s)he will not, directly
or indirectly, without the express written authority of the Partnership,  unless
required by law or directed by a applicable legal authority having  jurisdiction
over  the  Limited  Partner,  disclose  or use for the  benefit  of any  person,
corporation  or other  entity  (other  than  the  Partnership),  or the  Limited
Partner, (i) any trade, technical, operational, management or other secrets, any
patient or customer  lists or other  confidential  or secret data,  or any other
proprietary,  confidential or secret  information of the Partnership or (ii) any
confidential information concerning any of the financial arrangements, financial
condition,  hospital or  physician  contracts,  third party payor  arrangements,
quality assurance and outcome analysis programs, competitive status, customer or
supplier matters, internal organizational matters, technical abilities, or other
business affairs of or relating to the Partnership.  The Limited Partners (other
than the General  Partner and its Affiliates  that may also hold Limited Partner
Partnership  Interests)  acknowledge  that  all  of  the  foregoing  constitutes
proprietary information,  which is the exclusive property of the Partnership. In
the event of breach of this Article 14.4 as determined  by the General  Partner,
the Partnership shall be entitled to any remedy at law or equity with respect to
such breach, including without limitation, an injunction or suit for damages.

                  15.      LIMITED LIABILITY.
                           -----------------

                  No Limited Partner shall be required to make any  contribution
to the  capital of the  Partnership  except as set forth in Article 7, nor shall
any Limited  Partner in his or her capacity as such,  be bound by, or personally
liable for, any expense,  liability or obligation of the  Partnership  except to
the extent of his or her (i) interest in the  Partnership and (ii) obligation to
return distributions made to him or her under certain  circumstances as required
by the Act.


                                                       -15-


<PAGE>



                  16.      TRANSFER OF INTERESTS AND ADMISSION OF PARTNERS.
                           -----------------------------------------------

                  16.1     Transferability.
                           ---------------

                           (a) The term  "transfer"  when used in this Agreement
         with respect to a  Partnership  Interest  includes a sale,  assignment,
         gift,  pledge,  exchange or any other disposition (but does not include
         the  issuance  of new  Partnership  Interests  pursuant  to a  Dilution
         Offering);

               (b) Except as  otherwise  provided  herein,  the General  Partner
          shall not at any time transfer or assign its interest or obligation as
          General Partner;

                           (c) The  Partnership  Interest of any Limited Partner
         shall not be  transferred,  in whole or in part,  except in  accordance
         with the conditions and limitations set forth in Articles 16.2 or 17;

                           (d)  The  transferee  of a  Partnership  Interest  by
         assignment,  operation of law or otherwise, shall have only the rights,
         powers and privileges  enumerated in Article 16.3 or otherwise provided
         by law and may not be admitted to the  Partnership as a Limited Partner
         except as provided in Article  16.4 or as a General  Partner  except as
         provided in Article 16.5;

                           (e)  Notwithstanding  any  provision  herein  to  the
         contrary,  the  Partnership  Agreement  shall  in no way  restrict  the
         issuance or transfers of stock of the General  Partner or the merger of
         the General Partner with another person or entity; and

                           (f)  Notwithstanding  any  provision  herein  to  the
         contrary,  the issuance of Partnership Interests pursuant to a Dilution
         Offering  and the  admission  of new  Limited  Partners  pursuant  to a
         Dilution Offering shall be governed by the provisions of Article 7.4 of
         this Agreement.

                  16.2     Restrictions on Transfers by Limited Partners.
                           ---------------------------------------------

                           (a)  All or  part of a  Partnership  Interest  may be
         transferred by a Limited  Partner only with the prior written  approval
         of the General Partner,  which approval may be granted or denied in the
         sole discretion of the General Partner.

                           (b)  The  General   Partner  shall  not  approve  any
         transfer of a Partnership Interest,  except a pledge of any Partnership
         Interest by the General Partner to any bank, insurance company or other
         financial  institution to secure payment of  indebtedness (a "Permitted
         Pledge"),  or  otherwise  unless  the  proposed  transferee  shall have
         furnished the General Partner with a sworn statement that:


                                                       -16-


<PAGE>



               (i)  The  proposed  transferee  proposes  to  acquire  his or her
          Partnership  Interest as a principal,  for  investment  and not with a
          view to resale or distribution;

                                    (ii)  The  proposed  transferee  meets  such
                  requirements regarding sophistication, income and net worth as
                  required by applicable state and federal securities laws;

                                    (iii) The proposed  transferee  has met such
                  net  worth  and  income  suitability  standards  as have  been
                  established by the General Partner;

                                    (iv) The proposed transferee recognizes that
                  investment in the Partnership  involves  certain risks and has
                  taken  full  cognizance  of and  understands  all of the  risk
                  factors related to the purchase of a Partnership Interest; and

               (v) The proposed transferee has met all other requirements of the
          General Partner for the proposed transfer.

                           (c) Other than in the case of a Permitted  Pledge,  a
         transfer of a  Partnership  Interest  may be made only if, prior to the
         date  thereof,  the  Partnership  upon  request  receives an opinion of
         counsel,  satisfactory  in form and  substance to the General  Partner,
         that  neither the  offering  nor the  proposed  transfer  will  require
         registration  under  federal or  applicable  state  securities  laws or
         regulations.

                  16.3 Rights of Transferee.  Unless admitted to the Partnership
in accordance  with Article 16.4, the transferee of a Partnership  Interest or a
part thereof or any right,  title or interest  therein  shall not be entitled to
any of the rights,  powers, or privileges of his or her predecessor in interest,
except that (s)he  shall be entitled to receive and be credited or debited  with
his or her proportionate share of Partnership income,  gains,  Profits,  Losses,
deductions, credits or distributions.

                  16.4  Admission  of  Limited  Partners.  Except  as  otherwise
provided in Article 17, the General Partner, or the transferee of all or part of
the Partnership  Interest of either a General Partner or a Limited Partner,  may
be admitted to the  Partnership  as a Limited  Partner  upon  furnishing  to the
General Partner all of the following:

                           (a) The written approval of a Majority in Interest of
         all of the Limited  Partners  (except  the  assignor  Partner),  or the
         assignor Partner alone,  which approval may be granted or denied in the
         sole discretion of such Partners or Partner (as the case may be);


                                                       -17-


<PAGE>



               (b) The written approval of the General  Partner,  which approval
          may be  granted  or  denied  in the  sole  discretion  of the  General
          Partner;

                           (c) Acceptance, in a form satisfactory to the General
         Partner,  of all the terms and  conditions  of this  Agreement  and any
         other  documents  required  in  connection  with the  operation  of the
         Partnership pursuant to the terms of this Agreement;

               (d) A properly executed power of attorney substantially identical
          to that contained in Article 37;

               (e) Such other  documents  or  instruments  as may be required in
          order to effect his or her admission as a Limited Partner; and

               (f)  Payment of such  reasonable  expenses  as may be incurred in
          connection with his or her admission as a Limited Partner.

               16.5 Admission of General  Partners.  A Limited  Partner,  or the
          transferee of all or part of the  Partnership  Interest of the General
          Partner,  may be admitted to the Partnership as a general partner upon
          furnishing to the General Partner all of the following:

                           (a) The written  consent of both the General  Partner
         and a Majority in Interest of the Limited  Partners,  which consent may
         be granted or denied in the sole discretion of the Partners;

                           (b) Such  financial  statements,  guarantees or other
         assurances  as the  General  Partner  may  require  with  regard to the
         ability  of the  proposed  general  partner to  fulfill  the  financial
         obligations of a general partner hereunder;

                           (c) Acceptance,  in form  satisfactory to the General
         Partner,  of all the terms and  provisions  of this  Agreement  and any
         other  documents  required  in  connection  with the  operation  of the
         Partnership pursuant to the terms of this Agreement;

               (d) A certified  copy of a  resolution  of its Board of Directors
          (if it is a corporation)  authorizing  it to become a general  partner
          under the terms and conditions of this Agreement;

               (e) A power of attorney substantially identical to that contained
          in Article 37;

               (f) Such other  documents  or  instruments  as may be required in
          order to effect his, her or its admission as a general partner; and


                                                       -18-


<PAGE>



               (g)  Payment of such  reasonable  expenses  as may be incurred in
          connection with his, her or its admission as a general partner.

                  Notwithstanding  the above,  a transferee  that controls or is
controlled by the General Partner or one or more of its Affiliates that receives
all or part of the  Partnership  Interest of the General Partner may be admitted
to the  Partnership as a general  partner upon complying with all the provisions
of Article  16.5  except for  subparagraph  16.5(a).  As long as the  transferee
either  controls or is controlled  by the General  Partner or one or more of its
Affiliates,  no  Limited  Partner  consents  will  be  required  to  admit  such
transferee as a general partner to the Partnership.

                  16.6  Amendment  of  Certificate  of Limited  Partnership  and
Qualification.   The  General   Partner  shall  take  all  steps  necessary  and
appropriate to prepare and record any  amendments to the  Certificate of Limited
Partnership, as may be necessary or appropriate from time to time to comply with
the requirements of the Act, including,  without limitation,  upon the admission
to the Partnership of any general partner  pursuant to the provisions of Article
16.5, and may for this purpose  exercise the power of attorney  delivered to the
General Partner pursuant to Article 16.5 or 37. In addition, the General Partner
shall take all steps necessary and appropriate to prepare and record any and all
documents  necessary to qualify the Partnership to do business in  jurisdictions
where the Partnership is doing business,  and may for this purpose  exercise the
power of attorney  delivered to the General  Partner  pursuant to Articles 16.4,
16.5 or 37.

                  16.7 Fundamental  Changes.  In the event a plan is approved by
the General Partner and a Majority in Interest of the Limited Partners providing
for the  merger or  consolidation  of the  Partnership  with  another  person or
entity,  or the sale of all or substantially  all of the Partnership  Interests,
including  without  limitation the exchange of Partnership  Interests for equity
interests  in  another  person or entity or for cash or other  consideration  or
combination  thereof,  then and in such  event,  the Limited  Partners  shall be
obligated to take or refrain  from  taking,  as the case may be, such actions as
the plan may provide, including, without limitation, executing such instruments,
and providing such information as the General Partner shall reasonably  request.
Any plan  described  in this  Article  16.7 may also effect an  amendment to the
Partnership Agreement or the adoption of a new partnership agreement as provided
in Section 2.11 of the Act.  The plan may also provide that the General  Partner
and its Affiliates  shall receive fees for services  rendered in connection with
the  operation  of  the  Partnership  or  any  successor  entity  following  the
consummation  of  the  transactions  described  in the  plan,  and  neither  the
Partnership nor the Partners shall have any right by virtue of this Agreement in
the income  derived  therefrom.  Any  securities  or other  consideration  to be
distributed  to the Partners  pursuant to the plan shall be  distributed  in the
manner  set  forth in  Article  24(c)  as  though  the  Partnership  were  being
liquidated.  For this purpose only,  the fair market value of the  securities or
other  consideration  to be  received  pursuant  to the plan shall be treated as
"Profits"  and the capital  accounts of the  Partners  shall be increased in the
manner  provided  in Article  11(a)(ii).  No Partner  shall be  entitled  to any
dissent,  appraisal or similar rights in connection with a plan  contemplated by
this Article 16.7.


                                                       -19-


<PAGE>



                  16.8 Withdrawal of Initial Limited Partner.  Upon the date the
first Limited  Partner is admitted to the Partnership in accordance with Article
10 of this  Agreement,  the Initial  Limited  Partner  shall  withdraw  from the
Partnership,  and thereupon his Capital  Contribution  shall be returned and his
Partnership Interest canceled and reallocated to the Limited Partners.

                  17.      OPTIONAL PURCHASE OF LIMITED PARTNERSHIP INTERESTS
                           --------------------------------------------------
                           ON CERTAIN EVENTS.
                           -----------------

                  17.1 Death. Upon the death of a Limited Partner,  the deceased
Limited  Partner's   executor,   administrator,   or  other  legal  or  personal
representative  shall give written  notice of that fact to the General  Partner.
The General Partner shall have the option to purchase at the Closing (as defined
below) the Partnership Interest of the deceased Limited Partner (whose executor,
administrator  or other  legal or  personal  representative  shall  then  become
obligated  to sell such  Partnership  Interest) at the price  determined  in the
manner  provided  in  Article  17.6  of  this  Agreement  and on the  terms  and
conditions provided in Article 17.7 of this Agreement. The General Partner shall
have a period of thirty (30) days  following  the date of notice of the death of
the Limited Partner (the "Option  Period") within which to notify in writing the
deceased Limited  Partner's  executor,  administrator or other legal or personal
representative,  whether the General Partner wishes to purchase all or a portion
of the  Partnership  Interest of the deceased  Limited  Partner.  If the General
Partner  does not elect to  purchase  the  entire  Partnership  Interest  of the
deceased  Limited  Partner before the expiration of the Option Period and in the
manner provided  herein,  the portion of the Partnership  Interest not purchased
shall be held by the deceased Limited Partner's executor, administrator or other
legal  representative  pursuant  to the  terms of this  Agreement.  The  General
Partner, in its sole discretion,  may elect to assign its rights to purchase the
Partnership  Interest of the deceased Limited Partner under this Article 17.1 to
the Partnership and, in such case, the Partnership shall have the same rights as
provided for the General Partner in this Article 17.1.

                  17.2  Bankruptcy,  Insolvency  or  Assignment  for  Benefit of
Creditors of a Limited  Partner.  In the event that an  involuntary or voluntary
proceeding  under the  Federal  Bankruptcy  Code,  as  amended,  is filed for or
against any Limited Partner,  or if any Limited Partner shall make an assignment
for the benefit of his  creditors,  or if any Limited  Partner has a receiver or
custodian  appointed for his assets,  or any Limited Partner  generally fails to
pay his debts when due, the insolvent  Limited Partner shall give written notice
(the "Notice of Insolvency")  to the General Partner of the  commencement of any
such  proceeding  or the  occurrence of such event within five days of the first
notice to him of such  commencement  or  occurrence  of such event.  The General
Partner shall have the option to purchase at the Closing (as defined  below) the
Partnership  Interest of the  insolvent  Limited  Partner  (which the  insolvent
Limited Partner or his trustee,  custodian,  receiver or other personal or legal
representative,  as the case may be, shall then become obligated to sell) at the
price determined in the manner provided in Article 17.6 of this Agreement and on
the terms and conditions provided in Article 17.7 of this Agreement. The General
Partner shall have a period of thirty (30) days following the date of the Notice
of  Insolvency  (the  "Option  Period")  within  which to notify in writing  the
insolvent Limited Partner or his trustee, custodian, receiver, or other legal or
personal representative, whether the General Partner wishes to purchase all or a
portion of


                                                       -20-


<PAGE>



the  Partnership  Interest  of the  insolvent  Limited  Partner.  If the General
Partner  does not elect to  purchase  the  entire  Partnership  Interest  of the
insolvent  Limited Partner before the expiration of the Option Period and in the
manner provided  herein,  the portion of the Partnership  Interest not purchased
shall be held by the  insolvent  Partner,  his trustee,  custodian,  receiver or
other legal or personal  representative pursuant to the terms of this Agreement.
The General Partner,  in its sole discretion,  may elect to assign its rights to
purchase the  Partnership  Interest of an insolvent  Limited  Partner under this
Article 17.2 to the Partnership  and, in such case, the  Partnership  shall have
the same rights as provided for the General Partner in this Article 17.2.

                  17.3 Breach of Article 14.3. In the event the General  Partner
either  receives a Notice of  Withdrawal as provided in Article 14.3 or receives
notice of a breach of Article 14.3 by or with respect to a Limited  Partner (the
"Competing  Limited  Partner"),  the  General  Partner  may  elect,  in its sole
discretion,  to treat such event as a default  under this  Agreement and enforce
the  provisions of this Article 17.3. If the General  Partner  elects to enforce
the  provisions  of this Article  17.3,  the General  Partner shall give written
notice of such  election  (the  "Notice of Default")  to the  Competing  Limited
Partner  within 180 days of the date the  General  Partner  first  received  the
Notice of  Withdrawal or notice of the  defaulting  event.  The General  Partner
shall  have the  option to  purchase  at the  Closing  (as  defined  below)  the
Partnership  Interest of the  Competing  Limited  Partner  (which the  Competing
Limited Partner shall then become  obligated to sell) at the price determined in
the manner  provided  in  Article  17.6 of this  Agreement  and on the terms and
conditions provided in Article 17.7 of this Agreement. The General Partner shall
have a period of  thirty  (30) days  following  the date it sends the  Notice of
Default (the "Option  Period")  within which to notify in writing the  Competing
Limited  Partner,  whether the  [General  Partner]  wishes to purchase  all or a
portion of the Partnership  Interest of the Competing  Limited  Partner.  If the
General  Partner does not elect to purchase the entire  Partnership  Interest of
the Competing  Limited Partner before the expiration of the Option Period and in
the  manner  provided  herein,  the  portion  of the  Partnership  Interest  not
purchased shall be held by the Competing  Limited Partner  pursuant to the terms
of this Agreement.  The General Partner,  in its sole  discretion,  may elect to
assign its rights to purchase the  Partnership  Interest of a Competing  Limited
Partner  under this  Article  17.3 to the  Partnership  and,  in such case,  the
Partnership  shall have the same rights as provided  for the General  Partner in
this Article 17.3.

                  17.4  Domestic  Proceeding.  In the  event  that a spouse of a
Limited Partner  commences  against a Limited  Partner,  or a Limited Partner is
named in, a Domestic  Proceeding,  the Limited Partner shall give written notice
(the "Notice of Domestic Proceeding") to the General Partner of the commencement
of any such  proceeding  within  five  days of the  first  notice to him of such
commencement.  The  General  Partner  shall have the option to  purchase  at the
Closing  (as defined  below) the  Partnership  Interest  of the Limited  Partner
involved in the Domestic Proceeding (which the Limited Partner shall then become
obligated to sell),  at the price  determined in the manner  provided in Article
17.6 of this Agreement and on the terms and conditions  provided in Article 17.7
of this  Agreement.  The General Partner shall have a period of thirty (30) days
following the date of the Notice of Domestic  Proceeding  (the "Option  Period")
within which to notify in writing the Limited  Partner  involved in the Domestic
Proceeding, whether the General Partner


                                                       -21-


<PAGE>



wishes to purchase all or a portion of the Partnership  Interest of such Limited
Partner.  If the  General  Partner  does not elect to purchase  the  Partnership
Interest of the Limited Partner involved in the Domestic  Proceeding  before the
expiration of the Option Period and in the manner provided  herein,  the portion
of the Partnership  Interest not purchased shall be held by such Limited Partner
pursuant  to the  terms of this  Agreement.  The  General  Partner,  in its sole
discretion,  may elect to assign its rights to purchase the Partnership Interest
of the Limited Partner  involved in the Domestic  Proceeding  under this Article
17.4 to the Partnership  and, in such case, the Partnership  shall have the same
rights as provided for the General Partner in this Article 17.4.

                  17.5 Divestiture  Option.  If state or federal  regulations or
laws are enacted or applied, or if any other legal developments occur, which, in
the opinion of the General Partner  adversely  affect (or potentially  adversely
affect) the operation of the Partnership  (e.g., the enactment or application of
prohibitory physician  self-referral  legislation against the Partnership or its
Partners),  the General Partner shall promptly  either,  in its sole discretion,
(i) take the steps outlined in this Article 17.5 to divest the Limited  Partners
of their Partnership Interests,  or (ii) dissolve the Partnership as provided in
Article  23.1(e).  If the General Partner chooses option (i), it shall deliver a
written  notice to all of the Limited  Partners (the "Notice of  Election")  and
purchase such Partnership  Interests for its own account.  The purchase price to
be paid for each  Partnership  Interest  shall be  determined  in the  manner as
provided in Article 17.6 and shall be on the terms and conditions as provided in
Article  17.7.  The transfer of the  Partnership  Interests,  the payment of the
purchase price and the  assumption of the Limited  Partners'  obligations  under
their respective  Guaranties (as provided in Article 17.6) shall be made at such
time as  determined  by the General  Partner to be in the best  interests of the
Partnership  and its  Limited  Partners.  Each  Limited  Partner  hereby  makes,
constitutes and appoints the General  Partner,  with full power of substitution,
his true and lawful  attorney-in-fact,  to take such  actions and  execute  such
documents  on his behalf to effect the transfer of his  Partnership  Interest as
provided in this Article  17.5.  The  foregoing  power of attorney  shall not be
affected by the  subsequent  incapacity,  mental  incompetence,  dissolution  or
bankruptcy of any Limited Partner.

                  17.6  Purchase  Price.  The purchase  price to be paid for the
Partnership  Interest of any Limited  Partner whose interest is being  purchased
pursuant to the  provisions  of Articles  17.1,  17.2,  17.3,  17.4 or 17.5 (the
"Selling  Limited  Partner")  shall be determined in the manner provided in this
Article 17.6. The purchase price for a Partnership  Interest  purchased pursuant
to the provisions of Articles 17.1,  17.2, 17.3, 17.4 or 17.5 shall be an amount
equal to the Limited Partner's share of the Partnership's book value, if any, as
reflected  by  the  Limited   Partner's   capital  account  in  the  Partnership
(unadjusted  for any  appreciation  in  Partnership  assets  and as  reduced  by
depreciation  deductions  claimed by the Partnership for tax purposes) as of the
Valuation  Date. The Valuation Date means the last day of the month  immediately
preceding the month in which occurs: (i) the death of a Selling Limited Partner,
in the case of a purchase by reason of death;  (ii) the bankruptcy or insolvency
of a  Selling  Limited  Partner  in the case of a  purchase  by  reason  of such
bankruptcy or insolvency; (iii) the Notice of Withdrawal or breach of Article 14
as provided in Article  17.3 in the case of a purchase by reason  thereof;  (iv)
the commencement of the Domestic Proceeding, in the case of a purchase by reason
thereof; or (v) the Notice of Election as provided in Article 17.5, in the


                                                       -22-


<PAGE>



in the  case  of a  purchase  by  reason  thereof.  Any  Limited  Partner  whose
Partnership  Interest is purchased  pursuant to the  provisions of Article 17.1,
17.2,  17.3,  17.4 or 17.5 shall be entitled  only to the  purchase  price which
shall be paid at the Closing in cash (or by certified  or  cashier's  check) and
shall not be entitled to any Partnership  distributions made after the Valuation
Date.  The  Partnership  shall  have the right to deduct  the amount of any such
distributions  made to the Selling Limited Partner after the Valuation Date from
the purchase price. The transfer of a Partnership  Interest of a Selling Limited
Partner  shall be  deemed to occur as of the  valuation  Date,  and the  Selling
Limited  Partner shall have no voting or other rights as a Limited Partner after
such date.  Such price is likely to be  considerably  less than the fair  market
value of the Limited  Partner's  interest in the Partnership and may not provide
any positive return on the Limited  Partner's  investment.  Because  Partnership
losses,  depreciation  deductions and Distributions reduce capital accounts, and
because appreciation in Partnership assets is not reflected in capital accounts,
it is the opinion of the General  Partner that the option purchase price will be
nominal in amount.

                  17.7     Closing.
                           -------

                  17.7.1  Closing  of  Purchase  and Sale.  The  Closing  of any
         purchase and sale of a Partnership  Interest  pursuant to Article 17.1,
         17.2,  17.3,  17.4 or 17.5 of this  Agreement  shall  take place at the
         principal office of the Partnership,  or such other place designated by
         the General Partner, on the date determined as follows (the "Closing"):

                           (a) In the case of a purchase  and sale  occurring by
         reason of the death of a Limited Partner as provided in Article 17.1 of
         this  Agreement,  the Closing shall be held on the thirtieth day (or if
         such  thirtieth  day is not a  business  day,  the  next  business  day
         following the thirtieth day) next following the last to occur of:

               (i)  Qualification  of the executor or personal  administrator of
          the deceased Limited Partner's estate;

               (ii)  The  date  on  which  any  necessary  determination  of the
          purchase  price of the  Partnership  Interest to be purchased has been
          made; or

               (iii)  The  date  that  coincides  with the  close of the  Option
          Period.

                           (b) In the case of a purchase  and sale  occurring by
         reason of the  occurrence  of one of the  events  described  in Article
         17.2,  17.3, 17.4 or 17.5 of this Agreement,  the Closing shall be held
         on the thirtieth  day (or if such  thirtieth day is not a business day,
         the next business day following the thirtieth  day) next  following the
         later to occur of:


                                                       -23-


<PAGE>



               (i) The date on which any necessary determination of the purchase
          price of the Partnership Interest to be purchased has been made; or

               (ii) The date that coincides with the close of the Option Period.

         At the Closing,  although not  necessary  to effect the  transfer,  the
         Selling Limited Partner shall  concurrently  with tender and receipt of
         the applicable  purchase price,  deliver to the purchaser duly executed
         instruments of transfer and  assignment,  assigning good and marketable
         title to the  portion or  portions  of the  Selling  Limited  Partner's
         entire  Partnership  Interest thus  purchased,  free and clear from any
         liens  or  encumbrances  or  rights  of  others  therein.  The  parties
         acknowledge  that occurrence of any of the triggering  events described
         in Article 17.1,  17.2,  17.3, 17.4 or 17.5 and compliance with all the
         Articles  of this  Agreement,  except  the  execution  of the  transfer
         documents  by the Selling  Limited  Partner as  provided  above in this
         Article 17.7.1,  are sufficient to effect the complete  transfer of the
         Selling Limited Partner's  Partnership Interest and the Selling Limited
         Partner shall be deemed to consent to admission of the  transferee as a
         substitute Limited Partner.  Notwithstanding the date of the Closing or
         whether a Closing is  successfully  held, the transfer of a Partnership
         Interest of a Selling  Limited  Partner  shall be deemed to occur as of
         the Valuation Date as defined in Article 17.6.  The deemed  transfer is
         effective  regardless of whether the Selling Limited  Partner  performs
         the duties set forth in this Article 17.7.1.

                           (c) In case of a purchase  occurring by reason of the
         occurrence of an event  described in Article 17.5, the Closing shall be
         held as soon as possible  following the  determination  of the purchase
         price.

                  17.7.2  Terms and  Conditions  of  Purchase.  The  Partnership
         Interest of a Limited  Partner shall not be  transferred to any Partner
         unless the  requirements  of Articles 16.2 and 16.4 (b) through (f) are
         satisfied  with  respect to it. The  purchaser  shall be liable for all
         obligations  and  liabilities   connected  with  that  portion  of  the
         Partnership  Interest  transferred  to it  unless  otherwise  agreed in
         writing.

                  18.      SALE, ASSIGNMENT OR OTHER TRANSFER OF THE GENERAL
                           -------------------------------------------------
                           PARTNER'S INTEREST.
                           ------------------

                  18.1  The   General   Partner   may  not   mortgage,   pledge,
hypothecate,  transfer,  sell, assign or otherwise dispose of all or any part of
its interest in the  Partnership,  whether  voluntarily,  by operation of law or
otherwise (the foregoing  actions being  hereafter  collectively  referred to as
"Transfers" or singularly as a "Transfer") except as permitted by this Article.


                                                       -24-


<PAGE>



                  18.2 If the  General  Partner  makes a Transfer  (other than a
mortgage,  pledge or  hypothecation)  of its  general  partner  interest  in the
Partnership pursuant to this Article, it shall be liable for all obligations and
liabilities  incurred  by it as the  general  partner of the  Partnership  on or
before  the  effective  date of such  Transfer,  but shall not be liable for any
obligations or liabilities of the  Partnership  arising after the effective date
of the Transfer.

          18.3 No Transfer by the General Partner shall be permitted unless:

                           (a) Counsel for the  Partnership  shall have rendered
         an  opinion  that none of the  actions  taken in  connection  with such
         Transfer will cause the  Partnership  to be classified  other than as a
         partnership   for  federal  income  tax  purposes  or  will  cause  the
         termination or dissolution of the Partnership under state law; and

                           (b)  Such  documents  or  instruments,  in  form  and
         substance satisfactory to counsel for the Partnership,  shall have been
         executed and delivered as may be required in the opinion of counsel for
         the Partnership to effect fully any such Transfer.

                  Notwithstanding the foregoing provisions of this Article 18.3,
the General  Partner may pledge its  interest  in the  Partnership  to any bank,
insurance   company  or  other  financial   institution  to  secure  payment  of
indebtedness.

                  19.      TERMINATION OF THE SERVICES OF THE GENERAL PARTNER.
                           --------------------------------------------------

                  If the General Partner shall be finally adjudged by a court of
competent  jurisdiction to be liable to the Limited  Partners or the Partnership
for any act of gross negligence or willful  misconduct in the performance of its
duties under the terms of this Agreement, the General Partner may be removed and
another  substituted  with the  consent  of all of the  Limited  Partners.  Such
consent  shall be evidenced  by a  certificate  of removal  signed by all of the
Limited Partners. In the event of removal, the new general partner shall succeed
to all of the powers, privileges and obligations of the General Partner, and the
General  Partner's  interest in the  Partnership  shall become that of a Limited
Partner,  and the General Partner shall maintain its same Percentage Interest in
the Partnership  notwithstanding  anything contained in the Act to the contrary.
In addition,  in the event of removal,  the new general  partner  shall take all
steps  necessary  and  appropriate  to prepare  and record an  amendment  to the
Certificate of Limited Partnership to reflect the removal of the General Partner
and the admission of such new general partner.

                  20.      MANAGEMENT AND OPERATION OF BUSINESS.
                           ------------------------------------

                  20.1 All  decisions  with  respect  to the  management  of the
business and affairs of the Partnership shall be made by the General Partner.


                                                       -25-


<PAGE>



                  20.2 The General  Partner shall be under no duty to devote all
of its time to the business of the Partnership,  but shall devote only such time
as it deems  necessary  to conduct the  Partnership  business and to operate and
manage the Partnership in an efficient manner.

                  20.3 The  General  Partner may charge to the  Partnership  all
ordinary and necessary costs and expenses, direct and indirect,  attributable to
the activities,  conduct and management of the business of the Partnership.  The
costs and expenses to be borne by the  Partnership  shall  include,  but are not
limited to, all  expenditures  incurred in acquiring and financing the Equipment
or other Partnership property, legal and accounting fees and expenses,  salaries
of employees of the Partnership,  consulting and quality  assurance fees paid to
independent contractors, insurance premiums and interest.

                  20.4 In addition to, and not in limitation  of, any rights and
powers  covenanted by law or other  provisions of this Agreement,  and except as
limited,  restricted or prohibited by the express  provisions of this Agreement,
the General Partner shall have and may exercise on behalf of the Partnership all
powers and rights necessary,  proper,  convenient or advisable to effectuate and
carry out the purposes, business and objectives of the Partnership.  Such powers
shall include, without limitation, the following:

               (a) To conduct the Offering  and any Dilution  Offering on behalf
          of the Partnership;

                           (b) To acquire on behalf of the  Partnership  (i) one
         or  more  Prostatron(R)  Mobile  Systems;  (ii)  any  other  urological
         device(s)  or  equipment  so  long  as such  device  has FDA  premarket
         approval at the time it is required  by the  Partnership;  or (iii) any
         other assets or equipment or an interest in another  entity  consistent
         with  the  purposes  of  the  Partnership  as  provided  in  Article  4
         (collectively,  the  "Additional  Assets"),  at such  times and at such
         price and upon such terms,  as the General  Partner  deems to be in the
         best interest of the Partnership;

                           (c) To purchase,  hold,  manage,  lease,  license and
         dispose of Partnership assets, including the purchase,  exchange, trade
         or sale of the Partnership's assets at such price, or amount, for cash,
         securities  or other  property  and upon  such  terms,  as the  General
         Partner deems to be in the best interest of the Partnership;  provided,
         that  should  the  Partnership   assets  be  exchanged  or  traded  for
         securities or other property (the  "Replacement  Property") the General
         Partner  shall  have the same  powers  with  regard to the  Replacement
         Property as it does towards the traded property;

               (d)  To  exercise  the  option  of  the  General  Partner  or the
          Partnership  to  purchase  a Limited  Partner's  Partnership  Interest
          pursuant to Article 17;



                                                       -26-


<PAGE>



               (e) To determine the travel  itinerary and site locations for the
          Prostatron(R)Mobile System or other Partnership technology;

                           (f) To  borrow  money  for  any  Partnership  purpose
         (including the  acquisition of the Additional  Assets) and, if security
         is required therefor,  to subject to any security device any portion of
         the property for the Partnership,  to obtain  replacements of any other
         security device, to prepay, in whole or in part,  refinance,  increase,
         modify, consolidate or extend any encumbrance or other security device;

                           (g)  To  deposit,   withdraw,   invest,  pay,  retain
         (including  the  establishment  of  reserves  in order to  acquire  the
         Additional Assets) and distribute the Partnership's funds in any manner
         consistent with the provisions of this Agreement;

               (h) To institute and defend actions at law or in equity;

                           (i)  To  enter  into  and  carry  out  contracts  and
         agreements and any or all documents and  instruments  and to do any and
         all such other things as may be in furtherance of Partnership  purposes
         or  necessary  or  appropriate  to  the  conduct  of  the   Partnership
         activities;

               (j) To execute,  acknowledge  and deliver any and all instruments
          which may be deemed necessary or convenient to effect the foregoing;

                           (k) To  engage  or  retain  one or  more  persons  to
         perform   acts  or  provide   materials  as  may  be  required  by  the
         Partnership,  at the  Partnership's  expense,  and to  compensate  such
         person or persons at a rate to be set by the General Partner,  provided
         that the  compensation  is at the then  prevailing rate for the type of
         services  and  materials  provided,  or both.  Any  person,  whether  a
         Partner,  an Affiliate  of a Partner or  otherwise,  including  without
         limitation  the  General  Partner,  may be  employed  or engaged by the
         Partnership to render services and provide  materials,  including,  but
         not limited to, management services,  professional services, accounting
         services,  quality  assessment  services,  legal  services,   marketing
         services, maintenance services or provide materials; and if such person
         is a Partner or an Affiliate of a Partner,  (s)he shall be entitled to,
         and shall be paid compensation for said services or materials, anything
         in this  Agreement to the contrary  notwithstanding,  provided that the
         compensation   to  be  received  for  such  services  or  materials  is
         competitive in price and terms with then  prevailing  rate for the type
         of services and/or materials provided. The Partnership, pursuant to the
         terms of a Management Agreement, will contract with the General Partner
         with respect to the supervision and  coordination of the management and
         administration  of  the  day-to-day  operations  of  the  Partnership's
         business  for a  monthly  fee  equal  to the  greater  of  7.5%  of net
         Partnership  Cash Flow per month or $8,000 per month  (beginning  as of
         the Closing  Date but not to be paid for more than four  months  before
         the month in which Partnership's treatment


                                                       -27-


<PAGE>



         operations  commence).  All costs incurred by the General Partner under
         the Management Agreement shall be paid or reimbursed by the Partnership
         directly.  The Partnership may also contract with healthcare facilities
         and/or qualified  physicians  desiring to use its Prostatron(R)  Mobile
         System  for the  treatment  of  patients.  Owning  an  interest  in the
         Partnership shall not be a condition to using the Prostatron(R)  Mobile
         System. The General Partner and its Affiliates may engage in or possess
         an interest in other  business  ventures of any nature and  description
         independently  or with  others,  including,  but not  limited  to,  the
         operation  of a  fixed-base  or mobile  TUMT unit,  whether or not such
         business  ventures  are in  direct  or  indirect  competition  with the
         Partnership,  and neither the  Partnership  nor the Partners shall have
         any  right  by  virtue  of this  Agreement  in and to said  independent
         ventures or to the income or profits derived therefrom.

                  20.5  In  addition  to  other  acts  expressly  prohibited  or
restricted  by this  Agreement  or by law,  the  General  Partner  shall have no
authority to act on behalf of the Partnership in:

               (a)  Doing  any act in  contravention  of this  Agreement  or the
          Partnership's Certificate of Limited Partnership;

               (b) Doing any act which would make it  impossible to carry on the
          ordinary business of the Partnership;

               (c)  Possessing or in any manner  dealing with the  Partnership's
          property  or  assigning   the  rights  of  the   Partnership   in  the
          Partnership's property for other than Partnership purposes;

               (d) Admitting a person as a Limited  Partner or a General Partner
          except as provided in this Agreement; or

                           (e) Performing any act (other than an act required by
         this  Agreement or any act taken in good faith  reliance upon counsel's
         opinion)  which  would,  at the time  such act  occurred,  subject  any
         Limited Partner to liability as a general partner in any jurisdiction.

                  21.      RESERVES.
                           --------

                  The  General  Partner  may cause the  Partnership  to create a
reserve account to be used exclusively for repairs and acquisition of Additional
Assets and for any other valid Partnership  purpose.  The General Partner shall,
in its sole discretion, determine the amount of payments to such reserve.


                                                       -28-


<PAGE>



                  22.      INDEMNIFICATION AND EXCULPATION OF THE GENERAL
                           PARTNER.

                  22.1 The General  Partner is accountable to the Partnership as
a fiduciary and consequently  must exercise good faith and integrity in handling
Partnership  affairs.  The  General  Partner  and its  Affiliates  shall have no
liability to the  Partnership  which arises out of any action or inaction of the
General Partner or its Affiliates if the General  Partner or its Affiliates,  in
good faith,  determined  that such course of conduct was in the best interest of
the Partnership and such course of conduct did not constitute  gross  negligence
or willful  misconduct  of the General  Partner or its  Affiliates.  The General
Partner and its Affiliates  shall be indemnified by the Partnership  against any
losses, judgments,  liabilities,  expenses and amounts paid in settlement of any
claims sustained by them in connection with the  Partnership,  provided that the
same were not the result of gross  negligence or willful  misconduct on the part
of the General Partner or its Affiliates.

                  22.2 The General Partner shall not be liable for the return of
the Capital Contributions of the Limited Partners, and upon dissolution, Limited
Partners shall look solely to the assets of the Partnership.

                  23.      DISSOLUTION OF THE PARTNERSHIP.
                           ------------------------------

               23.1 The  Partnership  shall be dissolved and  terminated and its
          business  wound up upon  the  occurrence  of any one of the  following
          events:

                           (a) The expiration of its term on December 31, 2047;

                           (b) The  filing  by, on behalf  of,  or  against  the
         General Partner of any petition or pleading,  voluntary or involuntary,
         to declare the General  Partner  bankrupt  under any  bankruptcy law or
         act, or the  commencement in any court of any proceeding,  voluntary or
         involuntary,  to declare the General Partner insolvent or unable to pay
         its debts, or the appointment by any court or supervisory  authority of
         a  receiver,  trustee or other  custodian  of the  property,  assets or
         business of the General  Partner or the  assignment by it of all or any
         part of its  property or assets for the benefit of  creditors,  if said
         action,  proceeding  or  appointment  is  not  dismissed,   vacated  or
         otherwise terminated within ninety (90) days of its commencement;

               (c) The determination of the General Partner that the Partnership
          should be dissolved;

                           (d) The  occurrence  of an event  described in a plan
         approved  by the  General  Partner  and a Majority  in  Interest of the
         Limited Partners  pursuant to Article 16.7 resulting in the dissolution
         of the Partnership;


                                                       -29-


<PAGE>



               (e)  The  election  of  the  General   Partner  to  dissolve  the
          Partnership  following the occurrence of an event described in Article
          17.5;

                           (f) Except as otherwise provided in any plan approved
         by the  General  Partner  and a Majority  in  Interest  of the  Limited
         Partners  pursuant  to  Article  16.7,  the  sale,  exchange  or  other
         disposition  of  all  or  substantially  all  of  the  property  of the
         Partnership without making provision for the replacement thereof; or

                           (g) The dissolution,  retirement, resignation, death,
         disability  or legal  incapacity  of a general  partner,  and any other
         event  resulting in the  dissolution or termination of the  Partnership
         under the laws of the State of Texas.

                  23.2  Notwithstanding  the  provisions  of Article  23.1,  the
Partnership   shall  not  be  dissolved  and  terminated  upon  the  retirement,
resignation,  bankruptcy,  assignment for the benefit of creditors, dissolution,
death,  disability or legal  incapacity of a general  partner,  and its business
shall continue  pursuant to the terms and conditions of this  Agreement,  if any
general partner or general partners remain  following such event;  provided that
such  remaining  general  partner or general  partners  are hereby  obligated to
continue the business of the  Partnership.  If no general  partner remains after
the  occurrence of such event,  the business of the  Partnership  shall continue
pursuant to the terms and conditions of this  Agreement,  if, within ninety (90)
days after the  occurrence of such event,  a Majority in Interest of the Limited
Partners agree in writing to continue the business of the  Partnership,  and, if
necessary,  to  the  appointment  of one  or  more  persons  or  entities  to be
substituted as the general  partner.  In the event the Limited Partners agree as
provided  above to continue  the  business of the  Partnership,  the new general
partner or general  partners shall succeed to all of the powers,  privileges and
obligations of the General Partner,  and the General  Partner's  interest in the
Partnership shall become a Limited Partner's interest hereunder. Furthermore, in
the event a remaining general partner or the Limited  Partners,  as the case may
be, agree to continue the business of the  Partnership as provided  herein,  the
remaining  general  partner or the newly  appointed  general  partner or general
partners,  as the case may be, shall take all steps necessary and appropriate to
prepare and record an amendment to the  Certificate  of Limited  Partnership  to
reflect the continuation of the business of the Partnership and the admission of
a new general partner or general partners, if any.

                  24.      DISTRIBUTION UPON DISSOLUTION.
                           -----------------------------

                  Upon the dissolution and termination of the  Partnership,  the
General Partner or, if there is none, a representative  of the Limited Partners,
shall  cause  the  cancellation  of the  Partnership's  Certificate  of  Limited
Partnership,  shall liquidate the assets of the Partnership, and shall apply and
distribute the proceeds of such liquidation in the following order of priority:

               (a) First,  to the  payment of the debts and  liabilities  of the
          Partnership, and the expenses of liquidation;



                                                       -30-


<PAGE>



                           (b) Second, to the creation of any reserves which the
         General Partner (or such  representatives  of the Limited Partners) may
         deem  reasonably  necessary  for  the  payment  of  any  contingent  or
         unforeseen  liabilities  or  obligations  of the  Partnership or of the
         General  Partner  arising out of or in connection with the business and
         operation of the Partnership; and

                           (c) Third, the balance,  if any, shall be distributed
         to the  Partners in  accordance  with the  Partners'  positive  Capital
         Account  balances after such Capital  Accounts are adjusted as provided
         by Article 12, and any other adjustments required by the Final Treasury
         Regulations  under Section 704(b) of the Code. Any general partner with
         a negative  Capital Account  following the  distribution of liquidation
         proceeds or the  liquidation  of its interest  must  contribute  to the
         Partnership  an amount  equal to such  negative  Capital  Account on or
         before the end of the Partnership's  taxable year (or, if later, within
         ninety days after the date of liquidation).  Any capital so contributed
         shall  be (i)  distributed  to those  Partners  with  positive  Capital
         Accounts until such Capital  Accounts are reduced to zero,  and/or (ii)
         used to discharge recourse liabilities.

                  25.      BOOKS OF ACCOUNT, RECORDS AND REPORTS.
                           -------------------------------------

                  25.1 Proper and complete records and books of account shall be
kept by the General  Partner in which shall be entered fully and  accurately all
transactions  and such other matters relating to the  Partnership's  business as
are usually  entered  into  records and books of account  maintained  by persons
engaged  in  businesses  of a like  character.  The  books  and  records  of the
Partnership  shall be prepared  according to the accounting method determined by
the General Partner.  The Partnership's  fiscal year shall be the calendar year.
The books and  records  shall at all times be  maintained  at the  Partnership's
Records Office and shall be open to the reasonable inspection and examination of
the Partners or their duly authorized representatives during reasonable business
hours.

                  25.2 Within  ninety (90) days after the end of each Year,  the
General  Partner shall send to each person who was a Limited Partner at any time
during such year such tax information,  including,  without limitation,  federal
tax Schedule K-1, as shall be reasonably  necessary for the  preparation by such
person of his or her federal  income tax return.  The General  Partner will also
make  available to the Limited  Partners any other  information  required by the
Act.

                  25.3 The General  Partner shall maintain at the  Partnership's
Records  Office  copies of the  Partnership's  original  Certificate  of Limited
Partnership   and  any  certificate  of  amendment,   restated   certificate  or
certificate of cancellation with respect thereto and such other documents as the
Act shall require.  The General Partner will furnish to any Limited Partner upon
request or as  otherwise  required by law a copy of the  Partnership's  original
Certificate of Limited  Partnership and any  certificate of amendment,  restated
certificate, or certificate of cancellation, if any.


                                                       -31-


<PAGE>



                  25.4 The General Partner shall, in its sole  discretion,  make
for the  Partnership  any and all  elections  for  federal,  state and local tax
purposes including, without limitation, any election, if permitted by applicable
law, to adjust the basis of the Partnership's property pursuant to Code Sections
754,  734(b) and  743(b),  or  comparable  provisions  of state or local law, in
connection  with  transfers  of  interests in the  Partnership  and  Partnership
Distributions.

                  25.5 The  General  Partner is  designated  as the Tax  Matters
Partner  (as  defined  in  Section  6231 of the Code) and to act in any  similar
capacity  under  state or local law,  and is  authorized  (at the  Partnership's
expense):   (i)  to  represent  the   Partnership  and  Partners  before  taxing
authorities  or courts of competent  jurisdiction  in tax matters  affecting the
Partnership  or  Partners  in their  capacity  as  Partners;  (ii) to extend the
statute of limitations for assessment of tax deficiencies  against Partners with
respect to adjustments to the Partnership's federal, state or local tax returns;
(iii) to execute any agreements or other documents relating to or affecting such
tax matters, including agreements or other documents that bind the Partners with
respect to such tax matters or  otherwise  affect the rights of the  Partnership
and Partners; and (iv) to expend Partnership funds for professional services and
costs  associated  therewith.  The General Partner is authorized and required to
notify the federal,  state or local tax  authorities of the appointment of a Tax
Matters  Partner  in  the  manner  provided  in  Treasury   Regulations  Section
301.6231(a)(7)-1,  as modified from time to time. In its capacity as Tax Matters
Partner,  the General Partner shall oversee the Partnership's tax affairs in the
manner which, in its best judgment, is in the interests of the Partners.

                  26.      NOTICES.
                           -------

                  All notices under this Agreement shall be in writing and shall
be deemed to have been given when delivered  personally,  or mailed by certified
or registered mail, postage prepaid,  return receipt  requested.  Notices to the
General  Partner  shall be  delivered  at, or mailed to, its  principal  office.
Notices to the  Partnership  shall be delivered  at, or mailed to, its principal
office with a copy to each of its business offices.  Notice to a Limited Partner
shall be  delivered  to such  Limited  Partner,  or mailed  to the last  address
furnished  by him or her for  such  purposes  to the  General  Partner.  Limited
Partners shall give notice of a change of address to the General  Partner in the
manner provided in this Article.

                  27.      AMENDMENTS.
                           ----------

                  Subject to the  provisions  of Article 28, this  Agreement  is
subject to  amendment  only by  written  consent of the  General  Partner  and a
Majority in Interest of the Limited Partners;  provided, however, the consent of
the Limited Partners shall not be required if such amendments are ministerial in
nature and do not contravene the provisions of Article 28.  Further,  no Limited
Partner  consent shall be required to amend  Schedule A to reflect the admission
of  Partners  as  contemplated  by the  Offering,  any  Dilution  Offering or as
otherwise herein permitted.


                                                       -32-


<PAGE>



                  28.      LIMITATIONS ON AMENDMENTS.
                           -------------------------

                  Notwithstanding  the provisions of Article 27, no amendment to
this Agreement shall:

                           (a) Enlarge the obligations of any Partner under this
         Agreement  or convert the  interest in the  Partnership  of any Limited
         Partner  into the  interest of a general  partner or modify the limited
         liability of any Limited Partner, without the consent of such Partner;

                           (b) Amend the  provisions of Article 12, 13, 15 or 24
         without the approval of the General  Partner and a Majority in Interest
         of the Limited Partners;  provided,  however,  that the General Partner
         may at any time amend such Articles  without the consent of the Limited
         Partners in order to permit the Partnership allocations to be sustained
         for federal  income tax  purposes,  but only if such  amendments do not
         materially  affect  adversely the rights and obligations of the Limited
         Partners, in which case such amendments may only be made as provided in
         this Article 28(b); or

               (c) Amend this Article 28 without the consent of all Partners.

                  29.      MEETINGS, CONSENTS AND VOTING.
                           -----------------------------

                  29.1 A meeting of the  Partnership to consider any matter with
respect to which the  Partners  may vote as set forth in this  Agreement  may be
called  by the  General  Partner  or by  Limited  Partners  who hold  more  than
twenty-five  percent (25%) of the aggregate interests in the Partnership held by
all the Limited Partners.  Upon receipt of a notice requesting a meeting by such
Partner or Partners and stating the purpose of the meeting,  the General Partner
shall, within ten (10) days thereafter, give notice to the Partners of a meeting
of the  Partnership to be held at a time and place  generally  convenient to the
Limited  Partners on a date not earlier than fifteen (15) days after  receipt by
the  General  Partner of the  notice  requesting  a  meeting.  The notice of the
meeting shall set forth the time, date, location and purpose of the meeting.

     29.2 Any consent of a Partner  required by this  Agreement  may be given as
follows:

     (a) By a written  consent given by the  consenting  Partner and received by
the  General  Partner at or prior to the doing of the act or thing for which the
consent is solicited, or

                           (b) By the affirmative vote by the consenting Partner
         to the doing of the act or thing for which the consent is  solicited at
         any meeting  called  pursuant to this  Article to consider the doing of
         such act or thing.


                                                      -33-


<PAGE>



                  29.3 When exercising voting rights expressly granted under the
Articles of this  Agreement,  each Partner shall have that number of votes as is
equal to the  Percentage  Interest  of such  Partner  at the  time of the  vote,
multiplied by 100.

                  30.      SUBMISSIONS TO THE LIMITED PARTNERS.
                           -----------------------------------

                  The General Partner shall give the Limited  Partners notice of
any proposal or other matter  required by any provision of this  Agreement or by
law to be submitted for consideration and approval of the Limited Partners. Such
notice shall include any  information  required by the relevant  provision or by
law.

                  31.      ADDITIONAL DOCUMENTS.
                           --------------------

                  Each  party  hereto  agrees to  execute  and  acknowledge  all
documents and writings which the General Partner may deem necessary or expedient
in the creation of this Partnership and the achievement of its purpose.

                  32.      SURVIVAL OF RIGHTS.
                           ------------------

                  Except as herein  otherwise  provided  to the  contrary,  this
Agreement  shall be binding upon and inure to the benefit of the parties hereto,
their successor and assigns.

                  33.      INTERPRETATION AND GOVERNING LAW.
                           --------------------------------

                  When the  context  in which  words are used in this  Agreement
indicates  that such is the intent,  words in the singular  number shall include
the plural and vise versa; in addition,  the masculine  gender shall include the
feminine and neuter  counterparts.  The Article headings or titles and the table
of  contents  shall not define,  limit,  extend or  interpret  the scope of this
Agreement  or any  particular  Article.  This  Agreement  shall be governed  and
construed  in  accordance  with the laws of the  State of Texas  without  giving
effect to the conflicts of laws provisions thereof.

                  34.      SEVERABILITY.
                           ------------

                  If any provision,  sentence,  phrase or word of this Agreement
or the application  thereof to any person or circumstance shall be held invalid,
the remainder of this Agreement, or the application of such provision, sentence,
phrase, or word to persons or circumstances,  other than those as to which it is
held invalid, shall not be affected thereby.

                  35.      AGREEMENT IN COUNTERPARTS.
                           -------------------------

                  This Agreement may be executed in several  counterparts,  each
of which shall be deemed an original,  but all of which shall constitute one and
the same  instrument.  In  addition,  this  Agreement  may contain more than one
counterpart of the signature page and this Agreement may


                                                       -34-


<PAGE>



be executed by the affixing of the  signatures of each of the Partners to one of
such  counterpart  signature pages; all of such signature pages shall be read as
though  one,  and they shall have the same force and effect as though all of the
signers had signed a single signature page.

                  36.      THIRD PARTIES.
                           -------------

                  The agreements, covenants and representations contained herein
are for the benefit of the parties  hereto  inter se and are not for the benefit
of any  third  parties  including,  without  limitation,  any  creditors  of the
Partnership.

                  37.      POWER OF ATTORNEY.
                           -----------------

                  Each Limited  Partner hereby makes,  constitutes  and appoints
Joseph  Jenkins,  M.D.  and David  Vela,  M.D.,  severally,  with full  power of
substitution,  his or her true and lawful attorneys- in-fact, for him or her and
in his or her name,  place and stead and for his or her use and  benefit to sign
and acknowledge,  file and record,  any amendments hereto among the Partners for
the further  purpose of executing and filing on behalf of each Limited  Partner,
any and all certificates of limited  partnership or other documents necessary to
constitute the Partnership or to effect the continuation of the Partnership, the
admission  or  withdrawal  of a  general  partner  or  a  limited  partner,  the
qualification of the Partnership in a foreign jurisdiction (or amendment to such
qualification),  the admission of substitute Limited Partners or the dissolution
or  termination  of the  Partnership,  provided  such  continuation,  admission,
withdrawal, qualification, or dissolution and termination are in accordance with
the terms of this Agreement.

                  The foregoing power of attorney is a special power of attorney
coupled with an interest,  is  irrevocable  and shall  survive the death,  legal
incapacity,  dissolution  or  bankruptcy  of  each  Limited  Partner.  It may be
exercised by any one of said  attorneys  by listing all of the Limited  Partners
executing any instrument over the signature of the  attorney-in-fact  acting for
all of them.  The power of attorney  shall survive the delivery of an assignment
by a Limited  Partner of the whole or any  portion of his or her Unit.  In those
cases in which the assignee of, or the successor to, a Limited  Partner owning a
Unit has been  approved by the Partners for  admission to the  Partnership  as a
substitute  Limited  Partner,  the power of attorney  shall survive for the sole
purpose of enabling  the General  Partner to execute,  acknowledge  and file any
instrument necessary to effect such substitution.

                  This power of attorney shall not be affected by the subsequent
bankruptcy,  dissolution,  incapacity  or  mental  incompetence  of any  Limited
Partner.

                  38.      ARBITRATION.
                           -----------

                  Any  dispute  arising  out  of  or  in  connection  with  this
Agreement or the breach thereof shall be decided by arbitration in Austin, Texas
in accordance with the then effective commercial


                                                       -35-


<PAGE>



arbitration rules of the American Arbitration Association,  and judgment thereof
may be entered in any court having jurisdiction thereof.

                  39.      CREDITORS.
                           ---------

                  None of the  provisions  of this  Agreement  shall  be for the
benefit of or enforceable by any creditors of the Partnership.

                                             [signature page follows]



                                                       -36-


<PAGE>



                  IN WITNESS  WHEREOF,  the parties have executed this Agreement
of Limited Partnership as of the day and year first above written.

                                                     GENERAL PARTNER:

                                                By:      PROSTATHERAPIES, INC.,
                                                         a Delaware corporation


                                                     By:/s/ Joseph Jenkins, M.D.
                                                     ---------------------------
                                                         Joseph Jenkins, M.D.
                                                         President


ATTEST:

_________________________                                  [CORPORATE SEAL]
Secretary

                                                     INITIAL LIMITED PARTNER:
                                                     -----------------------


                                                     /s/ James Cochran, M.D.
                                                     -----------------------
                                                     James Cochran, M.D.




                                                       -37-


<PAGE>



STATE OF ____________________)
                                            )
COUNTY OF __________________                         )

                  On this  _______  day of  ___________,  _____,  before me, the
undersigned  Notary Public in and for the County of _______________ in the State
of ___________________________, personally came Joseph Jenkins, M.D., who, being
by me duly sworn, said that he is President of  Prostatherapies,  Inc., the sole
general  partner of Texas I  Prostatherapy  Limited  Partnership,  that the seal
affixed to the  foregoing  instrument  in writing is the  corporate  seal of the
corporation,  and that said  writing was signed,  sworn to, and sealed by him in
behalf  of said  corporation  by its  authority  duly  given.  And the said Stan
Johnson, further certified that the facts set forth in said writing are true and
correct,  and  acknowledged  said  instrument  to be the  act  and  deed of said
corporation.

                  WITNESS my hand and notarial seal.

                                                     Notary Public

My commission expires:

- ---------------------------



STATE OF ________________                   )
                                            )
COUNTY OF ______________                    )

                  I, _______________________________, a notary public in and for
the State and County set forth  above,  do hereby  certify  that James  Cochran,
M.D.,  personally appeared before me this _____ day of _____________,  _____ and
acknowledged and swore to the due execution of the foregoing Limited Partnership
Agreement in his capacity as the initial limited partner.

                                                     Notary Public

My commission expires:

- ---------------------------





                                                       -38-


<PAGE>



                           COUNTERPART SIGNATURE PAGE

                  By signing this  Counterpart  Signature  Page, the undersigned
acknowledges  his or  her  acceptance  of  that  certain  Agreement  of  Limited
Partnership  of  Texas  I  Prostatherapy  Limited  Partnership,  and  his or her
intention to be legally bound thereby.

                  Dated this _________ day of ___________________, _______.




                                                     Signature

                                                     Printed Name

STATE OF _______________                    )
                                            )
COUNTY OF _____________                     )


                  BEFORE ME, the undersigned  Notary Public in and for the State
and County set forth  above,  on the _______ day of  __________________,  _____,
personally appeared ___________________________________,  and, being by me first
duly sworn,  stated that (s)he signed this  Counterpart  Signature  Page for the
purpose set forth above and that the statements contained therein are true.

                                                     Signature of Notary Public

                                                     Printed Name of Notary

My Commission Expires:

- ---------------------------
[SEAL]

                                                       -39-


<PAGE>
                                  SCHEDULE A-1


                        Schedule of Partnership Interests

                    Texas I Prostatherapy Limited Partnership

           CONTRIBUTIONS OF CAPITAL TO THE PARTNERSHIP AND GUARANTIES

                                  Cash Contribution         Percentage Interest

General Partner

Prostatherapies, Inc.                  $147,488                      20
1301 Capital of Texas Highway
Suite C-300
Austin, TX  78746

Limited Partners

Danilo Asase                              1,875                      0.25
Charles Bamberger                        30,000                      4
Marc T. Barrett                           1,875                      0.25
Steve Best                                7,500                      1
Christopher Brehm                         7,500                      1
Robert M. Brenner                         7,500                      1
James Cochran                            30,000                      4
Robert Corwin                             3,750                      0.5
Stephen Corwin                            3,750                      0.5
Richard B. Dulany                         1,875                      0.25
William P. Fitch, III                     7,500                      1
Ralph Fritzsch                            3,750                      0.5
Frederick M. Fry                          1,875                      0.25
Carole Gordon                             7,500                      1
Rudy Haddad                               7,500                      1
Martin E. Hanisch                         1,875                      0.25
Wayne A. Hey                              7,500                      1
Ira Hollander                             5,625                      0.75
Madelyn Holzman                           7,500                      1
Daniel Johnson                            3,750                      0.5
John Johnson                              7,500                      1





<PAGE>



                                  Cash Contribution         Percentage Interest

Alfred A. Kopecky                         7,500                       1
Edward M. Lee                             7,500                       1
Barney Maddox                             3,750                       0.5
David W. McNichols                        5,625                       0.75
Raul Mireles                              7,500                       1
Yondell E. Moore                          3,750                       0.5
Michael Newell                            9,375                       1.25
Dennis Ortiz                              3,750                       0.5
M. Sheldon Polsky                         7,500                       1
John A. Pumphrey                          7,500                       1
William Risk                             18,750                       2.5
Dave Rittenhouse                          3,750                       0.5
Lewis Russell                             7,500                       1
Clifford T. Sarnacki                      7,500                       1
Michael F. Sarosdy                        7,500                       1
Randall Singleton                         9,375                       1.25
Howard Solomon                            9,375                       1.25
C. Ritchie Spence                        13,125                       1.75
Robert G. Stroud                          7,500                       1
Leopoldo Tecauanhuey                      7,500                       1
Addison E. Thurman                        7,500                       1
James B. Tyree                            7,500                       1
Michael Walter                            1,875                       0.25
Gordon R. Welch                           1,875                       0.25
Marshall Wiener                           1,875                       0.25
Donald Willis                             7,500                       1
Sidney Worsham                            1,875                       0.25
Randolph Zuber                            5,625                       0.75
Prostatherapies, Inc.                   241,200                      33.5
                                        -------                     ----
         TOTAL                          737,438                     100%




                                        2


<PAGE>


                       PRIME REFRACTIVE MANAGEMENT, L.L.C.

                                 LOAN AGREEMENT

                       $14,000,000.00 ADVANCING TERM LOAN

                              BANK OF AMERICA, N.A.

                             as Administrative Agent

                                BANKBOSTON, N.A.

                             as Documentation Agent

                                       and

                            THE LENDERS NAMED HEREIN,

                                   as Lenders

                          Dated as of January 31, 2000




                         BANC OF AMERICA SECURITIES LLC

                        as Lead Arranger and Book Manager


<PAGE>



                                 LOAN AGREEMENT

                                       vi


                                TABLE OF CONTENTS


ARTICLE I --  DEFINITIONS...................................................2
         Section 1.1       Amendment and Restatement........................2
         Section 1.2       Definitions......................................2
         Section 1.3       Other Definitional Provisions...................17

ARTICLE II --  ADVANCES....................................................17
         Section 2.1       Commitments.....................................17
         Section 2.2        Notes..........................................18
         Section 2.3       Repayment of Notes..............................18
         Section 2.4       Interest........................................19
         Section 2.5       Borrowing Procedure.............................19
         Section 2.6       Continuations; Conversions......................20
         Section 2.7       Use of Proceeds.................................20
         Section 2.8       Fees............................................20

ARTICLE III --  PAYMENTS...................................................20
         Section 3.1       Method of Payment...............................20
         Section 3.2       Optional Prepayment.............................21
         Section 3.3       Pro Rata Treatment..............................21
         Section 3.4       Non-Receipt of Funds by the
                                 Administrative Agent......................21
         Section 3.5       Withholding Taxes...............................21
         Section 3.6       Withholding Tax Exemption.......................22
         Section 3.7       Computation of Interest.........................22
         Section 3.8       Order of Application............................22

ARTICLE IV --  YIELD PROTECTION AND ILLEGALITY.............................23
         Section 4.1       Additional Costs................................23
         Section 4.2       Limitation on Eurodollar Advances...............24
         Section 4.3       Illegality......................................24
         Section 4.4       Treatment of Eurodollar Advances................25
         Section 4.5       Compensation....................................25
         Section 4.6       Capital Adequacy................................26

ARTICLE V --  SECURITY.....................................................26
         Section 5.1       Collateral......................................26
         Section 5.2       Future Liens. ..................................27
         Section 5.3       Release of Collateral...........................28
         Section 5.4       Setoff..........................................28

ARTICLE VI --  CONDITIONS PRECEDENT........................................28
         Section 6.1       Initial Advance.................................28
         Section 6.2       All Advances....................................30

ARTICLE VII --  REPRESENTATIONS AND WARRANTIES.............................31
         Section 7.1       Existence.......................................31
         Section 7.2       Financial Statements............................31
         Section 7.3       Corporate Action:  No Breach....................32
         Section 7.4       Operation of Business...........................32
         Section 7.5       Litigation and Judgments........................32
         Section 7.6       Rights in Properties; Liens.....................32
         Section 7.7       Enforceability..................................32
         Section 7.8       Approvals.......................................33
         Section 7.9       Debt............................................33
         Section 7.10      Taxes...........................................33
         Section 7.11      Use of Proceeds; Margin Securities..............33
         Section 7.12      ERISA...........................................33
         Section 7.13      Disclosure......................................33
         Section 7.14      Subsidiaries; Partnerships......................34
         Section 7.15      Agreements......................................34
         Section 7.16      Compliance with Legal Requirements;
                                Governmental Authorizations................34
         Section 7.17      Investment Company Act..........................35
         Section 7.18      Public Utility Holding Company Act..............35
         Section 7.19      Environmental Matters...........................35
         Section 7.20      Year 2000 Compliance............................35

ARTICLE VIII --  POSITIVE COVENANTS........................................35
         Section 8.1       Reporting Requirements..........................35
         Section 8.2       Maintenance of Existence; Conduct of Business...38
         Section 8.3       Maintenance of Properties.......................38
         Section 8.4       Taxes and Claims................................38
         Section 8.5       Insurance.......................................39
         Section 8.6       Inspection Rights...............................39
         Section 8.7       Keeping Books and Records.......................39
         Section 8.8       Compliance with Laws............................39
         Section 8.9       Compliance with Agreements......................39
         Section 8.10      Further Assurances..............................39
         Section 8.11      ERISA...........................................40
         Section 8.12      Information Relating to Proposed Acquisitions...40
         Section 8.13      After-Acquired Subsidiaries.....................40
         Section 8.14      Syndication Cooperation.........................40

ARTICLE IX --  NEGATIVE COVENANTS..........................................40
         Section 9.1       Debt............................................40
         Section 9.2       Limitation on Liens.............................41
         Section 9.3       Mergers, Etc....................................42
         Section 9.4       Restricted Payments.............................42
         Section 9.5       Investments.....................................42
         Section 9.6       Limitation on Issuance of Capital Stock.........43
         Section 9.7       Transactions With Affiliates....................43
         Section 9.8       Disposition of Assets.  ........................43
         Section 9.9       Sale and Leaseback..............................43
         Section 9.10      Prepayment of Debt..............................43
         Section 9.11      Nature of Business..............................44
         Section 9.12      Environmental Protection........................44
         Section 9.13      Accounting......................................44
         Section 9.14      Amendment of Partnership
                                and Management Agreements..................44
         Section 9.15      Financial Hedges................................44
         Section 9.16      Capital Expenditures............................44
         Section 9.17      Operating Expenses..............................44
         Section 9.18      Control of Prime Refractive, L.L.C..............45

ARTICLE X --  FINANCIAL COVENANTS..........................................45
         Section 10.1      Senior Funded Debt To EBITDA Ratio..............45
         Section 10.2      Debt Service Coverage Ratio.....................45

ARTICLE XI --  DEFAULT.....................................................45
         Section 11.1      Events of Default...............................45
         Section 11.2      Remedies........................................47
         Section 11.3      Performance by the Administrative Agent.........48

ARTICLE XII --  THE ADMINISTRATIVE AGENT...................................48
         Section 12.1      Appointment, Powers and Immunities..............48
         Section 12.2      Rights of Administrative Agent as a Lender......49
         Section 12.3      Sharing of Payments, Etc........................50
         Section 12.4      Indemnification.................................50
         Section 12.5      Independent Credit Decisions....................51
         Section 12.6      Several Commitments.............................51
         Section 12.7      Successor Administrative Agent..................51
         Section 12.8      Independent Contractor..........................52

ARTICLE XIII --  MISCELLANEOUS.............................................52
         Section 13.1      Expenses........................................52
         Section 13.2      Indemnification.................................52
         Section 13.3      No Duty.........................................53
         Section 13.4      No Fiduciary Relationship.......................53
         Section 13.5      No Waiver; Cumulative Remedies..................53
         Section 13.6      Successors and Assigns..........................53
         Section 13.7      Survival........................................56
         Section 13.8      ENTIRE AGREEMENT................................56
         Section 13.9      Amendments, Etc.................................56
         Section 13.10     Maximum Interest Rate...........................56
         Section 13.11     Notices.........................................57
         Section 13.12     Governing Law...................................57
         Section 13.13     Counterparts....................................57
         Section 13.14     Severability....................................57
         Section 13.15     Headings........................................57
         Section 13.16     Construction....................................57
         Section 13.17     Independence of Covenants.......................57
         Section 13.18     Confidentiality.................................58
         Section 13.19     Waiver of Jury Trial............................58
         Section 13.20     Choice of Forum; Consent to
                                Service of Process and Jurisdiction. ......58
         Section 13.21     Chapter 346.....................................59



<PAGE>








                                INDEX TO EXHIBITS

Exhibit           Description of Exhibit

A                 Advance Request Form
B                 Form of Assignment and Acceptance
C                 Form of Note
D                 Perfection Certificate

E                 Form of Opinion of Counsel for Borrower and Guarantors
F                 Compliance Certificate
G                 Permitted Refractive Acquisition Certificate


                                                 INDEX TO SCHEDULES

Schedule Description of Schedule

1                 Commitments
2                 Guarantors
3                 Partnerships
7.5               Existing Litigation
7.9               Existing Debt
7.14.1            Capitalization of Subsidiaries
7.14.2            Partners
7.15              Agreements
7.16              Governmental Disclosures
7.19              Environmental Matters
9.2               Existing Liens




<PAGE>



                                 LOAN AGREEMENT


                                 LOAN AGREEMENT

         THIS LOAN AGREEMENT (the "Agreement"), dated as of January 31, 2000, is
among PRIME REFRACTIVE MANAGEMENT,  L.L.C., a Delaware limited liability company
("Borrower"),  each of the  lenders or other  lending  institutions  which is or
which may from  time to time  become a  signatory  hereto  or any  successor  or
assignee thereof  (collectively,  the "Lenders" and  individually,  a "Lender"),
BANK OF AMERICA,  N.A. ("Bank of America"),  a national banking association,  as
Administrative  Agent  for  itself  and the  other  Lenders  (in such  capacity,
together with its successors in such capacity, the "Administrative  Agent"), and
BANKBOSTON,   N.A.   ("BankBoston"),   a  national   banking   association,   as
Documentation Agent for itself and the other Lenders (in such capacity, together
with its successors in such capacity, the "Documentation Agent").

                                 R E C I T A L S

         1. Reference is hereby made to that certain Loan Agreement  dated as of
November 28,  1994,  by and between  Prime  Medical  Services,  Inc., a Delaware
corporation ("Prime Medical"),  of which Borrower is a Wholly-Owned  Subsidiary,
the Banks defined therein, and BankBoston (then known as The First National Bank
of Boston),  as Agent for the Banks defined therein,  as amended by that certain
First Amendment to Loan Agreement dated as of August 17, 1995, as amended by the
Amended  and  Restated  Loan  Agreement  dated as of April 26,  1996 among Prime
Medical,  Bank of  America  (then  known as  NationsBank  of  Texas,  N.A.),  as
Documentation Agent,  BankBoston,  as Administrative  Agent, and BankBoston,  as
Syndication  Agent,  as amended by the First  Amendment  to Amended and Restated
Loan Agreement dated as of June 14, 1996 among Prime Medical,  BankBoston,  Bank
of America (then known as NationsBank of Texas, N.A.), and the other banks named
therein,  as further  amended by the Second  Amended and Restated Loan Agreement
dated as of March 31, 1997 among Prime Medical,  BankBoston,  as  Administrative
Agent,  Bank  of  America  (then  known  as  NationsBank  of  Texas,  N.A.),  as
Documentation  Agent,  and NationsBanc  Capital  Markets,  Inc., and the lenders
named  therein,  as amended and waived from time to time, as further  amended by
the Third Amended and Restated Loan  Agreement  dated as of April 20, 1998 among
Prime  Medical,  BankBoston,  as original  Administrative  Agent,  and successor
Documentation Agent, Bank of America (then known as NationsBank of Texas, N.A.),
as original  Documentation  Agent and successor  Administrative  Agent,  and the
lenders named  therein,  as amended and waived from time to time  (collectively,
the "Original Credit Agreement").

         2. The parties hereto desire to  restructure,  modify,  refinance,  and
replace a $14,000,000  portion of the credit  available  under  Original  Credit
Agreement, subject to the terms and conditions set forth in this Agreement.

         NOW  THEREFORE,  in  consideration  of  the  premises  and  the  mutual
covenants herein contained, the parties hereto agree as follows:


<PAGE>


                            ARTICLE I -- DEFINITIONS

         Section 1.1 Amendment and Restatement.  The Obligations (as hereinafter
defined) are in  restructure,  modification,  refinancing,  and replacement of a
portion  of the  credit  available  under  the  Original  Credit  Agreement  and
constitutes and is hereby designated by Borrower as "Designated  Senior Debt" as
defined in the Senior  Subordinated  Indenture,  and is a portion of the "Senior
Credit Facility" under the Senior Subordinated Indenture.

     Section 1.2  Definitions.  As used in this  Agreement,  the following terms
shall have the following meanings:  "Acquisition" means any transaction,  or any
series of related  transactions,  consummated  on or after the date  hereof,  by
which Borrower or Prime Refractive,  L.L.C.  directly or indirectly (a) acquires
all or substantially  all of the assets of any Person,  whether through purchase
of assets, merger, or otherwise, (b) acquires (in one transaction or as the most
recent  transaction in a series of  transactions) at least a majority (in number
of votes) of the securities (or similar  ownership  interests) of any Person, or
(c) acquires (in one  transaction or as the most recent  transaction in a series
of  transactions)  at least a majority  of the general  partnership  or managing
member interests of any Person, or (d) acquires additional  Partnership or other
equity interests in any Subsidiary.

         "Additional Costs" has the meaning specified in Section 4.1.

         "Adjusted EBITDA" means for any Person for any period,  the sum of: (i)
EBITDA,  except  in  the  case  of  any  Target  Company  in  respect  of  which
Consolidated  Earn-Out  Indebtedness  is payable,  EBITDA of such Target Company
shall be increased by the amount, if any, by which the annualized fiscal year to
date EBITDA used in the definition of Consolidated Earn-Out Indebtedness exceeds
the actual EBITDA for the four previous  fiscal quarters of such Person for such
period,  plus  (ii)  without  duplication,  all cash  Distributions  related  to
minority  interests in Partnerships  actually  received by Borrower;  plus (iii)
without  duplication,  on a pro forma  basis the  EBITDA of any  Target  Company
acquired  during  such  period as if it were  acquired  on the first day of such
period.

         "Adjusted  Eurodollar Rate" means,  for any Eurodollar  Advance for any
Interest Period therefor, the rate per annum (rounded upwards, if necessary,  to
the nearest 0.01%) determined by the Administrative Agent to be equal to (a) the
Eurodollar Rate for such Eurodollar  Advance for such Interest Period divided by
(b) 1.00 minus the  Reserve  Requirement  for such  Eurodollar  Advance for such
Interest Period.

     "Administrative  Agent"  means Bank of  America,  N.A.,  and its  permitted
successors  and  assigns  as  "Administrative  Agent"  for  Lenders  under  this
Agreement.

         "Advance"  means each advance of funds by the Lenders or any of them to
Borrower pursuant to Section 2.5(a).

         "Advance Request Form" means a certificate,  in substantially  the form
of Exhibit A, properly completed and signed by Borrower requesting an Advance.


<PAGE>


         "Affiliate" means, as to any Person, any other Person (a) that directly
or indirectly, through one or more intermediaries, Controls or is Controlled by,
or is under common  Control with,  such Person,  (b) that directly or indirectly
beneficially  owns or holds  five  percent  (5%) or more of any  class of voting
stock of such  Person,  or (c) five  percent (5%) or more of the voting stock of
which is  directly  or  indirectly  beneficially  owned or held by the Person in
question;  provided,  however,  in no event  shall the  Agents or any  Lender be
deemed an Affiliate of Borrower or any of its Subsidiaries.

         "After-Acquired Subsidiary" has the meaning specified in Section 8.13.

     "Agents" means the Administrative  Agent, the Documentation  Agent, and the
Lead Arranger. "Agent" means any one of the Agents.

         "Alternate  Base  Rate"  means,  at any time,  the  greater  of (a) the
variable rate of interest  established  from time to time by the  Administrative
Agent as its  "base  rate"  and set by the  Administrative  Agent  as a  general
reference  rate of interest  charged by the  Administrative  Agent,  and (b) the
Federal Funds Rate plus  one-half of one percent  (.5%).  Borrower  acknowledges
that the  Administrative  Agent may,  from time to time,  extend credit to other
borrowers at rates of interest varying from, and having no relationship to, such
general  reference  rate.  Each change in the  Alternate  Base Rate shall become
effective  without prior notice to Borrower  automatically  as of the opening of
business on the date of such change in the Alternate Base Rate.

         "Alternate  Base Rate  Advances"  means  Advances that bear interest at
rates based upon the Alternate Base Rate.

         "Applicable  Lending  Office"  means for each  Lender  and each Type of
Advance,  the lending  office of such Lender (or of an Affiliate of such Lender)
designated for such Type of Advance below its name on the signature pages hereof
or an Assignment and  Acceptance,  or such other office of such Lender (or of an
Affiliate  of such  Lender)  as such  Lender  may from time to time  specify  to
Borrower  and the  Administrative  Agent as the office by which its  Advances of
such Type are to be made and maintained.

         "Applicable  Margin" means the interest  margin over the Alternate Base
Rate or the Adjusted Eurodollar Rate, as the case may be, for Advances under the
Commitment  (a) from the date hereof until the delivery of financial  statements
and a  compliance  certificate  for the period  ending  December  31,  1999,  as
required hereunder, three-eighths of one percent (.375%) for Alternate Base Rate
Advances,  and one and  seven-eighths  of one percent  (1.875%)  for  Eurodollar
Advances; and (b) thereafter,  based on the Total Funded Debt to EBITDA Ratio as
of and for the most recent four (4) quarter  period ending on or before the date
of determination, the margin set forth opposite such ratio below:

========================== =========================== =========================

                                Applicable Margin

       Total Funded               Alternate Base Rate        Applicable Margin
   Debt to EBITDA Ratio                Advances             Eurodollar Advances

- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

Less than 1.5 to 1.0                   0.375%                     1.875%
- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

Greater than or equal
         to 2.75 to 1.0                1.375%                     2.875%
========================== =========================== =========================



<PAGE>


The Total  Funded Debt to EBITDA  Ratio shall be  determined  from the then most
current of either (a) the quarterly or annual  financial  statements and related
compliance certificate delivered pursuant to Section 8.1, or (b) the most recent
Advance  Request Form for a Permitted  Refractive  Acquisition,  calculating any
adjustments to such ratio  necessitated as a result of the Permitted  Refractive
Acquisition  for which such  Advance was made.  The  adjustment,  if any, to the
Applicable Margin shall be effective  commencing on the fifth (5th) Business Day
after delivery of such financial statements (and related compliance certificate)
or the respective date of Advance for a Permitted Refractive Acquisition, as the
case may be. If  Borrower  fails at any time to  furnish  to the  Administrative
Agent  and  the  Lenders  the  financial   statements  and  related   compliance
certificate  as  required to be  delivered  pursuant  to Section  8.1,  then the
maximum  Applicable  Margin  shall  apply  until  such  time as  such  financial
statements and compliance certificates are so delivered.

         "Applicable  Rate"  means:  (a) during any period that an Advance is an
Alternate Base Rate Advance, the Alternate Base Rate plus the Applicable Margin;
and (b) during any period that an Advance is a Eurodollar Advance,  the Adjusted
Eurodollar Rate plus the Applicable Margin.

         "Applicable  Unused  Fee  Percentage"  means  the per  annum  rate with
respect to the unused portion of the  Commitments as follows:  (a) from the date
hereof until delivery of financial  statements and a compliance  certificate for
the period ending December 31,1999, as required  hereunder,  three-eights of one
percent  (.375%);  and (b) thereafter,  based on the Total Funded Debt to EBITDA
Ratio as of and for the most recent four (4) quarter  period ending on or before
the date of determination, the percentage set forth opposite such ratio below:

====================================================== =========================

                       Total Funded Applicable Unused Fee

          Debt to EBITDA Ratio                         Percentage

- ------------------------------------------------------ -------------------------
- ------------------------------------------------------ -------------------------

          Less than 1.5 to 1.0                                            .375%
- ------------------------------------------------------ -------------------------
- ------------------------------------------------------ -------------------------

          Greater than or equal to 1.5 to 1.0                             .500%
====================================================== =========================

The Applicable  Unused Fee Percentage  shall be adjusted,  if necessary,  at the
same time as adjustments to the Applicable Margin. If Borrower fails at any time
to furnish to the Administrative  Agent and the Lenders the financial statements
and related  compliance  certificate  as required  to be  delivered  pursuant to
Section 8.1, then the maximum Applicable Unused Fee Percentage shall apply until
such  time as such  financial  statements  and  compliance  certificates  are so
delivered.

         "Assignee" has the meaning specified in Section 13.6.

         "Assigning Lender" has the meaning specified in Section 13.6.

         "Assignment and Acceptance" means an assignment and acceptance  entered
into by an Assigning Lender and its Assignee and accepted by the  Administrative
Agent pursuant to Section 13.6, in substantially the form of Exhibit B.

     "Bank of America" means Bank of America,  N.A. and its permitted successors
and assigns.

     "BankBoston"  means  BankBoston,  N.A.  and its  permitted  successors  and
assigns.


<PAGE>


         "Basle  Accord" means the proposals for  risk-based  capital  framework
described  by  the  Basle  Committee  on  Banking  Regulations  and  Supervisory
Practices  in  its  paper   entitled   "International   Convergence  of  Capital
Measurement and Capital  Standards" dated July,  1988, as amended,  supplemented
and  otherwise  modified  and in effect  from time to time,  or any  replacement
thereof.

         "Borrower Security Agreement" means (a) the Borrower Security Agreement
dated as of the date  hereof,  executed by  Borrower in favor of  Administrative
Agent for the benefit of the Lenders, as the same may be amended,  supplemented,
or modified from time to time.

         "Business Day" means (a) any day on which the  Administrative  Agent is
open for regular  business,  and (b) with respect to all  borrowings,  payments,
Conversions,  Continuations,  Interest  Periods,  and notices in connection with
Eurodollar  Advances,  any day which is a Business  Day  described in clause (a)
above and which is also a day on which  dealings in Dollar  deposits are carried
out in the London interbank market.

         "Capital  Expenditure"  means any  expenditure by a Person for an asset
which  will be used in a year or  years  subsequent  to the  year in  which  the
expenditure  is made  and  which  asset is  properly  classifiable  in  relevant
financial  statements  of such Person as property,  equipment  or  improvements,
fixed assets, or a similar type of capitalized asset in accordance with GAAP.

         "Capital Lease Obligations" means, as to any Person, the obligations of
such Person to pay rent or other  amounts  under a lease of (or other  agreement
conveying the right to use) real and/or personal property, which obligations are
required to be  classified  and  accounted  for as a capital  lease on a balance
sheet of such Person under GAAP. For purposes of this  Agreement,  the amount of
such Capital Lease  Obligations  shall be the  capitalized  amount  thereof,  as
determined in accordance with GAAP.

         "Change  in  Control"  means any of the  following  has  occurred:  (i)
Borrower  ceases to own legally and  beneficially at least 51% of the membership
interests in Prime Refractive,  LLC or ceases to Control Prime Refractive,  LLC,
(ii) Prime RVC ceases to own  legally  and  beneficially  100% of the issued and
outstanding equity securities of Borrower,  (iii) PMOI ceases to own legally and
beneficially  100% of the issued  and  outstanding  stock of Prime RVC,  or (iv)
Prime Medical Services,  Inc. ceases to own legally and beneficially 100% of the
issued and outstanding stock of PMOI.

         "Code" means the Internal  Revenue  Code of 1986,  as amended,  and the
regulations promulgated and rulings issued thereunder.

         "Collateral" has the meaning specified in Section 5.1.

         "Collateral  Documents"  means the  Borrower  Security  Agreement,  the
Guarantor Security Agreements,  the Pledge Agreements, and all other collateral,
security,  lien  creating  agreements  executed or  delivered  pursuant to or in
connection with this Agreement, as the same may be amended,  modified,  renewed,
or supplemented from time to time.


<PAGE>


         "Commitment" means, as to each Lender as of any date, the obligation of
such Lender on such date to make  Advances  hereunder in an aggregate  principal
amount at any time  outstanding  up to but not  exceeding  the  amount  shown on
Schedule 1 as its  Commitment,  as the same may be reduced  pursuant  to Section
2.1(b) or terminated  pursuant to Section 2.1(b) or Section 11.2 and as the same
may be increased or decreased from time to time by further  assignment  pursuant
to Section 13.6.  "Commitments"  means the  Commitments of all of the Lenders in
the original aggregate amount of $14,000,000.00.

         "Companies" means Borrower and its Subsidiaries.

         "Confidential  Information"  means any and all information  relating to
the Companies,  including,  without limitation,  information relating to each of
the Company's financial condition, business plans, management, earnings, assets,
liabilities,   contracts,   processes,   products,   research  and   development
activities, intellectual property, services, customers, suppliers, marketing and
sales.  In addition,  Confidential  Information  shall include any and all other
information  marked  or  identified  in  writing  by  any of  the  Companies  as
"Confidential"  or  "Confidential  Information"  and  provided  by  each  of the
Companies or its representatives to any of the Lenders or the Agents or obtained
by the  Lenders or the  Agents  after an  inspection  pursuant  to Section  8.6.
Notwithstanding the foregoing, "Confidential Information" shall not include:

                  (i) any  information  known to an  Agent or a Lender  prior to
         disclosure  by  any  of  the  Companies  or  its  representatives,   as
         documented prior to such disclosure in such Agent's or Lender's written
         records;

                  (ii) any information  which an Agent or a Lender  demonstrates
         became available to it on a non-confidential basis from a source (other
         than  any of the  Companies)  who is  not  bound  by a  confidentiality
         agreement with, or any other contractual, legal or fiduciary obligation
         of  confidentiality  to, any of the  Companies  or any other party with
         respect to such information;

                  (iii) any information which an Agent or a Lender  demonstrates
         is or becomes generally  available to the public other than as a result
         of a disclosure by it in breach of Section 13.18; and

                  (iv) any information  which an Agent or a Lender  demonstrates
         was  conceived of or developed  by it or any of its  employees  without
         access  or  reference,  directly  or  indirectly,  to the  Confidential
         Information.

         "Consolidated  Earn-Out  Indebtedness"  means as to any Person,  at any
time, in connection with each  applicable  Permitted  Refractive  Acquisition in
which an earn-out payment or other post-closing payment or payments is or may be
due pursuant to the applicable purchase or acquisition agreement,  the projected
aggregate  amount of such  earn-out or  post-closing  payments  that would be or
become due based upon all events or  circumstances  that have occurred as of any
date of determination, regardless of whether any such payments are then actually
payable under the terms of the  applicable  purchase or  acquisition  agreement;
provided that to the extent any such payments are based on net income, revenues,
EBITDA or similar  financial  performance  criteria of any Target  Company for a
defined   post-closing  period  or  periods,  the  actual  applicable  financial
performance  during the  applicable  period to date shall be  utilized in making
such projection.  Borrower shall submit the calculation of Consolidated Earn-Out
Indebtedness with respect to each applicable Permitted  Refractive  Acquisition,
together with each compliance  certificate delivered pursuant to Section 8.1(d),
together  with any  applicable  supporting  documentation,  all of which must be
satisfactory to Administrative Agent.

         "Consolidated  Net Income"  means,  for any Person for any period,  the
amount which, in conformity with GAAP,  would be shown on a consolidated  income
statement of such Person as net income for such period,  after  deduction of any
minority interests.


<PAGE>


         "Continue,"  "Continuation," and "Continued" refers to the continuation
pursuant to Section 2.6 of a Eurodollar  Advance from one Interest Period to the
next Interest Period.

         "Control" means the possession, directly or indirectly, of the power to
direct or cause the direction of the management or policies of a Person, whether
through the ownership of voting  securities  or other  ownership  interests,  by
contract or otherwise.  "Controlling" and "Controlled" have meanings correlative
thereto.

         "Conversion" and "Converted" refers to a conversion pursuant to Section
2.6 of one Type of Advance into another Type of Advance.

         "Debt"  means as to any  Person at any time  (without  duplication  and
without duplication among the Companies): (a) all obligations of such Person for
borrowed money;  (b) all obligations of such Person  evidenced by bonds,  notes,
debentures,  or  other  similar  instruments,   including,  without  limitation,
Subordinated  Debt;  (c) all  obligations  of such  Person  to pay the  deferred
purchase  price  of  property  or  services,   including,   without  limitation,
Consolidated Earn-Out Indebtedness, except trade accounts payable of such Person
arising in the  ordinary  course of business  that are not past due by more than
ninety (90) days;  (d) all Capital  Lease  Obligations  of such Person;  (e) all
indebtedness  or other  obligations  of others of the  types  described  in this
definition, if Guaranteed by such Person or for which such Person is liable as a
partner in any  partnership  or joint  venturer  in any joint  venture;  (f) all
obligations secured by a Lien existing on property owned by such Person, whether
or not the  obligations  secured thereby have been assumed by such Person or are
non-recourse to the credit of such Person; (g) all reimbursement  obligations of
such Person  (whether  contingent or otherwise) in respect of letters of credit,
banker's  acceptances,  surety  or other  bonds  and  similar  instruments;  (h)
obligations under any Financial Hedge; and (i) all liabilities of such Person in
respect of unfunded vested benefits under any Plan; provided,  however, that the
term  Debt  shall  not  include  endorsements  of  instruments  for  deposit  or
collection in the ordinary course of business.

         "Debt Service Coverage Ratio" means, as to the Companies  (including on
a pro forma basis any Company acquired in any Permitted  Refractive  Acquisition
for each of the  components of and for the entire period of  calculation of Debt
Service  Coverage  Ratio)  for any  period,  the  ratio  of (a) the sum of:  (i)
Adjusted  EBITDA for such  period,  minus (ii) the  aggregate  amount of capital
expenditures made during such period, minus (iii) all cash tax payments, divided
by (b) the sum of: (w) all cash interest  payments payable during such period in
respect  of all  Debt of the  Companies  (without  deduction  for  any  minority
interests),  plus (x) 1/7 of the outstanding principal amount of the Loans as of
any  date of  determination,  plus  (y)  1/7 of the  then  applicable  aggregate
Earn-Out  Indebtedness,  plus (z) any regularly  scheduled principal payments on
Debt  (including   Subordinated  Debt,  but  excluding   Consolidated   Earn-Out
Indebtedness)  all as determined on a rolling four (4) quarter and  consolidated
basis in accordance with GAAP.

         "Default"  means an Event of Default or the  occurrence  of an event or
condition  which  with the  giving of notice or the lapse of time or both  would
become an Event of Default.

         "Default  Rate" means the lesser of (a) the Maximum  Rate,  and (b) the
sum of the  Alternate  Base Rate in effect  from day to day plus the  Applicable
Margin plus two percent (2%).

         "Defaulting  Lender"  means any Lender that in  Administrative  Agent's
reasonable  judgment  has  defaulted  on  any  of  its  obligations  under  this
Agreement.


<PAGE>


         "Distribution"  for any Person means, with respect to any shares of any
capital  stock,  general  or  limited  partnership  interests,  or other  equity
securities issued by such Person, (a) the retirement,  redemption,  purchase, or
other  acquisition  for value of any such  securities,  (b) the  declaration  or
payment of any  dividend,  distribution,  income,  or other  amount,  on or with
respect to any such  securities or interests,  and (c) any other payment by such
Person with respect to such securities or interests.

         "Documentation  Agent"  means  BankBoston,   N.A.,  and  its  permitted
successors  and  assigns  as  "Documentation   Agent"  for  Lenders  under  this
Agreement.

         "Dollars" and "$" mean lawful money of the United States of America.

         "EBITDA" means,  for any Person for any period:  (a)  Consolidated  Net
Income  of such  Person  for such  period,  determined  after  deduction  of any
minority interests,  plus (b) all amounts deducted therefrom during such period,
in conformity with GAAP, for interest, taxes, depreciation and amortization.

         "Eligible  Assignee" means (i) a Lender; (ii) an Affiliate of a Lender;
or (iii) any other Person approved by the  Administrative  Agent (which approval
shall not be  unreasonably  withheld  or delayed by  Administrative  Agent) and,
unless  an Event of  Default  has  occurred  and is  continuing  at the time any
assignment is effected in accordance with Section 13.6, Borrower,  such approval
not to be  unreasonably  withheld or delayed by Borrower and such approval to be
deemed given by Borrower if no objection is received by the assigning Lender and
the Administrative Agent from Borrower within two (2) Business Days after notice
of such  proposed  assignment  has been  provided  by the  assigning  Lender  to
Borrower;  provided, however, that neither Borrower nor an Affiliate of Borrower
shall qualify as an Eligible Assignee.

     "Environmental  Laws"  means any and all  federal,  state,  and local laws,
regulations,  and requirements pertaining to health, safety, or the environment,
including,   without  limitation,  the  Comprehensive   Environmental  Response,
Compensation and Liability Act of 1980, 42 U.S.C.ss.  9601 et seq., the Resource
Conservation  and  Recovery  Act  of  1976,  42  U.S.C.ss.  6901  et  seq.,  the
Occupational Safety and Health Act, 29 U.S.C.ss. 651 et seq., the Clean Air Act,
42 U.S.C.ss.7401 et seq., the Clean Water Act, 33 U.S.C.ss.1251 et seq., and the
Toxic  Substances   Control  Act,  15  U.S.C.ss.2601  et  seq.,  as  such  laws,
regulations, and requirements may be amended or supplemented from time to time.

         "Environmental  Liabilities"  means, as to any Person, all liabilities,
obligations,  responsibilities,  Remedial  Actions,  losses,  damages,  punitive
damages,  consequential damages, treble damages, costs, and expenses (including,
without limitation,  all reasonable fees, disbursements and expenses of counsel,
expert and consulting fees and costs of investigation and feasibility  studies),
fines, penalties,  sanctions,  and interest incurred as a result of any claim or
demand,  by any Person,  whether  based in  contract,  tort,  implied or express
warranty,   strict   liability,   criminal  or  civil  statute,   including  any
Environmental Law, permit, order or agreement with any Governmental Authority or
other Person,  arising from  environmental,  health or safety  conditions or the
Release or  threatened  Release of a Hazardous  Material  into the  environment,
resulting  from the past,  present,  or future  operations of such Person or its
Affiliates.

         "ERISA" means the Employee  Retirement  Income Security Act of 1974, as
amended from time to time,  and the  regulations  and published  interpretations
thereunder.


<PAGE>


         "ERISA Affiliate" means any corporation or trade or business which is a
member of the same  controlled  group of  corporations  (within  the  meaning of
Section 414(b) of the Code) as Borrower or is under common  control  (within the
meaning of Section 414(c) of the Code) with Borrower.

         "Eurodollar  Advances"  means  Advances the interest rates on which are
determined on the basis of the rates  referred to in the definition of "Adjusted
Eurodollar Rate" in this Section 1.1.

         "Eurodollar  Rate" means,  for any Eurodollar  Advance for any Interest
Period  therefor,  the rate per annum  (rounded  upwards,  if necessary,  to the
nearest 1/100 of 1%) appearing on Telerate Page 3750 (or any successor  page) as
the London interbank offered rate for deposits in Dollars at approximately 11:00
a.m.  (London  time) two Business  Days prior to the first day of such  Interest
Period for a term  comparable  to such Interest  Period.  If for any reason such
rate is not available, the term "Eurodollar Rate" shall mean, for any Eurodollar
Advance for any Interest Period therefor,  the rate per annum (rounded  upwards,
if necessary,  to the nearest 1/100 of 1%) appearing on Reuters Screen LIBO Page
as the London  interbank  offered rate for deposits in Dollars at  approximately
11:00  a.m.  (London  time)  two  Business  Days  prior to the first day of such
Interest  Period  for a term  comparable  to  such  Interest  Period,  provided,
however,  if more than one rate is  specified on Reuters  Screen LIBO Page,  the
applicable rate shall be the arithmetic mean of all such rates.

         "Event of Default" has the meaning specified in Section 11.1.

         "Federal  Funds Rate" means,  for any day, the rate per annum  (rounded
upwards,  if necessary,  to the nearest 0.01%) equal to the weighted  average of
the rates on overnight  Federal funds  transactions  with members of the Federal
Reserve  System  arranged by Federal  funds brokers on such day, as published by
the Federal  Reserve Bank of New York on the Business Day next  succeeding  such
day, provided that (a) if the day for which such rate is to be determined is not
a Business  Day, the Federal  Funds Rate for such day shall be such rate on such
transactions  on the next  preceding  Business  Day as so  published on the next
succeeding  Business  Day, and (b) if such rate is not so published on such next
succeeding Business Day, the Federal Funds Rate for any day shall be the average
rate charged to the  Administrative  Agent on such day on such  transactions  as
determined by the Administrative Agent.

         "Financial Hedge" means either (a) a swap, collar, floor, cap, or other
contract  which is intended to reduce or eliminate the risk of  fluctuations  in
interest rates, or (b) a foreign exchange,  currency hedging, commodity hedging,
or other  contract  which is intended to reduce or eliminate  the market risk of
holding  currency or a commodity  in either the cash or futures  markets,  which
Financial  Hedge  under  either  clause  (a) or clause  (b) is  entered  into by
Borrower with any Lender or an Affiliate of any Lender.

         "GAAP" means generally  accepted  accounting  principles,  applied on a
consistent basis, as set forth in Opinions of the Accounting Principles Board of
the American  Institute of Certified Public  Accountants and/or in statements of
the Financial Accounting Standards Board and/or their respective  successors and
which are applicable in the circumstances as of the date in question. Accounting
principles are applied on a "consistent  basis" when the  accounting  principles
applied in a current  period are  comparable  in all material  respects to those
accounting principles applied in a preceding period, except for changes required
by GAAP.  In the event of a change in GAAP,  Administrative  Agent and  Borrower
will  thereafter  negotiate  in good  faith  to  revise  any  covenants  of this
Agreement affected thereby in order to make such covenants  consistent with GAAP
then in effect.


<PAGE>


         "Governmental  Authority" means any nation or government,  any state or
political subdivision thereof and any entity exercising executive,  legislative,
judicial,   regulatory,   or  administrative   functions  of  or  pertaining  to
government.

         "Governmental Authorization" shall mean any approval, consent, license,
permit, waiver, or other authorization issued, granted, given, or otherwise made
available by or under the authority of any Governmental Authority or pursuant to
any Legal Requirement.

         "Guarantee"  by  any  Person  means  any   obligation,   contingent  or
otherwise,  of such Person directly or indirectly guaranteeing any Debt or other
obligation  of any other  Person and,  without  limiting the  generality  of the
foregoing, any obligation,  direct or indirect, contingent or otherwise, of such
Person (a) to purchase or pay (or  advance or supply  funds for the  purchase or
payment  of)  such  Debt or other  obligation  (whether  arising  by  virtue  of
partnership arrangements,  by agreement to keep-well, to purchase assets, goods,
securities  or services,  to  take-or-pay,  or to maintain  financial  statement
conditions or otherwise), or (b) entered into for the purpose of assuring in any
other manner the obligee of such Debt or other obligation of the payment thereof
or to protect the obligee against loss in respect thereof (in whole or in part),
provided that the term "Guarantee" shall not include endorsements for collection
or deposit in the ordinary course of business.  The term  "Guarantee"  used as a
verb has a corresponding meaning.

         "Guaranties" means,  collectively,  (a) the Guaranty  Agreements,  each
dated  as of the  date  hereof,  executed  by the  Guarantors  in  favor  of the
Administrative  Agent for the benefit of the Lenders, and shall also include any
other guaranty  agreement  heretofore or hereafter from time to time executed by
any  Guarantor  and  delivered  to the  Administrative  Agent for the benefit of
Lenders,  as the same may be amended,  restated,  renewed,  and substituted from
time to time. "Guaranty" means any one of the Guaranties.

         "Guarantors" means, collectively, Prime Medical, all "Guarantors" under
the Prime Facility, Prime Refractive,  LLC, and all Wholly-Owned Subsidiaries of
Borrower,  now owned or hereafter  acquired or formed, and "Guarantor" means any
one of the Guarantors.

         "Guarantor Security Agreements" means (a) the Security Agreements, each
dated  as  of  the  date  hereof,   executed  by  the  Guarantors  in  favor  of
Administrative Agent for the benefit of the Lenders , (b) the Security Agreement
dated as of the date  hereof,  executed  by LASIK  Investors,  LLC,  in favor of
Administrative Agent for the benefit of the Lenders, relating to its interest in
Prime Refractive,  LLC, and (c) shall also include any other security agreements
heretofore  or hereafter  from time to time  executed by any  Guarantor or LASIK
Investors,  LLC and  delivered  to the  Administrative  Agent for the benefit of
Lenders,  as amended,  restated,  renewed,  and  substituted  from time to time.
"Guarantor   Security  Agreement"  means  any  one  of  the  Guarantor  Security
Agreements.

         "Hazardous Material" means any substance,  product,  waste,  pollutant,
material,  chemical,  contaminant,  constituent,  or other  material which is or
becomes listed,  regulated, or addressed under any Environmental Law, including,
without limitation, asbestos, petroleum, and polychlorinated biphenyls.


<PAGE>


         "Interest Period" means, with respect to any Eurodollar  Advance,  each
period  commencing on the date such Advance is made or Converted from an Advance
of another Type or, in the case of each subsequent,  successive  Interest Period
applicable to a Eurodollar Advance,  the last day of the next preceding Interest
Period with respect to such Advance, and ending on the numerically corresponding
day in the first (1st),  second (2nd), third (3rd) or sixth (6th) calendar month
thereafter,  as Borrower  may select as  provided in Section 2.5 or 2.6,  except
that each such  Interest  Period which  commences on the last  Business Day of a
calendar  month (or on any day for which there is no  numerically  corresponding
day in the appropriate subsequent calendar month) shall end on the last Business
Day of the appropriate subsequent calendar month. Notwithstanding the foregoing:
(a) each  Interest  Period  which  would  otherwise  end on a day which is not a
Business  Day  shall  end on the  next  succeeding  Business  Day  (or,  if such
succeeding Business Day falls in the next succeeding calendar month, on the next
preceding  Business Day); (b) any Interest Period which would  otherwise  extend
beyond the Termination Date shall end on the Termination  Date; (c) no more than
four (4)  Interest  Periods  shall be in  effect  at the same  time;  and (d) no
Interest  Period  shall have a duration  of less than one (1) month and,  if any
Interest Period would otherwise be a shorter period,  such Advances shall not be
available hereunder.

         "Lead Arranger" means Bank of America Securities LLC.

         "Legal Requirement" shall mean any federal,  state,  local,  municipal,
foreign,   international,   multinational,   or  other   administrative   order,
constitution,  law, ordinance, principle of common law, regulation,  statute, or
treaty as in effect on the date hereof.

         "Lenders"   mean,   on  any  date  of   determination,   the  financial
institutions named on Schedule 2.1 (as the same may be amended from time to time
by  Administrative  Agent to reflect the  assignments  made in  accordance  with
Section 13.6(b) of this  Agreement),  and subject to the terms and conditions of
this  Agreement,  and  their  respective  successors  and  assigns  (but not any
Participant  who is not  otherwise a party to this  Agreement);  provided  that,
solely for purposes of any Collateral  Documents and Section 12, "Lenders" shall
also  include any Lender or  Affiliate of a Lender who is a party to a Financial
Hedge with Borrower and their  respective  successors  and assigns (for purposes
hereof,  each Lender shall be deemed to have entered into this Agreement for and
on behalf of any  Affiliate  now or  hereafter  party to a Financial  Hedge with
Borrower).

         "Lien" means any lien, mortgage, security interest, tax lien, financing
statement, pledge, charge, hypothecation,  assignment,  preference, priority, or
other  encumbrance  of  any  kind  or  nature  whatsoever  (including,   without
limitation, any conditional sale or title retention agreement),  whether arising
by contract, operation of law, or otherwise.

         "Loan" means all Advances with respect to the Commitment,  evidenced by
the Notes.

         "Loan Documents" means this Agreement,  the Notes, the Guaranties,  the
Borrower  Security  Agreement,  the Guarantor  Security  Agreements,  the Pledge
Agreements, any Financial Hedge documents, and all other instruments, documents,
and  agreements  executed and delivered  pursuant to or in connection  with this
Agreement,  as such  instruments,  documents,  and  agreements  may be  amended,
modified, renewed, extended, or supplemented from time to time.

         "Maximum Rate" means,  at any time and with respect to any Lender,  the
maximum  rate of  interest  under  applicable  law that such  Lender  may charge
Borrower.  The  Maximum  Rate shall be  calculated  in a manner  that takes into
account  any and all fees,  payments,  and other  charges in respect of the Loan
Documents  that  constitute  interest under  applicable  law. Each change in any
interest rate provided for herein based upon the Maximum Rate  resulting  from a
change in the Maximum Rate shall take effect  without  notice to Borrower at the
time of such change in the Maximum Rate.


<PAGE>


         "Multiemployer  Plan" means a multiemployer  plan as defined in Section
3(37) of ERISA to which  contributions  have been made by  Borrower or any ERISA
Affiliate of Borrower and which is covered by Title IV of ERISA.

         "Note"  means  an  advancing  term  loan  note  executed  by  Borrower,
substantially  in the form of  Exhibit C,  payable  to each  Lender in an amount
equal to such  Lender's  Commitment,  as the same may be amended,  supplemented,
modified or restated from time to time, evidencing the obligation of Borrower to
repay the Loan, and all renewals,  modifications and extensions thereof. "Notes"
means all of the Notes of the Lenders.

         "Obligated  Party"  means any  Person  who is or  becomes  party to any
agreement that  guarantees or secures payment and performance of the Obligations
or any part thereof.

         "Obligations" means all obligations,  indebtedness,  and liabilities of
Borrower to the Agents and the Lenders,  or any of them, arising pursuant to any
of the Loan  Documents,  now  existing or  hereafter  arising,  whether  direct,
indirect,  related,  unrelated,  fixed,  contingent,  liquidated,  unliquidated,
joint,  several, or joint and several, and all interest accruing thereon and all
attorneys'  fees and other  expenses  incurred in the  enforcement or collection
thereof;  provided that, all references to the  "Obligations"  in the Collateral
Documents, and in Section 12, shall, in addition to the foregoing,  also include
all present  and future  indebtedness,  liabilities,  and  obligations  (and all
renewals and  extensions  thereof or any part thereof) now or hereafter  owed to
any Lender or any Affiliate of a Lender  arising from, by virtue of, or pursuant
to any Financial Hedge entered into by any Company.

         "Partnerships"  means the partnerships and limited liability  companies
in which  Borrower or any  Subsidiary  now owns or  hereafter  acquires  general
and/or limited partnership interests or membership interests, including, without
limitation,   the   partnerships   and  other  Persons  listed  on  Schedule  3.
"Partnership" means any one of the Partnerships,  and shall also include any non
Wholly-Owned Subsidiaries of Borrower.

         "Payment  Date" means (a) with respect to Alternate  Base Rate Advances
and the commitment fees payable  pursuant to Section  2.8(a),  the last Business
Day of each April, July, October, and January,  commencing January 31, 2000, and
(b) with respect to Eurodollar Advances, the last day of the respective Interest
Period therefor,  provided that if any Interest Period is greater than three (3)
months,  then accrued interest shall also be due and payable on the date that is
three (3) months after the commencement of such Interest Period.

         "PBGC" means the Pension  Benefit  Guaranty  Corporation  or any entity
succeeding to all or any of its functions under ERISA.

         "Permitted  Refractive  Acquisition"  means an acquisition by Borrower,
any Guarantor,  or Prime Refractive,  L.L.C.,  with respect to which each of the
following conditions shall have been satisfied:

                  (a) the  acquisition  by  Borrower,  any  Guarantor,  or Prime
         Refractive, LLC is of a business, assets, or Person (as applicable, the
         "Target  Company ") which is engaged in the  businesses  of  correcting
         refractive error of the eye which are  substantially  the same as those
         which are  conducted by Borrower or any Company on the date hereof,  or
         any other business reasonably related thereto;


<PAGE>


                  (b)  as  of  the   closing   of  such   Permitted   Refractive
         Acquisition,  the Permitted Refractive Acquisition has been approved by
         the board of directors or other applicable governing body of the Target
         Company and the Person from which the Target Company is to be acquired;

               (c)  prior  to  the   closing   of  such   Permitted   Refractive
          Acquisition,  the Target  Company and the Person from which the Target
          Company is to be acquired must be Solvent;

                  (d)  as  of  the   closing   of  such   Permitted   Refractive
         Acquisition,   after  giving  effect  to  such   Permitted   Refractive
         Acquisition,  Borrower, the Guarantor, or Prime Refractive LLC, that is
         the  acquiring  party,  as the case  may be,  must be  Solvent  and the
         Companies, on a consolidated basis, must be Solvent;

                  (e)  as  of  the   closing   of  such   Permitted   Refractive
         Acquisition,   after  giving  effect  to  such   Permitted   Refractive
         Acquisition,  no Default shall exist or occur as a result of, and after
         giving effect to, such Permitted Refractive Acquisition;

                  (f)  the  aggregate   purchase  price  with  respect  to  such
         Permitted  Refractive  Acquisition does not exceed six (6) times EBITDA
         of  the  Target  Company,  subject  to  adjustments  acceptable  to the
         Administrative  Agent,  for the four (4) fiscal  quarters ending on the
         most recently  ended fiscal period prior to the date of such  Permitted
         Refractive Acquisition;

               (g)  the  aggregate  nonstock  consideration  for  any  Permitted
          Refractive Acquisition (including,  without limitation,  any financing
          of interests  acquired by LASIK  Investors,  L.L.C.  and  Consolidated
          Earn-Out Indebtedness reasonably estimated by Administrative Agent and
          Borrower) does not exceed $10,000,000.00;

                  (h) not less than 15 Business Days prior to the closing of any
         Permitted Refractive  Acquisition,  the Administrative Agent shall have
         received pro forma  financial  statements  of the  Companies (as if the
         business,  assets or Person  acquired had been acquired since the first
         (1st) day of the period for which such pro forma  financial  statements
         are delivered and had been managed and conducted in accordance with the
         Borrower's  standard business  practices) for the prior four (4) fiscal
         quarters of Borrower and the Companies;

               (i) if the Target Company is to be an After-Acquired  Subsidiary,
          then Borrower  shall have complied with the terms and  conditions  set
          forth in Section 8.13;

                  (j) review by a third party  acceptable to the  Administrative
         Agent of Borrower's due diligence  process and procedures as related to
         Permitted Refractive  Acquisitions,  acceptable to Administrative Agent
         and Lenders;

                  (k) with respect to any Permitted Refractive Acquisition where
         the aggregate nonstock consideration is $10,000,000 or less (including,
         without  limitation,  any  financing  of  interests  acquired  by LASIK
         Investors,  L.L.C. and Consolidated  Earn-Out  Indebtedness  reasonably
         estimated by  Administrative  Agent and  Borrower),  the Target Company
         has, at a minimum,  provided company prepared financial  statements for
         the immediately  preceding four fiscal quarters  prepared in accordance
         with the due diligence procedures approved in (j) above;


<PAGE>


               (l) the Target Company or other  business  segment being acquired
          must have positive proforma trailing twelve month EBITDA;

               (m) the capital and  ownership  structure  of the Target  Company
          (after giving effect to the Permitted Refractive Acquisition) shall be
          satisfactory to the Administrative Agent;

                  (n) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Permitted  Refractive  Acquisition,  which could have  reasonably  been
         expected to have a material adverse effect on the Target Company or the
         Borrower;

                  (o) receipt of all governmental,  shareholder, and third party
         consents and approvals  necessary or desirable in  connection  with the
         acquisition  of the Target  Company and all  transactions  contemplated
         thereby;

                  (p) the Administrative  Agent has received a certificate dated
         on  or   immediately   prior  to  the  date  of  Permitted   Refractive
         Acquisition,  executed by the President or a Vice President of Borrower
         confirming  that all  representations  and  warranties set forth in the
         Loan Documents continue to be true and correct in all material respects
         immediately   prior  to  and  after  giving  effect  to  the  Permitted
         Refractive  Acquisition and the transactions  contemplated thereby, and
         setting  forth  the   calculations   supporting   compliance  with  the
         limitations prescribed herein; and

               (q) Borrower or Prime Refractive, L.L.C. must own at least 51% of
          the equity or membership  interests in and Control the Target  Company
          upon completion of the Permitted Refractive Acquisition.

         "Person"   means   any   individual,   corporation,   business   trust,
association,  company,  partnership,  joint venture,  Governmental Authority, or
other entity.

         "Plan"  means  any  employee  benefit  or  other  plan  established  or
maintained  by Borrower or any ERISA  Affiliate of Borrower and which is covered
by Title IV of ERISA.

         "Pledge  Agreements" means (a) the Pledge Agreements,  each dated as of
the date hereof, executed by Borrower and each Subsidiary of Borrower that owned
general and/or limited partnership interests in the Partnerships in favor of the
Administrative  Agent,  for the  benefit  of the  Lenders,  as the  same  may be
amended,  supplemented or modified from time to time.  "Pledge  Agreement" means
any one of the Pledge Agreements.

         "Pledgors"  means each of the  pledgors  of  partnership  interests  or
Assigned Rights (as defined in the applicable  Pledge  Agreement)  pursuant to a
Pledge Agreement. "Pledgor" means any one of the Pledgors.

               "PMOI"   means  Prime   Medical   Operating,   Inc.,  a  Delaware
          corporation, and its permitted successors and assigns.

               "Prime  Agent"  means Bank of America,  N.A.,  as  Administrative
          Agent  under the  Prime  Facility  and its  permitted  successors  and
          assigns.

         "Prime Companies" shall mean the "Companies" under the Prime Facility.


<PAGE>


         "Prime  Facility" means the $86,000,000  Revolving Credit Loan to Prime
Medical  pursuant to the Fourth Amended and Restated Loan Agreement  dated as of
the date hereof among Prime Medical,  Bank of America,  N.A., as  Administrative
Agent, BankBoston,  N.A., as Documentation Agent, and the lenders named therein,
as amended, modified, renewed, or restated from time to time.

         "Prime Medical" is defined in the Recitals,  and includes its permitted
successors and assigns.

               "Prime RVC" means Prime RVC,  Inc., a Delaware  corporation,  and
          its permitted successors and assigns.

         "Principal  Office"  means  the  office  of the  Administrative  Agent,
presently located at 901 Main Street, 7th Floor, Dallas, Texas 75202.

         "Prohibited Transaction" means any transaction set forth in Section 406
of ERISA or Section 4975 of the Code.

         "Regulation  D" means  Regulation  D of the Board of  Governors  of the
Federal Reserve System as the same may be amended or  supplemented  from time to
time.

         "Regulatory Change" means, with respect to any Lender, any change after
the date of this Agreement in United States  federal,  state, or foreign laws or
regulations  (including  Regulation D) or the adoption or making after such date
of any  interpretations,  directives,  or requests  applying to a class of banks
including such Lender of or under any United States  federal,  state, or foreign
laws or  regulations  (whether  or not  having the force of law) by any court or
governmental  or  monetary   authority   charged  with  the   interpretation  or
administration thereof.

         "Release"  means,  as to any  Person,  any  release,  spill,  emission,
leaking,  pumping,  injection,  deposit,  disposal,  disbursement,  leaching, or
migration of Hazardous  Materials into the indoor or outdoor environment or into
or out of property  owned by such Person,  including,  without  limitation,  the
movement of Hazardous  Materials  through or in the air,  soil,  surface  water,
ground water, or property.

         "Remedial  Action" means all actions  required to (a) clean up, remove,
treat,  or  otherwise  address  Hazardous  Materials  in the  indoor or  outdoor
environment,  (b)  prevent  the  Release or threat of Release  or  minimize  the
further  Release of Hazardous  Materials so that they do not migrate or endanger
or  threaten  to  endanger  public  health or  welfare  or the indoor or outdoor
environment,   or  (c)  perform  pre-remedial  studies  and  investigations  and
post-remedial monitoring and care.

         "Reportable Event" means any of the events set forth in Section 4043 of
ERISA.

         "Required  Lenders"  means,  as of any date, any combination of Lenders
(other than any Defaulting Lenders) who collectively hold sixty percent (60%) of
the sum of the  Commitments  (other than of any Defaulting  Lenders),  or if the
Commitments  shall have been terminated,  then of the aggregate unpaid principal
amount of the Notes (other than of any Defaulting Lenders).


<PAGE>


         "Reserve  Requirement"  means,  for  any  Eurodollar  Advance  for  any
Interest  Period  therefor,  the average rate at which  reserves  (including any
marginal,  supplemental  or emergency  reserves)  are required to be  maintained
during such Interest Period under  Regulation D by each Lender on its portion of
such  Advance  against  "Eurocurrency  Liabilities"  as  such  term  is  used in
Regulation  D.  Without  limiting  the  effect  of the  foregoing,  the  Reserve
Requirement  shall  reflect any other  reserves  required to be  maintained by a
Lender  by  reason  of  any  Regulatory  Change  against  (i)  any  category  of
liabilities   which  includes  deposits  by  reference  to  which  the  Adjusted
Eurodollar  Rate is to be  determined,  or (ii) any  category of  extensions  of
credit or other assets which include Eurodollar Advances.

         "RICO" means the Racketeer  Influenced and Corrupt  Organization Act of
1970, as amended from time to time.

         "Senior  Debt"  means,  as of any date,  all Total  Funded  Debt of the
Companies which is not Subordinated Debt.

         "Senior Funded Debt" means, as to the Companies,  as of any date, Total
Funded Debt of such Persons, minus Subordinated Debt of such Persons.

         "Senior  Funded Debt to EBITDA Ratio" means,  as of any date, the ratio
of (a) the  aggregate  amount of Senior  Funded Debt of the  Companies  (without
deduction for any minority  interests),  as of such date, to (b) Adjusted EBITDA
of the  Companies,  for the four (4) fiscal quarter period ending on the date of
determination   (including  on  a  pro  forma  basis  any  Permitted  Refractive
Acquisition).

         "Senior  Subordinated  Indenture"  means that certain  Trust  Indenture
dated as of March 24, 1998 between Prime Medical and State Street Bank and Trust
Company, as Trustee, and any trust indenture entered into in connection with the
Exchange Notes.

         "Solvent"  means,  with  respect  to any  Person,  that on the  date of
determination  (a) the fair market value of its assets is greater than the total
amount of liabilities,  including, without limitation, contingent liabilities of
such Person which would be required to be included on the balance  sheet of such
Person or disclosed in the  financial  statements  of such Person in  accordance
with GAAP,  (b) the present fair  salable  value of the assets of such Person is
not less than the amount that will be required to pay the probable  liability of
such Person on its debts as they become  absolute and  matured,  (c) such Person
does not intend to, and does  believe that it will,  incur debts or  liabilities
beyond such Person's  ability to pay as such debts and liabilities  mature,  and
(d) such Person is not engaged in business or transactions,  and is not about to
engage in business or  transactions,  for which its assets would  constitute  an
unreasonably small capital.

         "Subordinated  Debt"  means  Debt due and  owing  from  time to time by
Borrower to Prime Medical,  Prime RVC, or PMOI  containing  terms  acceptable to
Administrative  Agent  and  Required  Lenders,  which  is  subordinated  to  the
Obligations in form and substance acceptable to the Administrative Agent and the
Required Lenders,  and which does not exceed  $16,000,000 in aggregate  original
principal amount.

         "Subsidiary"  means,  with  respect  to any  Person,  any  corporation,
partnership,  association,  or other business entity (a) of which  securities or
other  ownership  interests  representing  more than fifty  percent (50%) of the
equity or more than fifty  percent  (50%) of the  ordinary  voting power or more
than fifty  percent  (50%) of the general  partnership  interests or  membership
interests are, at the time any determination is made, owned,  Controlled or held
by such Person, or (b) that is, at the time any determination is made, otherwise
Controlled by one or more  Subsidiaries of such Person or by such Person and one
or more Subsidiaries of such Person.


<PAGE>


         "Target  Company"  means any  Person  that has been or may be  acquired
pursuant to a Permitted Refractive Acquisition permitted hereunder.

         "Termination  Date"  means  1:00 p.m.  Dallas,  Texas time on April 21,
2003,  or such  earlier  date and time on which  the  Commitments  terminate  as
provided in this Agreement.

     "Total Cash Flow"  means as to  Borrower,  for any period,  the sum of: (i)
EBITDA, plus (ii) all minority interest expense attributable to LASIK Investors,
L.L.C., minus (iv) the amount of Capital Expenditures.

         "Total  Funded Debt"  means,  as of any date,  outstanding  Debt of the
Companies (without deduction for minority interests).

         "Total Funded Debt to EBITDA Ratio" means, as of any date, the ratio of
(a) the  aggregate  amount  of Total  Funded  Debt  (without  deduction  for any
minority  interests),  as of such date, to (b) Adjusted EBITDA of the Companies,
for the four (4)  fiscal  quarter  period  ending  on the date of  determination
(including on a pro forma basis any Permitted Refractive Acquisition).

     "Type"  means any type of Advance  (i.e.,  Alternate  Base Rate  Advance or
Eurodollar Advance).

         "UCC"  means the Uniform  Commercial  Code as in effect in the State of
Texas or other applicable jurisdiction, as amended.

         "Wholly-Owned  Subsidiaries"  means,  as of any date, all  Subsidiaries
that are  wholly-owned  by Borrower or a  wholly-owned  Subsidiary  of Borrower.
"Wholly-Owned Subsidiary" means any one of the Wholly-Owned Subsidiaries.

         Section 1.3 Other Definitional Provisions. All definitions contained in
this  Agreement  are equally  applicable to the singular and plural forms of the
terms  defined.  The words  "hereof,"  "herein,"  and  "hereunder"  and words of
similar import  referring to this  Agreement  refer to this Agreement as a whole
and  not to  any  particular  provision  of  this  Agreement.  Unless  otherwise
specified, all Article, Section, Exhibit and Schedule references pertain to this
Agreement.  All  accounting  terms  not  specifically  defined  herein  shall be
construed  in  accordance  with  GAAP.  All  financial   covenants  and  related
definitions  relating to the Companies  shall,  unless otherwise  indicated,  be
determined  after  deduction  of  any  minority  interests,  provided  that  all
references to "Debt" shall  include all Debt without  deduction for any minority
interests.  Terms used  herein  that are  defined in the UCC,  unless  otherwise
defined herein, shall have the meanings specified in the UCC.

                             ARTICLE II -- ADVANCES

         Section 2.1       Commitments.


<PAGE>


         (a) Advancing Term Commitments.  Subject to the terms and conditions of
this Agreement, each Lender hereby severally agrees to make one or more Advances
to Borrower from time to time from the date hereof to the Termination Date in an
aggregate  principal  amount at any time outstanding up to but not exceeding the
amount of such Lender's  Commitment as then in effect.  Subject to the foregoing
limitations, and the other terms and provisions of this Agreement,  Borrower may
borrow,  the  amount  of the  Commitments  by means of  Eurodollar  Advances  or
Alternate Base Rate  Advances.  Advances which are repaid may not be reborrowed.
Advances  requested  hereunder to finance a portion of the  purchase  price of a
Permitted Refractive  Acquisition shall not exceed the lesser of: one-half (1/2)
of the total purchase price of the Permitted  Refractive  Acquisition,  and (ii)
two and one-half  (2.5) times the pro forma EBITDA of the Target Company for the
most recently completed four fiscal quarters.

         (b) Optional  Reduction and Termination of Commitments.  Borrower shall
have the right to terminate in whole or reduce in part the unused portion of the
Commitments  upon at least three (3) Business  Days' prior written notice (which
notice  shall  be  irrevocable)  to  the  Administrative  Agent  specifying  the
effective  date thereof,  whether a termination  or reduction is being made, and
the amount of any partial reduction,  provided that each partial reduction shall
be in the amount of  $1,000,000.00  or a greater  integral  multiple thereof and
Borrower shall  simultaneously  prepay the amount by which the unpaid  principal
amount of the Notes exceeds the Commitments (after giving effect to such notice)
plus accrued and unpaid interest on the principal amount so prepaid.  No portion
of the Commitments may be reinstated after it has been terminated or reduced.

         Section 2.2 Notes.  The obligation of Borrower to repay each Lender for
Advances  made by such Lender  pursuant  to such  Lender's  Commitment,  and all
interest thereon,  shall be evidenced by a Note dated the date hereof,  executed
by Borrower  and payable to the order of such Lender in the  original  principal
amount of such Lender's  Commitment.  Upon receipt of an affidavit of an officer
of any Lender to the loss, theft, destruction or mutilation of any Note, and, in
the case of any such loss, theft,  destruction or mutilation,  upon cancellation
of such Note,  Borrower will issue, in lieu thereof,  a replacement  note in the
same principal amount thereof and otherwise of like tenor.

     Section 2.3  Repayment of Notes.  Borrower  shall repay the Notes and apply
Total Cash Flow in the following order:

(1)  Interest  on the Notes shall be due and payable as set forth in Section 2.4
     below.

(2)  After  making  the  payments  when due set forth in Section  2.3(a)  above,
     Borrower  shall be permitted  to retain an  aggregate  amount of Total Cash
     Flow not exceeding $150,000 in each fiscal year for working capital.

                  (c) Prime  Refractive,  L.L.C.  and its  Partnerships may make
         Distributions  to  their  respective   partners  not  more  often  than
         quarterly,  limited  to an  amount  sufficient  to pay  such  partners'
         federal and state income tax liability  arising from their  partnership
         interest in the applicable Partnerships.

                  (d) Outstanding principal of the Notes will be due and payable
         quarterly on the last day of each January,  April,  July,  and October,
         commencing  January  31,  2000  in an  amount  equal  to the sum of the
         aggregate  amounts  which would be required to be paid on each  Advance
         made  hereunder  to  fully  amortize  each  Advance  in  sixteen  equal
         principal payments, but only to the extent Total Cash Flow is available
         to pay such amounts,  which amounts, if not fully paid on any quarterly
         payment  date  will be due and  payable  on each  succeeding  quarterly
         interest  payment  date,  to the extent Total Cash Flow is available to
         make such payments.


<PAGE>


               (e) Any  remaining  Total  Cash  Flow  may be  paid  as  interest
          payments on the Subordinated Indebtedness, when due and payable.

                  (f) All  remaining  Total Cash Flow,  not applied as set forth
         above,  shall be applied on the last day of each January,  April, July,
         and October, commencing January 31, 2000 to the unpaid principal amount
         of the Loans, pro rata, in the inverse order of maturity.

               (g) All outstanding  unpaid  principal of and accrued interest on
          the Notes shall be due and payable on the Termination Date.

         Section 2.4 Interest. The unpaid principal amount of all Advances shall
bear interest at a varying rate per annum equal from day to day to the lesser of
(a) the Maximum Rate, or (b) the Applicable  Rate. If at any time the Applicable
Rate for any Advance shall exceed the Maximum Rate, thereby causing the interest
accruing on such Advance to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate for such Advance shall not reduce the rate of
interest on such Advance  below the Maximum Rate until the  aggregate  amount of
interest  accrued on such Advance equals the aggregate  amount of interest which
would have accrued on such Advance if the Applicable  Rate had at all times been
in effect.  Accrued and unpaid interest on the Advances shall be due and payable
on each Payment Date and on the Termination Date. Notwithstanding the foregoing,
any outstanding principal of any Advance and (to the fullest extent permitted by
law) any other amount payable by Borrower under this Agreement or any other Loan
Document  that is not paid in full  when due  (whether  at stated  maturity,  by
acceleration,  or  otherwise)  shall bear  interest at the Default  Rate for the
period from and  including  the due date thereof to but  excluding  the date the
same is paid in full. Interest payable at the Default Rate shall be payable from
time to time on demand.

         Section 2.5       Borrowing Procedure.

         (a) Loan. Borrower shall give the Administrative  Agent notice by means
of an Advance  Request  Form of each  requested  Advance  under the  Commitments
hereunder at least three (3)  Business  Days before the  requested  date of each
Eurodollar  Advance (and at least one (1) Business Day before the requested date
of each Alternate Base Rate Advance), specifying: (a) the requested date of such
Advance (which shall be a Business Day); (b) the amount of such Advance; and (c)
the duration of the Interest Period for such Advance (if a Eurodollar  Advance).
The  Administrative  Agent at its  option  may accept  telephonic  requests  for
Advances  under  the  Commitments,  provided  that  such  acceptance  shall  not
constitute  a waiver  of the  Administrative  Agent's  right to  delivery  of an
Advance  Request  Form  in  connection   with  subsequent   Advances  under  the
Commitments.  Any  telephonic  request for an Advance under the  Commitments  by
Borrower  shall be promptly  confirmed  by  submission  of a properly  completed
Advance  Request  Form to the  Administrative  Agent.  Each  Advance  under  the
Commitments  shall be in a minimum  principal amount of $500,000.00 or a greater
integral  multiple  thereof,  provided  that if such  Advance  equals the entire
remaining  unfunded  portion of the Commitments,  it may be for any amount.  The
aggregate  principal  amount of  Eurodollar  Advances  having the same  Interest
Period shall be at least equal to $1,000,000.00.  All notices under this Section
2.5(a) shall be irrevocable and shall be given not later than 11:00 a.m. Dallas,
Texas  time on the day  which  is not less  than the  number  of  Business  Days
specified above for such notice.


<PAGE>


         (b) Generally.  The  Administrative  Agent shall  promptly  notify each
Lender of the contents of each Advance  Request Form.  Not later than 11:00 a.m.
Dallas, Texas time on the date specified for each Advance hereunder, each Lender
will make  available  to the  Administrative  Agent at the  Principal  Office in
immediately available funds, for the account of Borrower,  its pro rata share of
each Advance. After the Administrative Agent's receipt of such funds and subject
to the other terms and conditions of this Agreement,  the  Administrative  Agent
will  make each  Advance  available  to  Borrower  by  depositing  the same,  in
immediately  available funds, in a deposit account of Borrower maintained at the
Documentation Agent.

         Section 2.6       Continuations; Conversions.

         (a) Continuations. Borrower shall have the right to Continue Eurodollar
Advances by giving the Administrative  Agent written notice specifying:  (i) the
Continuation date; (ii) the amount of the Advance to be Continued; and (iii) the
duration of the  Interest  Period  applicable  thereto,  which  notice  shall be
irrevocable  and must be given by  Borrower  not later than  11:00 a.m.  Dallas,
Texas time at least three (3) Business Days before each such  Continuation.  The
Administrative  Agent shall promptly  notify each Lender of the contents of each
such notice. If Borrower shall fail to give the Administrative  Agent the notice
as specified above for Continuation of a Eurodollar  Advance prior to the end of
the  Interest  Period  applicable  thereto,  such  Eurodollar  Advance  shall be
automatically Continued for a one (1) month Interest Period.

         (b) Conversions.  Borrower shall have the right to Convert an Alternate
Base  Rate  Advance  at  any  time  to  a  Eurodollar   Advance  by  giving  the
Administrative  Agent written notice  specifying:  (i) the Conversion Date; (ii)
the  amount of the  Advance  to be  Converted;  and (iii)  the  duration  of the
Interest Period applicable  thereto,  which notice shall be irrevocable and must
be given by Borrower not later than 11:00 a.m. Dallas, Texas time at least three
(3) Business Days before each such Conversion.  The  Administrative  Agent shall
promptly notify each Lender of the contents of each such notice.

     (c) Default.  After the occurrence and during the continuance of a Default,
no  outstanding  Advances may be Converted  into,  or Continued as, a Eurodollar
Advance.

         Section  2.7 Use of  Proceeds.  The  proceeds  of  Advances  under  the
Commitments  shall  be used by  Borrower  (i) to  finance  Permitted  Refractive
Acquisitions and (ii) to finance capital expenditures.

         Section 2.8       Fees.

         (a)   Commitment   Fees.   Borrower   hereby   agrees  to  pay  to  the
Administrative   Agent,  for  the  ratable  account  of  each  Lender  having  a
Commitment, a commitment fee on the daily average unused amount of such Lender's
Commitment  for the period from and including the date of this  Agreement to but
excluding the  Termination  Date, at the per annum rate equal to the  Applicable
Unused  Fee  Percentage  based on a 360-day  year,  as the case may be,  and the
actual  number of days  elapsed.  Accrued  commitment  fees  shall be payable in
arrears on each Payment Date and on the Termination Date.

     (b) Agents' Fees. Borrower hereby agrees to pay to the Agents for their own
respective accounts, the fees agreed to by Borrower and the Agents pursuant to a
side letter agreement with each Agent.


                             ARTICLE III -- PAYMENTS


<PAGE>


         Section 3.1 Method of Payment. All payments of principal, interest, and
other  amounts to be paid by Borrower  under this  Agreement  and the other Loan
Documents shall be paid to the Administrative  Agent at the Principal Office for
the  account  of each  Lender's  Applicable  Lending  Office in  Dollars  and in
immediately  available funds, without setoff,  deduction,  or counterclaim,  not
later than 1:00 p.m. Dallas,  Texas time on the date on which such payment shall
become due (each such payment made after such time on such due date to be deemed
to have been made on the next succeeding  Business Day).  Borrower shall, at the
time of making each such payment,  specify to the Administrative  Agent the sums
payable by Borrower  under this  Agreement and the other Loan Documents to which
such  payment  is to be  applied  (and in the event  that  Borrower  fails to so
specify,  or if an  Event  of  Default  has  occurred  and  is  continuing,  the
Administrative Agent may apply such payment to the Obligations in such order and
manner as it may elect in its sole  discretion,  subject to Section  3.4).  Each
payment received by the  Administrative  Agent under this Agreement or any other
Loan Document for the account of a Lender shall be paid promptly to such Lender,
in  immediately  available  funds,  for the account of such Lender's  Applicable
Lending  Office.  Whenever  any payment  under this  Agreement or any other Loan
Document  shall be stated to be due on a day that is not a  Business  Day,  such
payment may be made on the next  succeeding  Business Day, and such extension of
time  shall in such  case be  included  in the  computation  of the  payment  of
interest and commitment fee, as the case may be.

         Section 3.2 Optional Prepayment.  Borrower may, upon at least three (3)
Business  Days' prior notice to the  Administrative  Agent,  prepay the Notes in
whole or in part at any time or from time to time without premium or penalty but
with  accrued  interest  to the date of  prepayment  on the  amount so  prepaid,
provided that  Eurodollar  Advances  prepaid on a day other than the last day of
the Interest Period for such Advances shall include the additional compensation,
if any,  required by Section  4.5.  All notices  under this Section 3.2 shall be
irrevocable  and must be given by  Borrower  not later than  11:00 a.m.  Dallas,
Texas  time on the day  which  is not less  than the  number  of  Business  Days
specified above for such notice.  Optional  prepayments  shall be applied as set
forth in Section 3.8.

         Section 3.3 Pro Rata Treatment. Except to the extent otherwise provided
herein:  (a) the making and  Continuation of Advances under the Commitment shall
be made pro rata among the Lenders  according to the amounts of their respective
Commitments;  (b) each termination or reduction of the Commitments under Section
2.1(b) or otherwise shall be applied to the Commitments of the Lenders pro rata,
according  to their  respective  unused  Commitments;  and (c) each  payment and
prepayment of principal of or interest on Advances by Borrower  shall be made to
the Administrative Agent for the account of the applicable Lenders in accordance
with Section 3.9.

         Section 3.4 Non-Receipt of Funds by the  Administrative  Agent.  Unless
the  Administrative  Agent shall have been notified by a Lender or Borrower (the
"Payor")  prior to the date on  which  such  Lender  is to make  payment  to the
Administrative Agent of the proceeds of an Advance to be made by it hereunder or
Borrower is to make a payment to the Administrative Agent for the account of one
or more of the Lenders, as the case may be (such payment being herein called the
"Required  Payment"),  which notice shall be effective  upon  receipt,  that the
Payor does not intend to make the Required Payment to the Administrative  Agent,
the Administrative  Agent may assume that the Required Payment has been made and
may, in reliance upon such  assumption  (but shall not be required to), make the
amount  thereof  available  to the  intended  recipient on such date and, if the
Payor has not in fact made the Required Payment to the Administrative Agent, the
recipient of such payment shall, on demand,  return to the Administrative  Agent
the amount made available to it together with interest thereon in respect of the
period  commencing  on the  date  such  amount  was  so  made  available  by the
Administrative  Agent  until the date the  Administrative  Agent  recovers  such
amount at a rate per annum equal to the Federal Funds Rate for such period.


<PAGE>


         Section 3.5 Withholding Taxes. All payments by Borrower of principal of
and interest on the Advances and of all fees and other amounts payable under any
Loan Document are payable without  deduction for or on account of any present or
future taxes,  duties or other charges levied or imposed by the United States of
America or by the  government of any  jurisdiction  outside the United States of
America or by any political  subdivision or taxing authority of or in any of the
foregoing through withholding or deduction with respect to any such payments. If
any such taxes, duties or other charges are so levied or imposed,  Borrower will
pay additional interest or will make additional payments in such amounts so that
every net payment of  principal of and interest on the Advances and of all other
amounts  payable by any of them under any Loan  Document,  after  withholding or
deduction for or on account of any such present or future taxes, duties or other
charges,  will not be less than the  amount  provided  for  herein  or  therein,
provided that Borrower shall have no obligation to pay such  additional  amounts
to any Lender to the extent that such taxes, duties, or other charges are levied
or imposed by reason of the failure of such Lender to comply with the provisions
of Section 3.6. Borrower shall furnish promptly to the Administrative  Agent for
distribution  to each affected  Lender,  as the case may be,  official  receipts
evidencing any such withholding or reduction.

         Section  3.6  Withholding  Tax  Exemption.  Each  Lender  that  is  not
incorporated  under the laws of the United  States of America or a state thereof
agrees that it will  deliver to Borrower  and the  Administrative  Agent two (2)
duly completed  copies of United States  Internal  Revenue  Service Form 1001 or
4224, certifying in either case that such Lender is entitled to receive payments
from Borrower under any Loan Document,  without  deduction or withholding of any
United States federal  income taxes or (b) if such Lender is claiming  exemption
from United States  withholding  tax under Section  871(h) or 881(c) of the Code
with respect to payments of  "portfolio  interest," a Form W-8, or any successor
form prescribed by the Internal Revenue Service, and a certificate  representing
that such Lender is not a bank for  purposes of Section  881(c) of the Code,  is
not a 10-percent  shareholder (within the meaning of Section 871(h)(3)(B) of the
Code) of the Borrower and is not a controlled foreign corporation related to the
Borrower  (within the  meaning of Section  864(d)(4)  of the Code).  Each Lender
which so  delivers a W-8,  Form 1001 or 4224  further  undertakes  to deliver to
Borrower and the Administrative Agent two (2) additional copies of such form (or
a successor form) on or before the date such form expires or becomes obsolete or
after the occurrence of any event  requiring a change in the most recent form so
delivered by it, and such amendments  thereto or extensions or renewals  thereof
as may be reasonably requested by Borrower or the Administrative  Agent, in each
case certifying  that such Lender is entitled to receive  payments from Borrower
under any Loan Document  without  deduction or  withholding of any United States
federal income taxes,  unless an event (including  without limitation any change
in treaty,  law or regulation)  has occurred prior to the date on which any such
delivery would  otherwise be required which renders all such forms  inapplicable
or which would prevent such Lender from duly  completing and delivering any such
form with respect to it and such Lender advises Borrower and the  Administrative
Agent that it is not capable of receiving such payments without any deduction or
withholding of United States federal income tax.

         Section 3.7  Computation of Interest.  Interest on all Advances and all
other amounts payable by Borrower  hereunder shall be computed on the basis of a
year of 360 days, and actual days elapsed.

         Section 3.8       Order of Application.

         (a) No  Default.  Prior to the  occurrence  of an Event of Default  any
payment  (whether  voluntary or  mandatory) of the Notes shall be applied to the
Notes on a pro rata basis based upon the outstanding  principal  balances of the
Notes as of the date of payment. No payment on the Notes may be reborrowed.


<PAGE>


         (b) After Default.  After the occurrence and during the  continuance of
an Event of Default,  any payment or proceeds of Collateral  shall be applied in
the  following  order:  (i) to all fees and expenses for which Agents or Lenders
have not been paid or reimbursed in accordance  with the Loan  Documents (and if
such payment is less than all unpaid or unreimbursed fees and expenses, then the
payment shall be paid against unpaid and  unreimbursed  fees and expenses in the
order of incurrence or due date); (ii) to accrued interest on the Notes on a pro
rata basis, based upon the outstanding principal balances of the Notes as of the
date of payment;  (iii) to the  principal of the Notes and amounts due and owing
under  any  Financial  Hedge on a pro rata  basis,  based  upon the  outstanding
principal  balances of the Notes or obligation due and owing under any Financial
Hedge as of the date of payment; and (iv) to all other Obligations.

         (c) Application to Advances.  Subject to the foregoing,  and so long as
no Event of Default has occurred and is continuing, payments of principal of any
Note shall be applied  to such  outstanding  Alternate  Base Rate  Advances  and
Eurodollar Advances under such Note as Borrower shall select; provided, however,
that Borrower shall select Alternate Base Rate Advances and Eurodollar  Advances
to be repaid in a manner  designated to minimize the funding loss required to be
paid pursuant to Section 4.5, if any, resulting from such payment;  and provided
further that if Borrower  shall fail to select the Alternate  Base Rate Advances
and Eurodollar Advances to which such payments are to be applied, or if an Event
of Default has occurred and is continuing at the time of such payment,  then the
Administrative  Agent shall be entitled to apply the payment to such Advances in
the manner in which it shall deem appropriate in its sole discretion.

                  ARTICLE IV -- YIELD PROTECTION AND ILLEGALITY

         Section 4.1       Additional Costs.

         (a) Borrower  hereby agrees to pay directly to each Lender from time to
time such amounts as such Lender may  determine to be necessary to compensate it
for  any  costs  incurred  by such  Lender  which  such  Lender  determines  are
attributable to its making or maintaining any Eurodollar  Advances  hereunder or
its obligation to make any of such Advances  hereunder,  or any reduction in any
amount  receivable  by such Lender  hereunder in respect of any such Advances or
such obligation  (such  increases in costs and reductions in amounts  receivable
being herein called  "Additional  Costs"),  resulting from any Regulatory Change
which:

                  (i) changes  the basis of  taxation of any amounts  payable to
         such Lender under this Agreement or its Notes in respect of any of such
         Advances  (other  than (1) taxes  imposed on the  overall net income of
         such Lender or its Applicable  Lending Office for any of such Advances,
         (2) franchise or similar taxes of such Lender, and (3) amounts withheld
         pursuant to the last sentence of Section 3.7);

                  (ii) imposes or modifies any reserve, special deposit, minimum
         capital,   capital  ratio,  or  similar  requirement  relating  to  any
         extensions  of credit or other assets of, or any deposits with or other
         liabilities or commitments of, such Lender; or

                  (iii)  imposes  any  other   Additional  Cost  affecting  this
         Agreement  or the  Notes  or any  of  such  extensions,  of  credit  or
         liabilities or commitments.


<PAGE>


Each Lender will notify  Borrower of any event  occurring after the date of this
Agreement  which will  entitle  such  Lender to  compensation  pursuant  to this
Section 4.1(a) as promptly as practicable after it obtains knowledge thereof and
determines  to  request  such  compensation,  and  will  designate  a  different
Applicable  Lending  Office  for the  Advances  affected  by such  event if such
designation will avoid the need for, or reduce the amount of, such  compensation
and will not, in the sole  opinion of such  Lender,  violate any law,  rule,  or
regulation or be in any way  disadvantageous to such Lender,  provided that such
Lender shall have no  obligation to so designate an  Applicable  Lending  Office
located outside the United States of America.  Each Lender will furnish Borrower
with a  certificate  setting  forth the basis and the amount of each  request of
such Lender for compensation  under this Section 4.1(a).  If any Lender requests
compensation from Borrower under this Section 4.1(a), Borrower may, by notice to
such Lender (with a copy to the Administrative  Agent) suspend the obligation of
such Lender to make or Continue making Eurodollar  Advances until the Regulatory
Change  giving rise to such  request  ceases to be in effect (in which case such
Lender's  Eurodollar Advances shall be Converted to Alternate Base Rate Advances
in accordance with the provisions of Section 4.4).

         (b) Without  limiting the effect of the  foregoing  provisions  of this
Section 4.1, in the event that, by reason of any Regulatory  Change,  any Lender
either (i) incurs  Additional  Costs based on or measured by the excess  above a
specified level of the amount of a category of deposits or other  liabilities of
such Lender which  includes  deposits by reference to which the interest rate on
Eurodollar Advances is determined as provided in this Agreement or a category of
extensions  of credit or other assets of such Lender which  includes  Eurodollar
Advances  or (ii)  becomes  subject  to  restrictions  on the  amount  of such a
category of  liabilities  or assets which it may hold,  then,  if such Lender so
elects by notice to  Borrower  (with a copy to the  Administrative  Agent),  the
obligation  of such  Lender  to  make or  Continue  making  Eurodollar  Advances
hereunder shall be suspended until such Regulatory Change ceases to be in effect
(in which case such Lender's Eurodollar Advances shall be Converted to Alternate
Base Rate Advances in accordance with the provisions of Section 4.4).

         (c)  Determinations  and allocations by any Lender for purposes of this
Section 4.1 of the effect of any  Regulatory  Change on its costs of maintaining
its  obligations  to make  Advances or of making or  maintaining  Advances or on
amounts  receivable by it in respect of Advances,  and of the additional amounts
required to compensate such Lender in respect of any Additional Costs,  shall be
conclusive,  absent  manifest  error and provided that such  determinations  and
allocations are made on a reasonable basis.

     Section 4.2  Limitation  on  Eurodollar  Advances.  Anything  herein to the
contrary  notwithstanding,  if with  respect to any  Eurodollar  Advance for any
Interest Period therefor:

         (a) The Administrative  Agent determines (which  determination shall be
conclusive  absent  manifest  error) that  quotations of interest  rates for the
relevant  deposits referred to in the definition of "Eurodollar Rate" in Section
1.1  are  not  being  provided  in the  relative  amounts  or for  the  relative
maturities for purposes of determining the rate of interest for such Advances as
provided in this Agreement; or

         (b) The  Required  Lenders  determine  (which  determination  shall  be
conclusive absent manifest error) and notify the  Administrative  Agent that the
rate of interest  referred to in the definition of "Eurodollar  Rate" in Section
1.1 on the  basis  of which  the rate of  interest  for such  Advances  for such
Interest  Period is to be determined do not  accurately  reflect the cost to the
Lenders of making or maintaining such Advances for such Interest Period;

then  the  Administrative  Agent  shall  give  Borrower  prompt  notice  thereof
specifying  the  relevant  amounts  or  periods,  and so long as such  condition
remains in effect,  the Lenders shall be under no obligation to make or Continue
additional  Eurodollar  Advances and Borrower  shall,  on the last day(s) of the
then-current Interest Period(s) for the outstanding Eurodollar Advances,  prepay
such  Eurodollar  Advances or Convert  them to Alternate  Base Rate  Advances in
accordance with Section 4.4.


<PAGE>


         Section 4.3  Illegality.  Notwithstanding  any other  provision of this
Agreement,  in the  event  that  it  becomes  unlawful  for  any  Lender  or its
Applicable  Lending  Office  to (a)  honor  its  obligation  to make  Eurodollar
Advances hereunder,  or (b) maintain  Eurodollar  Advances hereunder,  then such
Lender shall promptly notify Borrower (with a copy to the Administrative  Agent)
thereof and such  Lender's  obligation to make or maintain  Eurodollar  Advances
shall be  suspended  until such time as such Lender may again make and  maintain
Eurodollar  Advances (in which case such Lender's  Eurodollar  Advances shall be
Converted to Alternate  Base Rate Advances in accordance  with the provisions of
Section 4.4).

         Section  4.4  Treatment  of  Eurodollar  Advances.  If  the  Eurodollar
Advances of any Lender are to be Converted  pursuant to Section 4.1, 4.2 or 4.3,
such  Lender's  Eurodollar  Advances  shall  be  automatically   Converted  into
Alternate  Base Rate  Advances on the last day(s) of the then  current  Interest
Period(s) for the Eurodollar  Advances (or, in the case of a Conversion required
by Section 4.1(b) or 4.3(b),  on such earlier date as such Lender may specify to
Borrower  with a copy to the  Administrative  Agent) and,  unless and until such
Lender  gives  notice as  provided  below that the  circumstances  specified  in
Section 4.1, 4.2 or 4.3 which gave rise to such Conversion no longer exist:

         (a) To the extent that such Lender's  Eurodollar  Advances have been so
Converted,  all payments and  prepayments of principal  which would otherwise be
applied to such Lender's  Eurodollar  Advances  shall be applied  instead to its
Alternate Base Rate Advances; and

         (b) All  Advances  which would  otherwise  be made or Continued by such
Lender as Eurodollar  Advances shall be made as or Converted into Alternate Base
Rate Advances.

If such  Lender  gives  notice to  Borrower  (with a copy to the  Administrative
Agent) that the circumstances specified in Section 4.1, 4.2 or Section 4.3 which
gave rise to the  Conversion of such Lender's  Eurodollar  Advances  pursuant to
this Section 4.4 no longer exist (which such Lender  agrees to do promptly  upon
such  circumstances  ceasing to exist) at a time when Advances are  outstanding,
such Lender's Alternate Base Rate Advances shall be automatically  Converted, on
the first day(s) of the next succeeding  Interest Period(s) for such outstanding
Eurodollar  Advances  to the  extent  necessary  so that,  after  giving  effect
thereto,  all Eurodollar  Advances held by the Lenders holding the same are held
pro rata (as to principal amounts and Interest Periods) in accordance with their
respective Commitments.

         Section  4.5  Compensation.  Borrower  shall pay to the  Administrative
Agent,  for the account of each Lender,  upon the request of such Lender through
the Administrative  Agent, such amount or amounts as shall be sufficient (in the
reasonable  opinion of such  Lender) to  compensate  it for any loss,  cost,  or
expense incurred by it as a result of:

         (a) Any payment,  prepayment or Conversion of a Eurodollar  Advance for
any reason (including,  without limitation,  the acceleration of the outstanding
Advances  pursuant  to  Section  11.2) on a date  other  than the last day of an
Interest Period for such Advance; or

         (b)  Any  failure  by  Borrower  for  any  reason  (including,  without
limitation,  the failure of any conditions  precedent specified in Article VI to
be  satisfied)  to borrow or prepay a  Eurodollar  Advance  on the date for such
borrowing  or  prepayment,  specified  in the  relevant  notice of  borrowing or
prepayment under this Agreement.


<PAGE>


Such  compensation  shall not exceed the  excess,  if any,  of (i) the amount of
interest which otherwise  would have accrued on the principal  amount so paid or
not  borrowed  for the period from the date of such payment or failure to borrow
to the last day of the  Interest  Period for such  Advance (or, in the case of a
failure  to  borrow,  the  Interest  Period for such  Advance  which  would have
commenced on the date specified for such  borrowing) at the  applicable  rate of
interest for such Advance  provided for herein over (ii) the interest  component
of the amount  such  Lender  would have bid in the London  interbank  market for
Dollar deposits of leading banks and amounts comparable to such principal amount
and with maturities comparable to such period.

         Section  4.6 Capital  Adequacy.  If after the date  hereof,  any Lender
shall have determined that the adoption or implementation of any applicable law,
rule, or regulation regarding capital adequacy  (including,  without limitation,
any law,  rule,  or regulation  implementing  the Basle  Accord),  or any change
therein,  or any change in the  interpretation or administration  thereof by any
central bank or other Governmental  Authority charged with the interpretation or
administration  thereof,  or  compliance by such Lender (or its parent) with any
guideline,  request,  or directive  regarding  capital adequacy  (whether or not
having the force of law) of any  central  bank or other  Governmental  Authority
(including,  without limitation, any guideline or other requirement implementing
the Basle  Accord),  has or would have the effect of reducing the rate of return
on such Lender's (or its parent's)  capital as a consequence of its  obligations
hereunder or the  transactions  contemplated  hereby to a level below that which
such  Lender  (or  its  parent)  could  have  achieved  but for  such  adoption,
implementation,  change or compliance  (taking into  consideration such Lender's
policies with respect to capital adequacy) by an amount deemed by such Lender to
be material,  then from time to time, within ten (10) Business Days after demand
by such Lender (with a copy to the Administrative  Agent), which demand shall be
delivered  by such Lender to Borrower  as  promptly  as  practicable  after such
Lender obtains knowledge of such reduction in its rate of return, Borrower shall
pay to such Lender such  additional  amount or amounts as will  compensate  such
Lender (or its parent) for such reduction. A certificate of such Lender claiming
compensation  under this  Section and  setting  forth the  additional  amount or
amounts to be paid to it hereunder  shall be conclusive,  absent  manifest error
and provided that the  determination  thereof is made on a reasonable  basis. In
determining such amount or amounts, such Lender may use any reasonable averaging
and attribution methods.

                              ARTICLE V -- SECURITY

         Section 5.1  Collateral.  To secure the full and  complete  payment and
performance of the  Obligations,  Borrower shall execute and deliver or cause to
be executed and delivered the documents  described  below  covering the property
and collateral  described  therein (which,  together with any other property and
collateral  which  may now or  hereafter  secure  the  Obligations  or any  part
thereof, is sometimes herein called the "Collateral"):

     (a) Borrower Security Agreement.  Borrower shall execute and deliver to the
Administrative  Agent,  for the benefit of the Lenders,  the  Borrower  Security
Agreement.

     (b) Guarantor Security Agreement.  The Guarantors shall execute and deliver
to the Administrative Agent, for the benefit of the Lenders,  Guarantor Security
Agreements.

     (c)  Pledge   Agreement.   Pledgors   shall  execute  and  deliver  to  the
Administrative Agent, for the benefit of the Lenders, the Pledge Agreements.


<PAGE>



         (d) Further Assurances. Borrower shall execute and cause to be executed
such further documents and instruments,  including without  limitation,  Uniform
Commercial  Code  financing  statements,  as the  Administrative  Agent  and the
Documentation  Agent, in their sole  discretion,  deem necessary or desirable to
evidence and perfect the Administrative  Agent's liens and security interests in
the Collateral.

     (e) Description of Collateral. Collateral includes, without limitation, the
following assets of Borrower and Guarantors:

                  (i) All present and future accounts,  contract rights, general
         intangibles,   chattel  paper,   documents,   instruments,   investment
         property, inventory,  equipment, and other goods, wherever located, now
         owned or hereafter acquired.

                  (ii) All present and future issued and  outstanding  shares of
         capital stock of, or partnership and membership interests, now owned or
         hereafter  acquired by Borrower or any  Guarantor,  including,  without
         limitation,  all  capital  stock  of,  or  partnership  and  membership
         interests in, the Guarantors.

                  (iii) To the  extent  allowed  by the  respective  partnership
         agreements,  certain  partnership  interests  or economic  interests in
         partnership interests owned by Borrower and Guarantors.

                  (iv)  All  present  and  future  automobiles,   trucks,  truck
         tractors, trailers,  semi-trailers,  or other motor vehicles or rolling
         stock now owned or  hereafter  acquired by  Borrower  or any  Guarantor
         (collectively, the "Vehicles").

                  (v) All present and future  rights,  awards,  and judgments to
         which  Borrower or any Guarantor is entitled  under any  litigation now
         existing or hereafter arising.

                  (vi) All present and future rights,  titles,  and interests of
         Borrower or any Guarantor in and to all patents,  patent  applications,
         patent right,  service marks,  trademarks,  tradenames,  trade secrets,
         intellectual property, registrations, goodwill, copyrights, franchises,
         licenses,  permits,  proprietary information,  customer lists, designs,
         and inventions.

                  (vii) All  present and future  books,  records,  data,  plans,
         manuals,  computer  software  and  computer  programs of  Borrower  and
         Guarantors.

               (viii) All  proceeds and  products of the  Collateral  heretofore
          described.

     Provided  that  the  Collateral  owned by the  Guarantor  under  the  Prime
Facility  shall be subject  to a first  lien in favor of the agents and  lenders
under the Prime Facility.

         Collateral shall also include LASIK Investors, LLC's interests in Prime
Refractive,  LLC,,  now owned or hereafter  acquired and all assets  financed by
Prime Refractive, LLC.


<PAGE>


         Section 5.2 Future Liens.  Promptly, and in any event within twenty-one
(21) days after (a) the acquisition of any assets (real, personal,  tangible, or
intangible)  by Borrower or any  Guarantor or (b) the removal,  termination,  or
expiration  of any  prohibition  upon the granting of a lien in any asset (real,
personal,  tangible, or intangible) of any Borrower or any Guarantor (including,
without limitation, the granting of liens in all general and limited partnership
interests  in  which  Borrower  and  Guarantors  own  100%  of  the  partnership
interests) (the "Additional Assets"),  Borrower shall (or shall cause such other
Guarantor  to)  execute  and  deliver  to   Administrative   Agent  all  further
instruments  and documents  (including,  without  limitation,  certificates  and
instruments  representing  shares  of stock or  evidencing  Debt and any  realty
appraisals  as  Administrative  Agent  may  require  with  respect  to any  such
Additional Assets), and shall take all such further action that may be necessary
or desirable,  or that  Administrative  Agent may reasonably  request, to grant,
perfect,  and protect liens in favor of Administrative  Agent for the benefit of
Lenders in such Additional  Assets,  as security for the  Obligations;  it being
expressly  understood  that the  granting of such  additional  security  for the
Obligations  is a material  inducement  to the  execution  and  delivery of this
Agreement by each Lender.  Upon satisfying the terms and conditions hereof, such
Additional  Assets shall be included in the  "Collateral" for all purposes under
the Loan Documents, and all references to the "Collateral" in the Loan Documents
shall include the Additional Assets.

         Section  5.3  Release  of  Collateral.  Upon  any  sale,  transfer,  or
disposition  of  Collateral  which is expressly  permitted  pursuant to the Loan
Documents  (or is otherwise  authorized by Required  Lenders or Lenders,  as the
case may be), and upon ten (10) Business Days' prior written request by Borrower
(which  request  must be  accompanied  by true  and  correct  copies  of (a) all
documents of transfer or  disposition,  including  any  contract of sale,  (b) a
preliminary closing statement and instructions to the title company, if any, and
(c) all requested release instruments, Administrative Agent shall (and is hereby
irrevocably  authorized  by the  Lenders to) execute  such  documents  as may be
necessary to evidence the release of liens granted to  Administrative  Agent for
the benefit of lenders pursuant hereto in such Collateral; provided that, (x) no
such  release of Lien shall be  granted if any  Default or Event of Default  has
occurred and is continuing,  including,  without limitation, the failure to make
certain mandatory prepayments in accordance with Section 2.3 in conjunction with
the sale and transfer of such Collateral;  (y) Administrative Agent shall not be
required to execute any such document on terms which, in Administrative  Agent's
opinion, would expose Administrative Agent to liability or create any obligation
or entail any consequence, other than the release of such Liens without recourse
or warranty; and (z) such release shall not in any manner discharge,  affect, or
impair  the  Obligations,  or  liens  upon or  obligations  of  Borrower  or any
Guarantor in respect of all interests  retained by the Borrower and  Guarantors,
including,  without  limitation,  the  proceeds of any sale,  all of which shall
continue to constitute Collateral.

         Section 5.4 Setoff.  If an Event of Default  shall have occurred and is
continuing,  each Lender is hereby authorized at any time and from time to time,
without  notice to Borrower  (any such notice being hereby  expressly  waived by
Borrower),  to set off and apply any and all deposits (general or special,  time
or demand,  provisional or final) at any time held and other indebtedness at any
time  owing by such  Lender to or for the  credit  or the  account  of  Borrower
against any and all of the  obligations  of Borrower now or  hereafter  existing
under  this  Agreement,  such  Lender's  Notes,  or  any  other  Loan  Document,
irrespective  of whether or not the  Administrative  Agent or such Lender  shall
have made any demand under this  Agreement or such Lender's  Notes or such other
Loan Document and although such obligations may be unmatured. Each Lender agrees
promptly to notify Borrower (with a copy to the Administrative  Agent) after any
such setoff and application, provided that the failure to give such notice shall
not affect the validity of such setoff and application.  The rights and remedies
of  each  Lender  hereunder  are  in  addition  to  other  rights  and  remedies
(including,  without  limitation,  other rights of setoff) which such Lender may
have.


<PAGE>


                       ARTICLE VI -- CONDITIONS PRECEDENT

         Section 6.1 Initial Advance.  The obligation of each Lender to make its
initial  Advance is subject to the condition  precedent that the  Administrative
Agent  shall  have  received  on or before  the day of such  Advance  all of the
following,  each dated (unless otherwise indicated) the date hereof, in form and
substance satisfactory to the Administrative Agent:

         (a) Resolutions. Resolutions of the Boards of Directors of Borrower and
each Guarantor  certified by the Secretary or an Assistant  Secretary of each of
them which authorize the execution, delivery, and performance by such Company of
this Agreement and/or the other Loan Documents to which such Company is or is to
be a party;

         (b) Incumbency  Certificate.  A certificate of incumbency  certified by
the  Secretary  or  an  Assistant  Secretary  of  Borrower  and  each  Guarantor
certifying  the names of the officers of each such  Company,  authorized to sign
this  Agreement and each of the other Loan  Documents to which each such Company
is or is to be a party (including the certificates contemplated herein) together
with specimen signatures of such officers;

     (c) Articles of  Incorporation.  The articles of  incorporation of Borrower
and each Guarantor certified by the appropriate governmental office;

     (d) Bylaws.  The bylaws of Borrower  and each  Guarantor  certified  by the
Secretary or an Assistant Secretary of each such Company;

     (e) Governmental  Certificates.  Certificates of the appropriate government
officials  of the  state  of  incorporation  of  Borrower  and  Litho  as to the
existence and good standing of each of them;

         (f)      Notes.  The Notes executed by Borrower;

     (g) Borrower Security  Agreement.  Borrower Security  Agreement executed by
Borrower;

         (h)      Guaranties.  The Guaranty Agreements executed by Guarantors;

     (i)  Guarantor  Security  Agreement.   The  Guarantor  Security  Agreements
executed by the Guarantors;

     (j) Pledge Agreements.  The Pledge and Security  Agreements executed by the
Pledgors;

     (k) Financing  Statements.  Uniform  Commercial  Code financing  statements
executed  by  Borrower  and each  Guarantor  and  covering  the  Collateral,  as
requested by Administrative Agent;

     (l) Stock  Certificates.  Stock  certificates  evidencing all stock pledged
pursuant  to  the  Borrower  Security  Agreement  and  each  Guarantor  Security
Agreement, as applicable, together with stock powers duly executed in blank, and
acknowledgements  by the  Prime  Agent,  of the  second  liens in stock  created
thereunder;



<PAGE>


     (m) Certificates of Title.  Original  certificates of title,  together with
executed  applications  for title,  for all vehicles used in connection with the
transportation  of  lithotripters  pledged  pursuant  to the  Borrower  Security
Agreement and the Guarantor Security Agreements;

     (n)  Insurance  Policies.  Copies of all  insurance  policies  required  by
Section  8.5,   together   with  loss  payee   endorsements   in  favor  of  the
Administrative  Agent,  for the  benefit  of the  Lenders,  with  respect to all
insurance policies covering Collateral;

         (o) UCC and Tax and  Judgment  Lien  Searches.  The  results of Uniform
Commercial Code searches showing all financing statements and other documents or
instruments,  and tax and judgment  lien  searches  showing all tax and judgment
liens,  on file against  Borrower and  Guarantors in such  jurisdictions  as the
Administrative  Agent shall  require,  such  searches to be as of a date no more
than twenty (20) days prior to the date of the initial Advance;

     (p) Perfection Certificate. A Perfection Certificate,  in substantially the
form of Exhibit D hereto,  properly  completed and signed by the Chief Executive
or  Chief  Financial  Officer  or Vice  President-Finance  of  Borrower  and the
Guarantors;

     (q) Opinion of Counsel.  Favorable  opinions as to the matters set forth in
Exhibit E hereto of Akin,  Gump,  Strauss,  Hauer & Feld,  L.L.P.,  Texas  legal
counsel to Borrower and the Guarantors.

     (r)  Closing  of Prime  Facility.  Evidence  that the  closing of the Prime
Facility  has  occurred  and  contains  terms  and   conditions   acceptable  to
Administrative Agent.

     (s)  Attorneys'  Fees and  Expenses.  Evidence  that the costs and expenses
(including attorneys' fees) referred to in Section 13.1, to the extent incurred,
shall have been paid in full by Borrower;

         (t)  Fees.  Borrower  shall  have  paid  to the  Administrative  Agent,
Lenders,  and Lead  Arranger  the fees owed by  Borrower  to the  Administrative
Agent,  Lenders,  and Lead Arranger  pursuant to the letter  agreements  between
Borrower and Administrative Agent;

     (t) Federal Reserve Board Form U-1. For the Administrative Agent a properly
completed  Federal Reserve Board Form U-1 duly executed by each Company pledging
stock of another Company; and

         (u) No Material  Adverse Change.  No material adverse change shall have
occurred  since  September  30,  1999  in  the  business,   assets,  operations,
conditions  (financial  or  otherwise)  or  prospects  of Prime  Medical and its
Subsidiaries  or of the Companies or in the facts and  information  delivered to
Lenders on or prior to the date of the initial Advance.

     Section 6.2 All Advances. The obligation of each Lender to make any Advance
(including  the  initial  Advance)  is  subject  to  the  following   additional
conditions precedent:

     (a) Advance Request Form. The Administrative Agent shall have received,  in
accordance  with Section 2.5, an Advance  Request Form executed by an authorized
officer of Borrower;



<PAGE>


     (b) No Default. No Default shall have occurred and be continuing,  or would
result from such Advance;

         (c)  Representations  and Warranties.  All of the  representations  and
warranties  contained  in  Article  VII  hereof  and in each of the  other  Loan
Documents  shall be true and correct on and as of the date of such  Advance with
the same force and effect as if such  representations  and  warranties  had been
made on and as of such date, except to the extent that such  representations and
warranties  speak to a specific date or the facts on which such  representations
and warranties are based have been changed by  transactions  contemplated by the
Loan Documents;

     (d) Permitted Refractive Acquisitions.  The amount of any Advance hereunder
to  finance  a  portion  of  the  purchase  price  of any  Permitted  Refractive
Acquisition  shall not exceed the lesser of: (a) one-half of the total  purchase
price,  or (b) 2.5 times the pro forma EBITDA of the Target Company for the most
recently completed four fiscal quarters; and

     (e) Additional Documentation.  The Administrative Agent shall have received
such additional  approvals,  opinions, or documents as are required by the terms
and provisions of this Agreement or any other Loan Document.


                  ARTICLE VII -- REPRESENTATIONS AND WARRANTIES

         To induce  the Agents  and the  Lenders  to enter into this  Agreement,
Borrower hereby represents and warrants to the Agents and the Lenders that:

         Section 7.1       Existence.

         (a)  Corporate  Existence.  Each  of  the  Companies  (other  than  the
Partnerships and the Guarantors):  (a) is a corporation duly organized,  validly
existing,  and in  good  standing  under  the  laws of the  jurisdiction  of its
incorporation;  (b) has all requisite  corporate  power and authority to own its
assets and carry on its  business as now being or as  proposed to be  conducted;
and (c) is qualified to do business in all  jurisdictions in which the nature of
its business makes such qualification  necessary and where failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Borrower,  or any Guarantor.  Each Company has the corporate power and authority
to execute,  deliver,  and perform its obligations  under this Agreement and the
other Loan Documents to which it is or may become a party.

         (b) Partnership  Existence.  Each of the Partnerships  (and each of the
Partnerships as defined in the Prime  Facility):  (a) is a general  partnership,
limited  partnership  or  limited  liability  company,   as  appropriate,   duly
organized,  validly  existing,  and in  good  standing  under  the  laws  of the
jurisdiction  of its  formation;  (b) has all  requisite  partnership  power and
authority or company power and authority, as appropriate,  to own its assets and
carry on its  business as now being or as proposed to be  conducted;  and (c) is
qualified  to do  business  in all  jurisdictions  in which  the  nature  of its
business  makes such  qualification  necessary  and where  failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Borrower, or any Guarantor.


<PAGE>


         Section  7.2  Financial  Statements.  Borrower  has  delivered  to  the
Administrative Agent audited consolidated  financial statements of Prime Medical
as  of  and  for  the  fiscal  year  ended  December  31,  1998,  and  unaudited
consolidated financial statements of Prime Medical for the nine (9) month period
ended  September  30, 1999.  Such  financial  statements  have been  prepared in
accordance with GAAP, and fairly present, on a consolidated basis, the financial
condition of Prime  Medical and its  Subsidiaries,  as of the  respective  dates
indicated  therein  and the results of  operations  for the  respective  periods
indicated  therein.  There has been no material  adverse change in the business,
condition (financial or otherwise),  operations,  or properties of the Companies
(as defined in the Prime  Facility)  taken as a whole or Prime Medical since the
effective  date of the most  recent  financial  statements  referred  to in this
Section.

         Section 7.3 Corporate Action: No Breach. The execution,  delivery,  and
performance  by each Company and each  Guarantor of this Agreement and the other
Loan  Documents  to which such Company or Guarantor is or may become a party and
compliance  with the terms and  provisions  hereof  and  thereof  have been duly
authorized by all requisite  corporate  action (or, if such Company or Guarantor
is a  partnership,  then  partnership  action)  on the part of such  Company  or
Guarantor  and do not and will not (a) violate or conflict  with, or result in a
breach of, or require any consent  under (i) the  articles of  incorporation  or
bylaws of such  Company or  Guarantor  (or, if such  Company or  Guarantor  is a
partnership,  then the partnership agreement of such Company or Guarantor), (ii)
any material  applicable law, rule, or regulation or any material  order,  writ,
injunction,  or decree of any Governmental Authority or arbitrator, or (iii) any
material  agreement or  instrument to which such Company or Guarantor is a party
or by which such Company or Guarantor or any of its property is bound or subject
(other than agreements and  instruments  relating to Debt which will be paid off
with the proceeds of the initial Advance),  or (b) constitute a material default
under any such agreement or instrument  (other than  agreements and  instruments
relating  to Debt  which  will be paid  off  with the  proceeds  of the  initial
Advance),  or  result in the  creation  or  imposition  of any Lien  (except  as
provided  in  Article  V)  upon  any of the  revenues  or  assets  of any of the
Companies or any Guarantor.

         Section 7.4  Operation  of  Business.  Each of the  Companies  and each
Guarantor  possesses all licenses,  permits,  franchises,  patents,  copyrights,
trademarks,  and  tradenames,  or rights  thereto,  necessary  to conduct  their
respective  businesses  substantially as now conducted and as presently proposed
to be  conducted.  None of the  Companies or  Guarantors  is in violation of any
valid rights of others with respect to any of the  foregoing  (except  where the
failure  to do so would not have a  material  adverse  effect  on the  business,
condition  (financial or  otherwise),  operations or properties of the Companies
taken as a whole, Borrower, or any Guarantor.)

         Section 7.5 Litigation and Judgments.  As of the date hereof, except as
disclosed on Schedule 7.5 hereto,  there is no action, suit,  investigation,  or
proceeding before or by any Governmental  Authority or arbitrator pending, or to
the knowledge of Borrower,  threatened against or affecting any of the Companies
or any Guarantor,  that would, if adversely determined,  have a material adverse
effect on the  business,  condition  (financial  or  otherwise),  operations  or
properties of the Companies taken as a whole or Borrower,  or any Guarantor,  or
the  ability  of  Borrower  to pay and  perform  the  Obligations.  There are no
outstanding judgments against any Company.

         Section 7.6 Rights in Properties; Liens. Each of the Companies and each
Guarantor has good and  indefeasible  title to or valid  leasehold  interests in
their respective material  properties and assets,  real and personal,  including
the  properties,  assets,  and  leasehold  interests  reflected in the financial
statements  described  in Section 7.2, and none of the  properties,  assets,  or
leasehold  interests of any Company is subject to any Lien,  except as permitted
by Section 9.2.


<PAGE>


         Section 7.7 Enforceability.  This Agreement constitutes,  and the other
Loan Documents to which Borrower is a party,  when delivered,  shall  constitute
the legal,  valid,  and binding  obligations  of Borrower,  enforceable  against
Borrower  in  accordance  with  their  respective  terms,  except as  limited by
bankruptcy,  insolvency,  or other laws of general  application  relating to the
enforcement of creditors'  rights. The Loan Documents to which each Guarantor is
a party,  when  delivered,  shall  constitute  the  legal,  valid,  and  binding
obligations of such Guarantor,  enforceable against such Guarantor in accordance
with their respective  terms,  except as limited by bankruptcy,  insolvency,  or
other laws of general  application  relating to the  enforcement  of  creditors'
rights.

         Section 7.8 Approvals.  No authorization,  approval, or consent of, and
no filing or registration with, any Governmental  Authority or third party is or
will be necessary for the execution, delivery, or performance by Borrower or any
Guarantor of this  Agreement and the other Loan  Documents to which  Borrower or
any  Guarantor  is or may become a party or for the  validity or  enforceability
thereof.

     Section 7.9 Debt. As of the date hereof,  the Companies and the  Guarantors
have no Debt, except as disclosed on Schedule 7.9.

         Section 7.10 Taxes.  The  Companies  and the  Guarantors  have filed or
extended  all tax  returns  (federal,  state,  and local)  required to be filed,
including all income,  franchise,  employment,  property, and sales tax returns,
and have  paid all of  their  respective  liabilities  for  taxes,  assessments,
governmental  charges,  and other  levies  that are due and  payable  other than
certain  state tax returns  required  to be filed on or before the date  hereof.
Except as  previously  disclosed  to the  Administrative  Agent in  writing,  no
Company nor any Guarantor knows of any pending  investigation  of any of them by
any taxing  authority or of any pending but  unassessed  tax liability of any of
them.

         Section 7.11 Use of  Proceeds;  Margin  Securities.  No Company nor any
Guarantor is engaged principally,  or as one of its important activities, in the
business of extending  credit for the purpose of purchasing  or carrying  margin
stock (within the meaning of Regulations T, U, or X of the Board of Governors of
the Federal Reserve System),  and no part of the proceeds of any Advance will be
used to purchase or carry any margin stock or to extend credit to others for the
purpose  of  purchasing  or  carrying  margin  stock,  except for  purchases  of
Borrower's capital stock permitted by Section 9.4 hereof.

         Section 7.12 ERISA.  The Companies and the Guarantors are in compliance
in all material  respects with all  applicable  provisions  of ERISA.  Neither a
Reportable  Event nor a Prohibited  Transaction  has occurred and is  continuing
with  respect  to any Plan.  No notice  of intent to  terminate  a Plan has been
filed, nor has any Plan been terminated. No circumstances exist which constitute
grounds entitling the PBGC to institute  proceedings to terminate,  or appoint a
trustee to administer, a Plan, nor has the PBGC instituted any such proceedings.
None of the  Companies,  Guarantors  nor any ERISA  Affiliate has  completely or
partially  withdrawn from a Multi-employer  Plan. The Companies,  Guarantors and
each ERISA  Affiliate have met their minimum  funding  requirements  under ERISA
with respect to all of their Plans, and the present value of all vested benefits
under  each  Plan  does not  exceed  the fair  market  value of all Plan  assets
allocable to such benefits, as determined on the most recent valuation,  date of
the  Plan  and in  accordance  with  ERISA.  None  of  the  Companies,  nor  any
Guarantors, nor any ERISA Affiliate has incurred any liability to the PBGC under
ERISA.


<PAGE>


         Section 7.13  Disclosure.  All factual  information  (taken as a whole)
furnished  by or on behalf of Borrower or any  Guarantor in writing to any Agent
or any Lender (including,  without limitation, all factual information contained
in the Loan Documents) for purposes of or in connection with this Agreement, the
other Loan Documents or any transaction  contemplated  herein or therein is, and
all other such factual  information (taken as a whole) hereafter furnished by or
on behalf of Borrower or any  Guarantor in writing will be, true and accurate in
all material respects on the date as of which such factual  information is dated
or  certified  and is not  (and  such  factual  information  (taken  as a whole)
hereafter  furnished  will not be)  incomplete  by  omitting  to state any facts
necessary to make such factual  information (taken as a whole) not misleading in
any material respect at such time in light of the circumstances under which such
factual information was provided.

         Section 7.14  Subsidiaries;  Partnerships.  The Partnerships  listed on
Schedule 3, constitute all of the Subsidiaries of Prime Medical or Borrower,  as
the case may be. Schedule  7.14.1,  as the same may be amended from time to time
to reflect transactions permitted by this Agreement,  sets forth the outstanding
shares of  capital  stock (or other  ownership  interests)  and the name of each
shareholder  of each of the  Subsidiaries  of Prime Medical or Borrower,  as the
case may be. All of the  outstanding  capital  stock of Borrower and each of its
Subsidiaries  and Prime  Medical and each of its  Subsidiaries  has been validly
issued, is fully paid, and is nonassessable. Schedule 7.14.2, as the same may be
amended from time to time to reflect  transactions  permitted by this Agreement,
sets forth the outstanding  partnership  interests of the Partnerships  owned by
each of the Companies and Guarantors.

         Section 7.15 Agreements. None of the Companies or Guarantors is a party
to any indenture,  loan, or credit agreement, or to any lease or other agreement
or instrument,  or subject to any charter or corporate  restriction  which could
reasonably  be  expected  to have a  material  adverse  effect on the  business,
condition  (financial or  otherwise),  operations or properties of the Companies
taken as a whole,  Borrower or any  Guarantor  or the ability of Borrower or any
Guarantor to pay and perform its  obligations  under the Loan Documents to which
it is a party. None of the Companies or Guarantors is in default in any material
respect  in  the  performance,   observance,   or  fulfillment  of  any  of  the
obligations,  covenants,  or conditions contained in any agreement or instrument
to which it is a party,  which  default,  in the  aggregate  with all such other
defaults,  would  have a  material  adverse  affect on the  business,  condition
(financial or otherwise),  operations or properties of the Companies  taken as a
whole, Borrower, or any Guarantor.

     Section   7.16   Compliance   with   Legal    Requirements;    Governmental
Authorizations.

         (a)  Except as set  forth in  Schedule  7.16.1:  (i) each  Company  and
Guarantor is in compliance in all material  respects with each Legal Requirement
that is or was  applicable  to it or to the conduct or operation of its business
or the  ownership or use of any of its assets;  and (ii) no Company or Guarantor
has received any notice or other  communication from any Governmental  Authority
or other Person of any event or circumstance  which could constitute a violation
of, or failure to comply with, any Legal Requirement.


<PAGE>


         (b)  Except  as set  forth  in  Schedule  7.16:  (i) each  Company  and
Guarantor is in material  compliance  with all of the terms and  requirements of
each  Governmental  Authorization  held by such  Company or  Guarantor;  (ii) no
Company or Guarantor  has received  any notice or other  communication  from any
Governmental Authority or other Person of, any event or circumstance which could
constitute a violation of, or failure to comply with, any term or requirement of
any  Governmental  Authorization,  or of any  actual  or  potential  revocation,
withdrawal,  cancellation  or termination of, or material  modification  to, any
Governmental  Authorization;  (iii) all applications required to have been filed
for the renewal of any required Governmental Authorizations have been duly filed
on a timely basis with the appropriate Governmental  Authorities,  and all other
filings   required  to  have  been  made  with  respect  to  such   Governmental
Authorizations  have  been  duly  made on a timely  basis  with the  appropriate
Governmental Authorities;  (iv) all Governmental Authorizations of the Companies
and  Guarantors  are  transferable  to the  Companies and  Guarantors;  (v) upon
consummation  of  the  transactions   contemplated  hereby,  the  Companies  and
Guarantors  will lawfully hold all such  Governmental  Authorizations;  and (vi)
none of such Governmental Authorizations will terminate upon consummation of the
transactions  contemplated hereby. Except as set forth on Schedule 7.16, each of
the Companies and Guarantors possesses the necessary Governmental Authorizations
(i)  necessary  to permit each  Company and  Guarantor  to lawfully  conduct and
operate its respective business in the manner it currently conducts and operates
such  business and to permit such Company or Guarantor to own and use its assets
in the  manner  in  which it  currently  owns and  uses  such  assets,  and (ii)
necessary to permit each Company and  Guarantor,  upon the  consummation  of the
transactions  contemplated  hereby, to lawfully conduct and operate its business
and to permit each Company and  Guarantor  to own and use its assets,  where the
failure to have such  Governmental  Authorization  would have a material adverse
effect on the  business,  condition  (financial  or  otherwise),  operations  or
properties of the Companies taken as a whole, Borrower, or any Guarantor.

     Section  7.17  Investment  Company  Act.  No  Company  or  Guarantor  is an
"investment  company" within the meaning of the Investment  Company Act of 1940,
as amended.

         Section  7.18  Public  Utility  Holding  Company  Act.  No  Company  or
Guarantor  is a  "holding  company"  or a  "subsidiary  company"  of a  "holding
company" or an "affiliate" of a "holding  company" or a "public  utility" within
the meaning of the Public Utility Holding Company Act of 1935, as amended.

     Section 7.19 Environmental  Matters.  Except as disclosed on Schedule 7.19,
as the same may be amended from time to time, hereto:

         (a)  Each  of the  Companies  and  each  Guarantor  and  all  of  their
respective properties,  assets, and operations are in compliance in all material
respects with all  Environmental  Laws. No Company or Guarantor is aware of, nor
have any of them received notice of, any past,  present,  or future  conditions,
events, activities,  practices, or incidents which may interfere with or prevent
the material  compliance  or  continued  material  compliance  of any Company or
Guarantor with all material Environmental Laws; and

         (b) The Companies and  Guarantors  have obtained all material  permits,
licenses and  authorizations  that are required under  applicable  Environmental
Laws,  and all such  permits  are in good  standing  and each  Company  and each
Guarantor is in  compliance  is all material  respects with all of the terms and
conditions of such permits.

         Section 7.20 Year 2000 Compliance. Borrower represents that it is aware
of the possible impact of the year 2000 problem (that is, the risk that computer
applications may not be able to properly perform date-sensitive  functions after
December  31,  1999)  upon its  computer  applications  and  on-going  business.
Borrower  represents that any corrective action necessary will be taken and that
the year 2000  problem  will not  result  in a  material  adverse  change in the
Companies'  and  Guarantors'   business  condition   (financial  or  otherwise),
operations, properties or prospects, or ability to repay the Obligations.


<PAGE>


                       ARTICLE VIII -- POSITIVE COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe each of the following positive covenants:

     Section  8.1   Reporting   Requirements.   Borrower  will  furnish  to  the
Administrative Agent and each Lender:

         (a) Annual Financial Statements. As soon as available, and in any event
within ninety-five (95) days after the end of each fiscal year of Prime Medical,
beginning  with the fiscal year ending  December  31, 1999, a copy of the annual
audit  report of the Prime  Companies  for such  fiscal  year  containing,  on a
consolidated basis, balance sheets and statements of income,  retained earnings,
and cash flow as at the end of such  fiscal  year and for the twelve  (12)-month
period then ended,  in each case setting forth in  comparative  form the figures
for  the  preceding  fiscal  year,  audited  by  independent   certified  public
accountants  of  recognized  standing,  and  accompanied  by an  opinion of such
independent  certified  public  accountants  stating  that such  report has been
prepared in accordance with GAAP;

         (b) Monthly  Financial  Statements.  As soon as  available,  and in any
event  within forty (40) days after the end of each month of each fiscal year of
Borrower, a copy of an unaudited financial report of the Companies and the Prime
Companies  as of the end of such month and for the  portion  of the fiscal  year
then ended,  containing,  on a consolidated basis, balance sheets and statements
of income and retained earnings,  in each case setting forth in comparative form
the figures for the corresponding period of the preceding fiscal year, certified
by the chief  financial  officer of Borrower to have been prepared in accordance
with GAAP and to fairly  and  accurately  present  (subject  to  year-end  audit
adjustments) the financial condition and results of operations of the Companies,
on a consolidated basis, at the date and for the periods indicated therein;

         (c) Quarterly Financial  Statements.  As soon as available,  and in any
event within  forty-five  (45) days after the end of each quarter of each fiscal
year of Borrower,  a copy of an unaudited  financial report of the Companies and
the Prime  Companies  and of Prime RVC as of the end of such quarter and for the
portion of the fiscal  year then ended,  containing,  on a  consolidated  basis,
balance sheets and statements of income,  retained  earnings,  and cash flow, in
each case setting forth in  comparative  form the figures for the  corresponding
period of the preceding fiscal year, certified by the chief financial officer or
treasurer  of Borrower  to have been  prepared  in  accordance  with GAAP and to
fairly and  accurately  present  (subject to  year-end  audit  adjustments)  the
financial  condition  and results of  operations  of the Companies and the Prime
Companies  and  Prime  RVC and  its  Subsidiaries,  as the  case  may  be,  on a
consolidated  basis, at the date and for the periods  indicated  therein,  and a
copy of an  unaudited  financial  report of the  Companies as of the end of such
quarter  beginning  with the fiscal  quarter  ending  March 31, 2000 and for the
portion  of the  fiscal  year then  ended,  containing,  on a  consolidated  and
consolidating basis, balance sheets and statements of income, retained earnings,
and cash flow,  in each case setting forth in  comparative  form the figures for
the  corresponding  period of the preceding fiscal year,  certified by the chief
financial  officer of Borrower to have been prepared in accordance with GAAP and
to fairly and accurately  present  (subject to year-end audit  adjustments)  the
financial condition and results of operations of the Companies,  as the case may
be, on a consolidated and  consolidating  basis, at the date and for the periods
indicated therein;


<PAGE>


         (d) Compliance  Certificate.  Concurrently with the delivery of each of
the financial  statements  referred to in Section  8.1(a) and within  forty-five
(45) days after the end of each of the first  three (3) fiscal  quarters of each
fiscal year of Borrower, a certificate of the chief executive or chief financial
officer or treasurer of Borrower,  in  substantially  the form of Exhibit F, (i)
stating  that to such  officer's  knowledge,  no  Default  has  occurred  and is
continuing,  or if a Default has occurred and is  continuing,  a statement as to
the nature  thereof and the action  that is  proposed  to be taken with  respect
thereto,  and (ii) showing in reasonable  detail the calculations  demonstrating
compliance with Article X;

         (e) Accounts  Receivable Aging Report.  As soon as available and in any
event within forty (40) days after the end of each month, an aged listing of the
accounts  receivable  of each of  Borrower  and its  Subsidiaries  and of  Prime
Medical  and  each of its  Subsidiaries  as of the end of such  month  in a form
reasonably satisfactory to the Administrative Agent;

         (f) Business Plan and Budget.  As soon as available and in any event by
January 15 of the then current  year,  a copy of the annual  budget and business
plan of  Borrower  and its  Subsidiaries  and of Prime  Medical  and each of its
Subsidiaries  for  the  upcoming  fiscal  year,  together  with  details  of the
assumptions, if any, underlying such budget and business plan;

     (g)  Management  Letters.  Promptly  upon  receipt  thereof,  a copy of any
management letter or written report submitted to any Company or any Guarantor by
independent certified public accountants with respect to the business, condition
(financial or otherwise), operations, or properties of any Company;

         (h) Notice of  Litigation.  Promptly  after the  commencement  thereof,
notice of all actions,  suits, and proceedings before any Governmental Authority
or arbitrator  affecting Borrower or any of its Subsidiaries or any of the Prime
Companies  which,  if  determined  adversely to Borrower,  Guarantor or any such
Subsidiary,  could have a material  adverse  effect on the  business,  condition
(financial or otherwise),  options,  or properties of Borrower,  any Subsidiary,
the Companies, or the Prime Companies (taken as a whole);

         (i) Notice of Default. As soon as possible and in any event within five
(5) days after  Borrower  knows of the  occurrence  of each  Default,  a written
notice  setting  forth the details of such Default and the action that  Borrower
has taken and proposes to take with respect thereto;

         (j) ERISA Reports. Promptly after the filing or receipt thereof, copies
of all reports, including annual reports, and notices which any Company or Prime
Company  files with or receives  from the PBGC or the U.S.  Department  of Labor
under ERISA; and as soon as possible and in any event within five (5) days after
any  Company or Prime  Company  knows or has reason to know that any  Reportable
Event or  Prohibited  Transaction  has occurred with respect to any Plan or that
the PBGC,  or any Company or Prime  Company  has  instituted  or will  institute
proceedings  under Title IV of ERISA to terminate any Plan, a certificate of the
chief  financial  officer  of  Borrower  setting  forth the  details  as to such
Reportable  Event or Prohibited  Transaction or Plan  termination and the action
that Borrower proposes to take with respect thereto;

         (k) Reports to Other Creditors.  Promptly after the furnishing thereof,
copies  of  any  statement  or  report  furnished  by  Borrower  or  any  of its
Subsidiaries  or any Guarantor to any other creditor to which any Company or any
Guarantor  owes  $250,000.00  or  more  or  to  the  trustee  under  the  Senior
Subordinated Indenture (as defined in the Prime Facility), pursuant to the terms
of any  indenture,  loan,  or  credit or  similar  agreement  and not  otherwise
required to be furnished to the Administrative Agent and the Lenders pursuant to
any other clause of this Section;


<PAGE>


         (l) Proxy Statements,  Etc. As soon as available,  one (1) copy of each
financial statement,  report, notice or proxy statement sent by Prime Medical to
its stockholders generally and one (1) copy of each regular, periodic or special
report,  registration  statement,  or prospectus filed by Prime Medical with any
securities  exchange or the Securities and Exchange  Commission or any successor
agency including, without limitation, all Forms 10-K, 10-Q and 8-K and all other
periodic reports required to be filed under the Securities  Exchange Act of 1934
and the rules and regulations promulgated thereunder;

         (m)  Partnership  Lists.  As soon as  available,  and in any  event (a)
within thirty (30) days after the Administrative Agent requests such information
from  Borrower,  a list of the names and  addresses of each partner or member of
each of the  Partnerships  and  percentage  ownership  by each  Company  of each
Partnership;

         (n) Governmental Authorizations. Upon the request of the Administrative
Agent, but not more often than one (1) time during each fiscal year of Borrower,
a complete and accurate list of each Governmental  Authorization held by each of
Companies or Prime Companies or that otherwise  relate to the business of, or to
any of the assets owned or used by, each of the  Companies and each of the Prime
Companies;

         (o) Dilution  Reports.  Promptly upon the  occurrence of any Restricted
Transfer (as  hereinafter  defined),  a report  setting forth the  occurrence of
Restricted Transfer, including the name of the Partnership, purchasers, purchase
price,   and  EBITDA  for  the   immediately   preceding  four  fiscal  quarters
attributable  thereto, and also of the contribution of any Partnership assets to
any  other  Partnership,   including  the  names  of  the  Partnerships,  assets
transferred, value thereof and consideration received;

         (p) Partnership Actions.  Promptly after the incurrence thereof, notice
of any Partnership's (i) incurrence of Debt, (ii) change in accounting treatment
or reporting practices (which change shall not affect any reporting requirements
set  forth  herein  or the Loan  Documents),  except  as  permitted  by GAAP and
disclosed to the Administrative  Agent, (iii) change in tax reporting treatment,
except  as  permitted  by law,  (iv)  amendment  of any  partnership  agreement,
regulations,  or management  agreement  between such Partnership and any Company
and copies of any such  amendment  certified  by an officer of Borrower as being
true and correct, and (v) change in its insurance; and

     (q)  General  Information.  Promptly,  such  other  information  concerning
Borrower or any of its  Subsidiaries as the  Administrative  Agent or any Lender
may from time to time reasonably request.

         Section 8.2  Maintenance  of Existence;  Conduct of Business.  Borrower
will  preserve  and  maintain  its  corporate  existence  and all of its leases,
privileges, licenses, permits, franchises,  qualifications,  and rights that are
necessary or desirable in the ordinary  conduct of its  business.  Borrower will
cause  each  of its  Subsidiaries,  to  preserve  and  maintain  its  corporate,
partnership  or  other  similar  existence  and all of its  leases,  privileges,
licenses, permits,  franchises,  qualifications and rights that are necessary or
desirable in the ordinary conduct of its business,  except,  in each case, where
failure  to do so would not have a  material  adverse  effect  on the  business,
condition  (financial or  otherwise),  operations or properties of the Companies
taken as a whole,  Borrower,  or any Guarantor.  Borrower will conduct, and will
cause each of its  Subsidiaries  to  conduct,  its  business  in an orderly  and
efficient manner in accordance with good business practices.


<PAGE>


         Section 8.3  Maintenance of Properties.  Borrower will maintain,  keep,
and  preserve,  and  cause  each of its  Subsidiaries  to  maintain,  keep,  and
preserve, all of its properties (tangible and intangible) necessary or useful in
the proper conduct of its business in good working order and condition,  except,
in each case,  as  permitted by Section 9.8 or 9.9 or where the failure to do so
would not have a material adverse effect on the business,  condition  (financial
or  otherwise),  operations or  properties  of the  Companies  taken as a whole,
Borrower, or any Guarantor.

         Section 8.4 Taxes and Claims. Borrower will pay or discharge,  and will
cause each of its Subsidiaries other than the Excepted  Subsidiaries,  to pay or
discharge,  at or before maturity or before becoming delinquent (a) all material
taxes, levies, assessments, and governmental charges imposed on it or its income
or profits or any of its material  property,  and (b) all material lawful claims
for labor,  material,  and supplies,  which, if unpaid, might become a Lien upon
any of its property; provided, however, that no Company shall be required to pay
or discharge any tax, levy,  assessment,  or governmental  charge which is being
contested in good faith by appropriate  proceedings  diligently pursued, and for
which adequate reserves have been established.

         Section 8.5 Insurance.  Borrower will maintain,  and will cause each of
its Subsidiaries to maintain (except in the case of the  Partnerships,  in which
case Borrower shall maintain for the  Partnerships),  insurance with financially
sound and reputable  insurance companies in such amounts and covering such risks
as is usually carried by corporations  engaged in similar  businesses and owning
similar  properties in the same general  areas in which the  Companies  operate,
consistent  with past practices of the Companies and to the extent  available on
commercially reasonable terms, provided that in any event Borrower will maintain
and cause each of its Subsidiaries  (except in the case of the Partnerships,  in
which case Borrower shall maintain for the  Partnerships) to maintain  workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance, professional liability insurance, and business interruption insurance
reasonably   satisfactory  to  the  Lenders.   Each  insurance  policy  covering
Collateral shall name the Administrative Agent as loss payee, for the benefit of
the Lenders, as its interests may appear and shall provide that such policy will
not be canceled or reduced without thirty (30) days' prior written notice to the
Administrative  Agent.  Borrower will annually provide the Administrative  Agent
with all  certificates  of  insurance  evidencing  all  policies of insurance of
Borrower and its Subsidiaries.

         Section 8.6 Inspection  Rights. At any reasonable time and from time to
time after reasonable notice to Borrower,  Borrower will permit,  and will cause
each of its Subsidiaries to permit,  representatives of the Administrative Agent
and each Lender to examine,  copy, and make extracts from its books and records,
to visit and inspect its  properties,  and to discuss its business,  operations,
and financial  condition with its officers,  and  independent  certified  public
accountants.  Prior to removing  any such  copies or  extracts  from a Company's
premises,  such  Company's   representatives  shall  be  provided  a  reasonable
opportunity to review such information and mark or identify it as "confidential"
or "confidential information" as reasonably deemed appropriate by such Company.

         Section 8.7 Keeping Books and Records. Borrower will maintain, and will
cause each of its  Subsidiaries to maintain,  proper books of record and account
in which full,  true, and correct  entries in conformity with GAAP shall be made
of all dealings and transactions in relation to its business and activities.

         Section 8.8 Compliance with Laws.  Borrower will comply, and will cause
each of its Subsidiaries to comply,  in all material  respects with all material
applicable laws,  rules,  regulations,  orders,  and decrees of any Governmental
Authority or arbitrator.


<PAGE>


         Section 8.9 Compliance with Agreements.  Borrower will comply, and will
cause each of its  Subsidiaries  to comply,  in all material  respects  with all
agreements, contracts, and instruments binding on it or affecting its properties
or business, except where the failure to do so would not have a material adverse
effect on the  business,  condition  (financial  or  otherwise),  operations  or
properties of the Companies taken as a whole, Borrower, or any Guarantor.

         Section 8.10 Further Assurances. Borrower will (a), and will cause each
of its Subsidiaries  (other than the  Partnerships) to, execute and deliver such
further  agreements  and  instruments  and take  such  further  action as may be
reasonably requested by the Administrative Agent to carry out the provisions and
purposes of this  Agreement and the other Loan Documents and, (b) and will cause
each of its Subsidiaries (including the Partnerships) to, create,  preserve, and
perfect the Liens of the  Administrative  Agent, for the benefit of the Lenders,
in the Collateral.

         Section 8.11 ERISA.  Borrower  will comply,  and will cause each of its
Subsidiaries  to comply,  with all minimum funding  requirements,  and all other
material  requirements,  of ERISA, if applicable,  so as not to give rise to any
liability thereunder.

         Section 8.12 Information  Relating to Proposed  Acquisitions.  Borrower
will use its best  efforts  to keep the  Administrative  Agent  and the  Lenders
informed  of the  relevant  information  and  status of and will  share with the
Administrative  Agent and the Lenders and provide copies to the extent possible,
of all material due diligence  information  relating to any proposed Acquisition
with respect to which Borrower or any Subsidiary  enters into a letter of intent
or acquisition agreement, during the term of this Agreement.

         Section  8.13  After-Acquired   Subsidiaries.   Concurrently  upon  the
formation  or  Acquisition  by Borrower  or any  Guarantor  of any  Wholly-Owned
Subsidiary  after  the date  hereof  (pursuant  to a  Permitted  Acquisition  or
otherwise)   (an   "After-Acquired   Subsidiary"),   Borrower  shall  cause  the
After-Acquired  Subsidiary to deliver  articles of  incorporation,  bylaws,  and
resolutions (or other corresponding  constituent documents) and such opinions as
the  Administrative  Agent shall  require  and to execute a Guaranty,  Guarantor
Security Agreement,  and Pledge Agreement (if applicable),  as shall be required
by the  Administrative  Agent to  create  first  priority  Liens in favor of the
Administrative  Agent,  for the benefit of the Lenders,  in such  After-Acquired
Subsidiary's assets, to secure the Obligations.

         Section 8.14 Syndication  Cooperation.  Borrower  acknowledges that the
Agents intend  promptly to commence to syndicate the  Commitments of the Lenders
in accordance  with the provisions of Section 13.6.  Borrower agrees to actively
assist  Agents  and  their   Affiliates  in  achieving  a  syndication  that  is
satisfactory  to Agents and Borrower and in preparing  information  requested by
Agents in connection  with arranging and  syndication of the  Commitments of the
Lenders  and to take  such  other  action  deemed  necessary  by Agents or their
Affiliates,  including  the  holding  of a formal  presentation  to  prospective
Lenders to achieve a successful  syndication of the  Commitments by Agents.  The
syndication  efforts will be accomplished  by a variety of means,  including the
preparation  of  a  confidential  information  memorandum  and  other  marketing
materials,  direct contact  during the  syndication  between  senior  management
(including, but not limited to, the chief executive officer, the chief financial
officer and treasurer of Borrower)  and advisors and  Affiliates of Borrower and
the proposed syndicate Lenders.


<PAGE>


                        ARTICLE IX -- NEGATIVE COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe the following negative covenants:

         Section 9.1 Debt. Borrower will not incur, create, assume, or permit to
exist,  nor permit any of its  Subsidiaries  (other  than the  Partnerships)  to
incur, create, assume, or permit to exist, any Debt, except:

     (a) Debt owed to the Agents and the Lenders pursuant to the Loan Documents;

(b) Existing Debt described on Schedule 7.9 hereto;

         (c)      Debt owed to Borrower or to any Wholly-Owned Subsidiary;

     (d) Debt in an aggregate  principal  amount not to exceed  $4,000,000.00 at
any time outstanding the proceeds of which are used by the Companies to purchase
equipment;

     (e) Any Company's  obligations as general  partner of a Partnership for the
Debt of such Partnership;

     (f) Any Company's Guarantee of Debt of any Partnership,  if such Company is
a general partner of such Partnership;

         (g)      Subordinated Debt; and

         (h)      Any Financial Hedge.

         Section  9.2  Limitation  on Liens.  Borrower  will not incur,  create,
assume,  or permit to exist, nor permit any of its Subsidiaries  (other than the
Partnerships) to incur, create, assume, or permit to exist, any Lien upon any of
their respective properties, assets, or revenues, whether now owned or hereafter
acquired, except:

         (a)      Liens disclosed on Schedule 9.2;

         (b)      Liens securing Debt permitted by Section 9.1(d);

     (c) Liens in favor of the  Administrative  Agent,  for the  benefit  of the
Lenders or the counter-party under any Financial Hedge;

     (d) Liens securing Debt permitted by Section 9.1(g), which are subordinated
to the Liens described in Section 9.2(c);

     (e) Liens securing the Prime Facility,  which are subordinated to the Liens
described in Section 9.2(c);


<PAGE>


         (f) Encumbrances consisting of minor easements, zoning restrictions, or
other  restrictions on the use of real property that do not  (individually or in
the aggregate)  materially affect the value of the assets encumbered  thereby or
materially impair the ability of Borrower or any of its Subsidiaries to use such
assets in their  respective  businesses,  and none of which is  violated  in any
material respect by existing or proposed structures or land use;

         (g) Liens for taxes,  assessments,  or other governmental charges which
are not  delinquent  or which are being  contested  in good  faith and for which
adequate reserves have been established;

     (h)  Liens of  mechanics,  materialmen,  warehousemen,  carriers,  or other
similar  statutory  Liens  securing  obligations  that  are  not yet due and are
incurred in the ordinary course of business; and

         (i) Liens  resulting  from good faith  deposits  to secure  payments of
workmen's  compensation  or other  social  security  programs  or to secure  the
performance of tenders,  statutory  obligations,  surety and appeal bonds, bids,
contracts  (other  than for  payment of Debt),  or leases  made in the  ordinary
course of business.

         Section 9.3 Mergers,  Etc. Except upon the prior written consent of the
Required  Lenders,  neither  Borrower nor any Guarantor will become a party to a
merger or  consolidation,  except in connection  with any  Permitted  Refractive
Acquisition so long as Borrower or a Guarantor is the surviving entity. Borrower
will  not,  and  will  not  permit  any  of its  Subsidiaries  (other  than  the
Partnerships)  to, wind-up,  dissolve or liquidate  itself,  except as permitted
above. Except as otherwise  permitted by this Agreement,  Borrower will not, and
will not permit any of its Subsidiaries to, form,  incorporate,  acquire or make
any investment in any Subsidiary, except (a) the Subsidiaries listed on Schedule
7.14.1,  (b)  Subsidiaries  acquired or formed  through a  Permitted  Refractive
Acquisition, and (c) Wholly-Owned Subsidiaries formed in accordance with Section
8.13.

         Section 9.4 Restricted  Payments.  Borrower will not declare or pay any
dividends or make any other payment or distribution  (whether in cash, property,
or obligations) on account of its capital stock, or redeem, purchase, retire, or
otherwise acquire any of its capital stock, or permit any of its Subsidiaries to
purchase or otherwise  acquire any capital  stock of Borrower,  or set apart any
money  for a  sinking  or  other  analogous  fund  for  any  dividend  or  other
distribution on its capital stock or for any redemption,  purchase,  retirement,
or other  acquisition of any of its capital stock.  Borrower shall not permit to
exist any  arrangement,  agreement,  or corporate  governance  agreement,  which
directly or indirectly  prohibits or restricts any Subsidiary  from declaring or
paying  any  dividend  or  distribution,   on  account  of  its  capital  stock,
partnership,  limited liability company, or other ownership interests;  provided
that to the  extent  permitted  by Section  2.3(c),  the  Partnerships  may make
Distributions to their respective partners not more often than quarterly limited
to an amount  sufficient  to pay such  partners'  federal  and state  income tax
liability   arising  from  their   partnership   interests  in  the   applicable
Partnerships.

         Section 9.5 Investments.  Borrower will not make, nor permit any of its
Subsidiaries  to make,  any  advance,  loan,  extension  of  credit,  or capital
contribution  to or  investment  in, or  purchase  or own,  or permit any of its
Subsidiaries to purchase or own, any stock, bonds, notes,  debentures,  or other
securities of, any Person, except:


<PAGE>


         (a) The Companies,  or any of them, may purchase (i) readily marketable
direct  obligations  of the United States of America or any agency  thereof with
maturities of one year or less from the date of acquisition,  (ii) fully insured
certificates  of deposit  with  maturities  of one year or less from the date of
acquisition  issued by any  commercial  bank  operating in the United  States of
America  having  capital  and  surplus  in excess of  $1,000,000,000,  and (iii)
commercial  paper of a domestic  issuer if at the time of purchase such paper is
rated in one (1) of the two (2) highest rating categories of Standard and Poor's
Rating  Group,  a division of McGraw  Hill,  Inc.,  a New York  corporation,  or
Moody's Investors Service, Inc.;

         (b) The Borrower and Guarantors may create new Subsidiaries, hold stock
in Subsidiaries  and  themselves,  and engage in the  transactions  permitted by
Section 9.3 hereof, provided that Borrower complies with Section 8.13;

         (c)      Permitted Refractive Acquisitions;

         (d)      Any Financial Hedge; and

     (e) Loans from Borrower to Prime Refractive,  L.L.C. in connection with any
Permitted  Refractive  Acquisition,  so long as such loans secure payment of the
Obligations and the "Obligations" under the Prime Facility.

         Section 9.6 Limitation on Issuance of Capital Stock.  Borrower will not
permit any of its Subsidiaries to at any time issue,  sell, assign, or otherwise
dispose of (a) any of its capital stock or other  ownership  interests,  (b) any
securities  exchangeable  for or  convertible  into or  carrying  any  rights to
acquire  any of its  capital  stock or  other  ownership  interests,  or (c) any
option,  warrant,  or other right to acquire  any of its capital  stock or other
ownership  interests;  provided,  however,  that any  Subsidiary of Borrower may
issue, sell, assign or otherwise dispose of its capital stock or other ownership
interests,  or securities  exchangeable for its capital stock or other ownership
interests, to Borrower or any other Wholly-Owned Subsidiary.

         Section 9.7 Transactions With Affiliates. Borrower will not enter into,
and will not permit any of its  Subsidiaries  to enter  into,  any  transaction,
including,  without limitation,  the purchase,  sale, or exchange of property or
the rendering of any service,  with any Affiliate of Borrower or any  Subsidiary
of Borrower,  except in the ordinary  course of Borrower's or such  Subsidiary's
business  and upon fair and  reasonable  terms no less  favorable to Borrower or
such Subsidiary than would be obtained in a comparable arm's-length  transaction
with a Person not an Affiliate of Borrower or such Subsidiary.  No Company shall
make any loan,  advance,  investment,  or  transfer  any assets to any  Excepted
Subsidiary,  so long as such Excepted  Subsidiary is not in good standing  where
incorporated.


<PAGE>


         Section  9.8  Disposition  of Assets.  Borrower  will not sell,  lease,
assign,  transfer,  or otherwise dispose of any of its assets, nor permit any of
its  Subsidiaries  (other  than  the  Partnerships)  to do so with  any of their
respective  assets,  except  (subject to the mandatory  prepayments  required by
Section 2.3) (a)  inter-Company  transfers  between  Borrower and a Wholly-Owned
Subsidiary  or  between  Wholly-Owned  Subsidiaries,  (b)  dispositions  of  any
tangible  assets that are worn or obsolete,  provided that such tangible  assets
are replaced by assets of similar  character where the replacement of such asset
is necessary or appropriate for the continued conduct of such Company's business
as presently  conducted,  and (g) transfers by Borrower or by any  Subsidiary of
interests in  Partnerships,  so long as the  aggregate  EBITDA  Transfer for all
Restricted  Transfers  does not exceed the lesser of : (a) ten percent  (10%) of
Borrower's  EBITDA for the most  recently  ended four fiscal  quarters,  and (b)
$2,000,000.  "EBITDA Transfer" with respect to any Partnership  interests in any
Partnership  transferred by Borrower or by any Subsidiary shall equal the EBITDA
generated by such Partnership  interests for the last four fiscal quarters prior
to the date of such  transfer of each such  Partnership  interest.  A Restricted
Transfer  shall be any transfer or series of related  transfers  of  Partnership
interests in any one  Partnership  by Borrower or any  Subsidiary  in any 90 day
period, in which the EBITDA Transfer equals or exceeds $250,000.  In the case of
any transfers  pursuant to paragraph (g), after giving effect to such transfers,
a Company must own at least 51% of the equity  interests in such Partnership and
Control such  Partnership.  Administrative  Agent is  authorized  to release any
liens on such Partnership interests transferred pursuant to this Section 9.8, as
further set forth in Section 5.3.

         Section  9.9 Sale and  Leaseback.  Borrower  will not enter  into,  nor
permit any of its Subsidiaries  (other than the Partnerships) to enter into, any
arrangement  with any Person (other than another  Company)  pursuant to which it
leases from such Person equipment used in refractive  vision operations that has
been or is to be sold or  transferred,  directly  or  indirectly,  by it to such
Person.

     Section 9.10 Prepayment of Debt.  Borrower will not prepay,  nor permit any
of its Subsidiaries to prepay, any Debt except the Obligations.

         Section 9.11 Nature of Business. Borrower will not, and will not permit
any of its Subsidiaries (other than the Partnerships) to, engage in any business
other  than  correcting  refractive  error of the eye or  businesses  which  are
reasonably related thereto.

         Section 9.12 Environmental Protection.  Borrower will not, and will not
permit any of its  Subsidiaries  to,  conduct  any  activity or use any of their
respective  properties or assets in any manner that could reasonably be expected
to violate any  Environmental  Law or create any  Environmental  Liabilities for
which Borrower or any of its Subsidiaries would be responsible.

         Section 9.13 Accounting.  Borrower will not, and will not permit any of
its  Subsidiaries  (other than the  Partnerships)  to, change its fiscal year or
make any change (a) in accounting  treatment or reporting  practices,  except as
permitted  by GAAP and  disclosed  to the  Administrative  Agent,  or (b) in tax
reporting treatment, except as permitted by law.

         Section  9.14  Amendment  of  Partnership  and  Management  Agreements.
Borrower  will not,  and will not permit any of its  Subsidiaries  to, amend any
partnership agreements,  regulations,  or articles of any of the Partnerships or
any management  agreements  between any Company and any of the Partnerships,  if
such amendment could reasonably be expected to have a material adverse effect on
the business,  condition (financial or otherwise),  operations, or properties of
the Companies taken as a whole, Borrower, or any Guarantor.

         Section 9.15      Financial Hedges.

         (a) To the extent any Lender or its Affiliate  issues a Financial Hedge
to any  Company,  such Lender or its  Affiliate is afforded the benefits of (and
Borrower [or any Company by execution of Collateral Documents] hereby confirms a
grant  of)  Liens  in and to  the  Collateral  as  evidenced  by the  Collateral
Documents  to the  extent  of such  Lender's  (or  Affiliate  thereof's)  credit
exposure  under  such  Financial  Hedge;  such Lien is pari  passu  with that of
Administrative Agent on behalf of the Lenders.


<PAGE>


         (b)  Financial  Hedges  held  by any  Company  permitted  by  the  Loan
Documents,  shall be subject  to the  following:  (i) each such  Lender or other
institution  issuing a Financial  Hedge shall calculate its credit exposure in a
reasonable and customary manner; (ii) all documentation for such Financial Hedge
shall conform to ISDA standards and must be acceptable to  Administrative  Agent
with  respect  to  intercreditor  issues;  (iii) if issued by any  Lender or any
Affiliate  of a Lender to Borrower,  the credit  exposure  under such  Financial
Hedge shall be secured by Liens in and to the  Collateral  as  evidenced  by the
Collateral  Documents  on a pari passu  basis  with the Liens of  Administrative
Agent (held for the benefit of Lenders),  and such Lender or Affiliate issuing a
Financial  Hedge  shall,  by  acceptance  of the  benefits  of such Liens in the
Collateral  agree to the  provisions  of Section 12.6;  and (iv) such  Financial
Hedge shall be incurred in the ordinary  course of business and consistent  with
prior business practices of the Companies and not for speculative purposes.

         Section  9.16  Capital  Expenditures.  Borrower  shall not make Capital
Expenditures in any fiscal year exceeding $500,000. Such limitation set forth in
this Section shall not apply to any of Borrower's Subsidiaries or Partnerships.

         Section  9.17  Operating  Expenses.  Borrower  shall  not  incur or pay
operating expenses in any fiscal year in excess of $200,000. Such limitation set
forth in this  Section  shall not  apply to any of  Borrower's  Subsidiaries  or
Partnerships.

     Section 9.18 Control of Prime Refractive,  L.L.C. Borrower shall own 51% of
the membership interests in and Control Prime Refractive, L.L.C.


                                          ARTICLE X  --  FINANCIAL COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe the following financial covenants:

         Section  10.1 Senior  Funded Debt To EBITDA  Ratio.  Borrower  will not
permit  the Senior  Net Debt to EBITDA  Ratio as of the last day of each  fiscal
quarter of Borrower to exceed the ratio set forth opposite such dates below:

            Period                                            Ratio

Date hereof through December 31, 2000                      2.50 to 1.0

January 1, 2002 and thereafter                             2.00 to 1.0

         Section 10.2 Debt Service Coverage Ratio.  Borrower will not permit the
Debt  Service  Coverage  Ratio  as of the  last day of each  fiscal  quarter  of
Borrower to be less than the ratio set forth opposite such dates below:


             Period                                            Ratio

Date hereof through December 31, 2000                      1.50 to 1.0

January 1, 2002 and thereafter                             1.75 to 1.0




<PAGE>


                              ARTICLE XI -- DEFAULT

Section 11.1 Events of Default.  Each of the following shall be deemed an "Event
of Default":

     (a) Borrower  shall fail to pay when due any amount of principal  under any
Note.

         (b)  Borrower  shall  fail to pay to the  Administrative  Agent  or any
Lender (through the  Administrative  Agent),  any interest on the Advances,  any
fees due  hereunder or under any other Loan  Document,  or any other part of the
Obligations  which  does not  constitute  principal  under the  Notes,  and such
failure  shall  continue for three (3) Business  Days after such payment  became
due.

         (c) Any  representation  or warranty made or deemed made by Borrower or
any Obligated Party (or any of their  respective  officers) in any Loan Document
or in any certificate,  report,  notice, or financial statement furnished at any
time in connection with this Agreement shall be false, misleading,  or erroneous
in any  material  respect  when made or deemed to have been made and the  effect
thereof  shall not have been cured  within ten (10)  Business  Days after notice
thereof to  Borrower  by the  Administrative  Agent or any Lender  (through  the
Administrative Agent).

         (d)  Borrower  shall  fail to  perform,  observe,  or  comply  with any
covenant,  agreement,  or  term  contained  in  Article  X; or  Borrower  or any
Obligated  Party shall fail to perform,  observe,  or comply with any  covenant,
agreement or term  contained in Section 8.1 (a),  (b), (c) or (d), or Article IX
and such failure  shall  continue for a period of three (3) Business  Days after
notice thereof to Borrower by the  Administrative  Agent or any Lender  (through
the  Administrative  Agent);  or Borrower or any  Obligated  Party shall fail to
perform, observe or comply with any other covenant, agreement, or term contained
in this  Agreement or any other Loan Document  (other than  covenants to pay the
Obligations)  and such failure shall  continue for a period of ten (10) Business
Days after notice thereof to Borrower by the Administrative  Agent or any Lender
(through the Administrative Agent).

         (e)  Any  Company  shall  commence  a  voluntary   proceeding   seeking
liquidation, reorganization, or other relief with respect to itself or its debts
under any  bankruptcy,  insolvency,  or other  similar law now or  hereafter  in
effect or seeking the appointment of a trustee, receiver, liquidator, custodian,
or other similar  official of it or a substantial  part of its property or shall
consent to any such relief or to the appointment of or taking  possession by any
such official in an involuntary case or other proceeding commenced against it or
shall make a general  assignment for the benefit of creditors or shall generally
fail to pay its debts as they become due or shall take any  corporate  action to
authorize any of the foregoing.

         (f) An involuntary  proceeding  shall be commenced  against any Company
seeking liquidation,  reorganization,  or other relief with respect to it or its
debts under any bankruptcy, insolvency, or other similar law now or hereafter in
effect or seeking the appointment of a trustee, receiver, liquidator,  custodian
or other  similar  official for it or a substantial  part of its  property,  and
either such involuntary  proceeding shall remain  undismissed and unstayed for a
period of forty-five (45) days or an order for relief is entered.

         (g) Any Company  shall fail to discharge  within a period of forty-five
(45) days after the  commencement  thereof  any  attachment,  sequestration,  or
similar  proceeding or proceedings,  including  without  limitation any order of
forfeiture,  seizure or divestiture  (whether under RICO or otherwise) involving
an  aggregate  amount in excess of Five  Hundred  Thousand  and  00/100  Dollars
($500,000.00) against any of its assets or properties.


<PAGE>


         (h) A final judgment or judgments for the payment of money in excess of
Five Hundred Thousand and 00/100 Dollars ($500,000.00) in the aggregate shall be
rendered  by a court or courts  against  any  Company  and the same shall not be
discharged  (or provision  shall not be made for such  discharge),  or a stay of
execution  thereof shall not be procured,  within  forty-five (45) days from the
date of entry  thereof  and such  Company  shall  not,  within  said  period  of
forty-five  (45) days, or such longer period during which  execution of the same
shall have been stayed,  appeal therefrom and cause the execution  thereof to be
stayed during such appeal.

         (i) Any Company shall fail to pay when due any principal of or interest
on the Subordinated  Debt or on any other Debt in an aggregate  principal amount
of Five Hundred  Thousand and 00/100 Dollars  ($500,000.00)  or more (other than
the Obligations  and the Prime  Facility),  or the maturity of the  Subordinated
Debt  or any  such  Debt  (other  than  the  Prime  Facility)  shall  have  been
accelerated,  or the  Subordinated  Debt or any such Debt  (other than the Prime
Facility)  shall have been required to be prepaid  prior to the stated  maturity
thereof,  or any event shall have  occurred that permits (or, with the giving of
notice or the lapse of time or both,  would permit) any holder or holders of the
Subordinated  Debt or such Debt  (other than the Prime  Facility)  or any Person
acting on behalf of such holder or holders to accelerate the maturity thereof or
require any such prepayment.

         (j) This Agreement or any other Loan Document shall cease to be in full
force  and  effect  or  shall be  declared  null  and  void or the  validity  or
enforceability  thereof  shall be  contested  or  challenged  by  Borrower,  any
Subsidiary  of  Borrower,  any  Obligated  Party  or  any  of  their  respective
shareholders,  or  Borrower  or any  Obligated  Party shall deny that it has any
further liability or obligation under any of the Loan Documents,  or any Lien or
security interest created by the Loan Documents shall for any reason cease to be
a valid,  first priority perfected security interest in and Lien upon any of the
Collateral purported to be covered thereby.

         (k) Any of the  following  events  shall occur or exist with respect to
Borrower,  any Guarantor or any ERISA Affiliate:  (i) any Prohibited Transaction
involving any Plan;  (ii) any Reportable  Event with respect to any Plan;  (iii)
the filing under  Section  4041 of ERISA of a notice of intent to terminate  any
Plan or the termination of any Plan;  (iv) any event or circumstance  that might
constitute  grounds  entitling the PBGC to institute  proceedings  under Section
4042 of ERISA for the  termination  of, or for the  appointment  of a trustee to
administer, any Plan, or the institution by the PBGC of any such proceedings; or
(v) complete or partial  withdrawal  under  Section 4201 or 4204 of ERISA from a
Multi-employer  Plan or the  reorganization,  insolvency,  or termination of any
Multi-employer  Plan; and in each case above, such event or condition,  together
with all other  events or  conditions,  if any,  have  subjected or could in the
reasonable  opinion of the  Required  Lenders  subject  Borrower,  or any of its
Subsidiaries,  or any Guarantor,  to any tax,  penalty,  or other liability to a
Plan, a Multi-employer Plan, the PBGC, or otherwise (or any combination thereof)
which in the  aggregate  exceed or could  reasonably  be expected to exceed Five
Hundred Thousand and 00/100 Dollars ($500,000.00).

         (l)      Any Change in Control shall occur.

         Section  11.2  Remedies.  If any Event of  Default  shall  occur and be
continuing,  the  Administrative  Agent  may (and if  directed  by the  Required
Lenders, shall) do any one or more of the following:


<PAGE>


                  (a)  Acceleration.  Declare all  outstanding  principal of and
         accrued and unpaid  interest on the Notes and all other  obligations of
         Borrower under the Loan Documents  immediately due and payable, and the
         same  shall  thereupon  become  immediately  due and  payable,  without
         notice,   demand,   presentment,   notice   of   dishonor,   notice  of
         acceleration,  notice  of  intent  to  accelerate,  protest,  or  other
         formalities  of any kind, all of which are hereby  expressly  waived by
         Borrower;

     (b) Termination of Commitments. Terminate the Commitments without notice to
Borrower;
                  (c)      Judgment.  Reduce any claim to judgment;

     (d)  Foreclosure.  Foreclose or  otherwise  enforce any Lien granted to the
Administrative Agent for the benefit of itself and the Lenders to secure payment
and  performance  of the  Obligations  in accordance  with the terms of the Loan
Documents; and

     (e) Rights.  Exercise any and all rights and remedies  afforded by the laws
of the State of Texas or any other  jurisdiction,  by any of the Loan Documents,
by equity, or otherwise;

provided,  however,  that  upon the  occurrence  of an Event  of  Default  under
subsection  (e) or (f) of Section 11.1,  the  Commitments  of all of the Lenders
shall automatically  terminate, and the outstanding principal of and accrued and
unpaid  interest on the Notes and all other  obligations  of Borrower  under the
Loan  Documents  shall  thereupon  become  immediately  due and payable  without
notice, demand, presentment, notice of dishonor, notice of acceleration,  notice
of intent to accelerate, protest, or other formalities of any kind, all of which
are hereby expressly waived by Borrower.

         Section 11.3 Performance by the Administrative Agent. If Borrower shall
fail to perform any covenant or agreement  in  accordance  with the terms of the
Loan Documents,  the Administrative  Agent may, at the direction of the Required
Lenders,  perform or attempt to perform such  covenant or agreement on behalf of
Borrower.  In such event,  Borrower shall, at the request of the  Administrative
Agent,  promptly  pay any amount  expended  by the  Administrative  Agent or the
Lenders in connection  with such  performance  or attempted  performance  to the
Administrative Agent at the Principal Office,  together with interest thereon at
the  Default  Rate  from  and  including  the  date of such  expenditure  to but
excluding  the  date  such  expenditure  is paid in  full.  Notwithstanding  the
foregoing,  it is expressly agreed that neither the Administrative Agent nor any
Lender shall have any liability or  responsibility  for the  performance  of any
obligation of Borrower under this Agreement or any of the other Loan Documents.

                     ARTICLE XII -- THE ADMINISTRATIVE AGENT

         Section 12.1 Appointment,  Powers and Immunities.  In order to expedite
the various  transactions  contemplated  by this  agreement,  the Lenders hereby
irrevocably appoint and authorize Bank of America to act as their Administrative
Agent  hereunder  and under  each of the other Loan  Documents.  Bank of America
consents  to  such   appointment  and  agrees  to  perform  the  duties  of  the
Administrative  Agent as specified herein.  The Lenders authorize and direct the
Administrative Agent to take such action in their name and on their behalf under
the terms and  provisions of the Loan  Documents and to exercise such rights and
powers  thereunder  as  are  specifically   delegated  to  or  required  of  the
Administrative  Agent for the Lenders,  together  with such rights and powers as
are reasonably  incidental thereto. The Administrative Agent is hereby expressly
authorized to act as the Administrative  Agent on behalf of itself and the other
Lenders:


<PAGE>


                  (a) To receive on behalf of each of the Lenders any payment of
         principal,  interest,  fees or  other  amounts  paid  pursuant  to this
         Agreement  and the Notes and to  distribute to each Lender its pro rata
         share of all payments so received as provided in this Agreement;

               (b) To receive all documents and items to be furnished  under the
          Loan Documents; (c) To act as nominee for and on behalf of the Lenders
          in and under the Loan Documents;

               (d) To arrange for the means whereby the funds of the Lenders are
          to be made available to Borrower;

                  (e)  To  distribute  to  the  Lenders  information,  requests,
         notices, payments, prepayments, documents and other items received from
         Borrower, the other Obligated Parties, and other Persons;

                  (f) To execute and deliver to  Borrower,  the other  Obligated
         Parties, and other Persons, all requests, demands, approvals,  notices,
         and consents received from the Lenders;

               (g) To the extent permitted by the Loan Documents, to exercise on
          behalf of each Lender all rights and  remedies of the Lenders upon the
          occurrence of any Event of Default;

                  (h) To accept,  execute,  and  deliver the  Borrower  Security
         Agreement,  the Guarantor Security  Agreements,  the Pledge Agreements,
         and any other security documents as the secured party; and

               (i) To  take  such  other  actions  as may  be  requested  by the
          Required Lenders.


<PAGE>


         Neither the Administrative  Agent nor any of its Affiliates,  officers,
directors, employees, attorneys, or agents shall be liable to any Lender for any
action  taken or omitted to be taken by any of them  hereunder  or  otherwise in
connection with this Agreement or any of the other Loan Documents (INCLUDING ANY
ACTION TAKEN OR OMITTED TO BE TAKEN BY SUCH PARTIES NEGLIGENTLY),  but excluding
such actions or omissions  arising from such  parties' own gross  negligence  or
willful  misconduct.  Without limiting the generality of the preceding sentence,
the  Administrative  Agent:  (i) may treat  the payee of any Note as the  holder
thereof until the Administrative Agent receives written notice of the assignment
or  transfer  thereof  signed  by such  payee  and in form  satisfactory  to the
Administrative Agent; (ii) shall have no duties or responsibilities except those
expressly set forth in this  Agreement and the other Loan  Documents,  and shall
not by reason of this  Agreement  or any other  Loan  Document  be a trustee  or
fiduciary for any Lender; (iii) shall not be required to initiate any litigation
or collection  proceedings  hereunder or under any other Loan Document except to
the extent requested by the Required  Lenders;  (iv) shall not be responsible to
the  Lenders  for  any  recitals,  statements,   representations  or  warranties
contained in this  Agreement or any other Loan Document,  or any  certificate or
other document referred to or provided for in, or received by any of them under,
this  Agreement  or any  other  Loan  Document,  or  for  the  value,  validity,
effectiveness,  enforceability,  or  sufficiency  of this Agreement or any other
Loan  Document  or any other  document  referred  to or  provided  for herein or
therein  or for any  failure by any  Person to  perform  any of its  obligations
hereunder or thereunder;  (v) may consult with legal counsel  (including counsel
for Borrower),  independent public accountants, and other experts selected by it
and shall not be liable  for any  action  taken or  omitted  to be taken in good
faith by it in  accordance  with the  advice of such  counsel,  accountants,  or
experts;  and (vi)  shall  incur no  liability  under or in  respect of any Loan
Document by acting upon any notice, consent, certificate, or other instrument or
writing  believed by it to be genuine and signed or sent by the proper  party or
parties.  As to any matters not expressly  provided for by this  Agreement,  the
Administrative  Agent  shall in all cases be fully  protected  in acting,  or in
refraining from acting, here under in accordance with instructions signed by the
Required  Lenders,  and such instructions of the Required Lenders and any action
taken or failure to act pursuant thereto shall be binding on all of the Lenders;
provided,  however,  that the Administrative Agent shall not be required to take
any action which exposes the Administrative Agent to personal liability or which
is contrary to this Agreement or any other Loan Document or applicable law.

         Section 12.2 Rights of Administrative  Agent as a Lender.  With respect
to its  Commitment,  the Advances  made by it and the Note issued to it, Bank of
America in its  capacity  as a Lender  hereunder  shall have the same rights and
powers hereunder as any other Lender and may exercise the same as though it were
not acting as the  Administrative  Agent,  and the term  "Lender"  or  "Lenders"
shall, unless the context otherwise indicates,  include the Administrative Agent
in its  individual  capacity.  The  Administrative  Agent and its Affiliates may
(without  having to account  therefor to any Lender) accept  deposits from, lend
money to, act as trustee under  indentures of, provide merchant banking services
to, and generally  engage in any kind of business with Borrower,  any Subsidiary
of Borrower, any other Obligated Party, and any other Person who may do business
with or own securities of Borrower or any other  Obligated  Party,  all as if it
were not  acting as the  Administrative  Agent and  without  any duty to account
therefor to the Lenders.

         Section 12.3  Sharing of Payments,  Etc. If any Lender shall obtain any
payment of any  principal  of or interest  on any Advance  made by it under this
Agreement or payment of any other  obligation under the Loan Documents then owed
by Borrower or any other  Obligated  Party to such  Lender,  whether  voluntary,
involuntary,  through  the  exercise  of any  right of  setoff,  lender's  lien,
counterclaim  or similar right,  or otherwise,  in excess of its pro rata share,
such Lender shall promptly purchase from the other Lenders participations in the
Advances held by them hereunder in such amounts, and make such other adjustments
from time to time as shall be necessary to cause such purchasing Lender to share
the excess payment ratably with each of the other Lenders in accordance with its
pro rata portion thereof. To such end, all of the Lenders shall make appropriate
adjustments among themselves (by the resale of participations sold or otherwise)
if all or any portion of such excess  payment is  thereafter  rescinded  or must
otherwise be restored. Borrower agrees, to the fullest extent it may effectively
do so under applicable law, that any Lender so purchasing a participation in the
Advances made by the other  Lenders may exercise all rights of setoff,  lender's
lien,  counterclaim,  or similar  rights with respect to such  participation  as
fully as if such  Lender  were a direct  holder of  Advances  to Borrower in the
amount of such participation.  Nothing contained herein shall require any Lender
to exercise  any such right or shall affect the right of any Lender to exercise,
and retain the benefits of exercising,  any such right with respect to any other
indebtedness or obligation of Borrower.


<PAGE>


         Section 12.4 Indemnification. THE LENDERS HEREBY AGREE TO INDEMNIFY THE
AGENTS FROM AND HOLD THE AGENTS  HARMLESS  AGAINST (TO THE EXTENT NOT REIMBURSED
UNDER SECTIONS 13.1 AND 13.2, BUT WITHOUT  LIMITING THE  OBLIGATIONS OF BORROWER
UNDER  SECTIONS  13.1 AND 13.2),  RATABLY IN  ACCORDANCE  WITH THEIR  RESPECTIVE
COMMITMENTS, ANY AND ALL LIABILITIES,  OBLIGATIONS,  LOSSES, DAMAGES, PENALTIES,
ACTIONS, JUDGMENTS,  DEFICIENCIES,  SUITS, COSTS, EXPENSES (INCLUDING ATTORNEYS'
FEES), AND  DISBURSEMENTS OF ANY KIND OR NATURE  WHATSOEVER WHICH MAY BE IMPOSED
ON, INCURRED BY, OR ASSERTED AGAINST ANY AGENT IN ANY WAY RELATING TO OR ARISING
OUT OF ANY OF THE LOAN  DOCUMENTS  OR ANY ACTION TAKEN OR OMITTED TO BE TAKEN BY
ANY AGENT UNDER OR IN RESPECT OF ANY OF THE LOAN DOCUMENTS INCLUDING ANY PORTION
OF THE  FOREGOING TO THE EXTENT  CAUSED BY THE ANY AGENT'S SOLE OR  CONTRIBUTORY
NEGLIGENCE; PROVIDED, FURTHER, THAT NO LENDER SHALL BE LIABLE FOR ANY PORTION OF
THE FOREGOING TO THE EXTENT  CAUSED BY ANY AGENT'S  GROSS  NEGLIGENCE OR WILLFUL
MISCONDUCT.  WITHOUT LIMITATION OF THE FOREGOING, IT IS THE EXPRESS INTENTION OF
THE  LENDERS  THAT THE  AGENTS  SHALL  BE  INDEMNIFIED  HEREUNDER  FROM AND HELD
HARMLESS  AGAINST  ALL  OF  SUCH  LIABILITIES,   OBLIGATIONS,  LOSSES,  DAMAGES,
PENALTIES, ACTIONS, JUDGMENTS,  DEFICIENCIES,  SUITS, COSTS, EXPENSES (INCLUDING
ATTORNEYS' FEES), AND DISBURSEMENTS OF ANY KIND OR NATURE DIRECTLY OR INDIRECTLY
ARISING OUT OF OR  RESULTING  FROM THE SOLE OR  CONTRIBUTORY  NEGLIGENCE  OF THE
AGENTS. WITHOUT LIMITING ANY OTHER PROVISION OF THIS SECTION, EACH LENDER AGREES
TO REIMBURSE EACH AGENT PROMPTLY UPON DEMAND FOR ITS PRO RATA SHARE  (CALCULATED
ON THE  BASIS  OF  THE  COMMITMENTS)  OF  ANY  AND  ALL  OUT-OF-POCKET  EXPENSES
(INCLUDING  ATTORNEYS'  FEES)  INCURRED  BY THE  AGENTS IN  CONNECTION  WITH THE
PREPARATION,  EXECUTION, DELIVERY,  ADMINISTRATION,  MODIFICATION,  AMENDMENT OR
ENFORCEMENT (WHETHER THROUGH NEGOTIATIONS,  LEGAL PROCEEDINGS, OR OTHERWISE) OF,
OR LEGAL  ADVICE  IN  RESPECT  OF  RIGHTS OR  RESPONSIBILITIES  UNDER,  THE LOAN
DOCUMENTS,  TO THE EXTENT THAT SUCH AGENT IS NOT REIMBURSED FOR SUCH EXPENSES BY
BORROWER.

         Section 12.5 Independent  Credit Decisions.  Each Lender agrees that it
has  independently  and without  reliance on any Agent or any other Lender,  and
based on such documents and information as it has deemed  appropriate,  made its
own credit  analysis of Borrower and decision to enter into this  Agreement  and
that it will,  independently  and without  reliance  upon any Agent or any other
Lender,  and  based  upon  such  documents  and  information  as it  shall  deem
appropriate  at the time,  continue to make its own  analysis  and  decisions in
taking or not  taking  action  under  this  Agreement  or any of the other  Loan
Documents.  The  Administrative  Agent  shall  not be  required  to keep  itself
informed as to the  performance or observance by Borrower or any Obligated Party
of this  Agreement or any other Loan  Document or to inspect the  properties  or
books of Borrower or any Obligated Party. Except for notices,  reports and other
documents and information  expressly  required to be furnished to the Lenders by
the  Administrative  Agent  hereunder  or under the other  Loan  Documents,  the
Administrative  Agent shall not have any duty or  responsibility  to provide any
Lender with any credit or other  financial  information  concerning the affairs,
financial  condition or business of Borrower or any  Obligated  Party (or any of
their Affiliates) which may come into the possession of the Administrative Agent
or any of its Affiliates.

         Section 12.6 Several Commitments. The Commitments and other obligations
of the Lenders under this  Agreement  are several.  The default by any Lender in
making an Advance in accordance with its Commitment  shall not relieve the other
Lenders of their obligations  under this Agreement.  In the event of any default
by any  Lender  in  making  any  Advance,  each  nondefaulting  Lender  shall be
obligated  to make its Advance but shall not be  obligated to advance the amount
which the defaulting Lender was required to advance hereunder. In no event shall
any  Lender be  required  to advance  an amount or  amounts  which  shall in the
aggregate  exceed such Lender's  Commitment.  No Lender shall be responsible for
any act or omission of any other Lender.


<PAGE>


         Section 12.7 Successor Administrative Agent. Subject to the appointment
and  acceptance  of a  successor  Administrative  Agent as provided  below,  the
Administrative  Agent may  resign at any time by giving  notice  thereof  to the
Lenders and  Borrower  and the  Administrative  Agent may be removed at any time
with or without  cause by the Required  Lenders.  Upon any such  resignation  or
removal,  the  Required  Lenders  will  have the right to  appoint  a  successor
Administrative   Agent  from  among  the  remaining  Lenders.  If  no  successor
Administrative  Agent shall have been so appointed  by the Required  Lenders and
shall have accepted such appointment  within thirty (30) days after the retiring
Administrative  Agent's giving of notice of resignation or the Required Lenders'
removal of the retiring  Administrative Agent, then the retiring  Administrative
Agent may, on behalf of the Lenders,  appoint a successor  Administrative Agent,
which shall be a commercial  bank organized  under the laws of the United States
of America or any State  thereof and having  combined  capital and surplus of at
least  One  Billion  Dollars  ($1,000,000,000).   Upon  the  acceptance  of  its
appointment as successor  Administrative  Agent,  such successor  Administrative
Agent shall  thereupon  succeed to and become  vested  with all rights,  powers,
privileges,  immunities,  and duties of the resigning or removed  Administrative
Agent,  and the  resigning or removed  Administrative  Agent shall be discharged
from its  duties  and  obligations  under  this  Agreement  and the  other  Loan
Documents.   After  any  Administrative   Agent's   resignation  or  removal  as
Administrative  Agent,  the  provisions  of this  Article XII shall  continue in
effect for its benefit in respect of any actions taken or omitted to be taken by
it while it was the Administrative Agent.

         Section 12.8      Independent Contractor.

         (a) The relationship between each Agent and each of the Lenders is that
of an  independent  contractor.  The use of the term "Agent" is for  convenience
only  and  is  used  to  describe,  as a form  of  convention,  the  independent
contractual  relationship  between each Agent and each of the  Lenders.  Nothing
contained in this  Agreement or the other Loan  Documents  shall be construed to
create an agency,  trust or other fiduciary  relationship  between any Agent and
any of the Lenders.

         (b) As an independent  contractor  empowered by the Lenders to exercise
certain  rights and perform  certain duties and  responsibilities  hereunder and
under the other Loan  Documents,  the  Administrative  Agent is  nevertheless  a
"representative"  of the  Lenders,  as that term is  defined in Article 1 of the
Uniform  Commercial Code, for purposes of actions for the benefit of the Lenders
and the  Administrative  Agent  with  respect  to all  collateral  security  and
guaranties  contemplated  by  the  Loan  Documents.  Such  actions  include  the
designation of the Administration  Agent as "secured party,"  "mortgagee" or the
like on all financing  statements and other documents and  instruments,  whether
recorded or  otherwise,  relating  to the  attachment,  perfection,  priority or
enforcement of any security interests, mortgages or deeds of trust in collateral
security   intended  to  secure  the  payment  or  performance  of  any  of  the
Obligations, all for the benefit of the Lenders and the Administrative Agent.

                          ARTICLE XIII -- MISCELLANEOUS


<PAGE>


         Section 13.1 Expenses. Borrower hereby agrees to pay on demand: (a) all
reasonable  costs and expenses of the Agents in connection with the preparation,
negotiation,  syndication,  execution,  and delivery of this  Agreement  and the
other  Loan  Documents  including,   without  limitation,  the  legal  fees  and
reasonable  expenses of legal counsel for the Agents;  (b) all reasonable  costs
and  expenses  of  the  Agents  in  connection  with  any  and  all  amendments,
modifications,   renewals,  extensions  and  supplements  of  any  of  the  Loan
Documents;  (c) all reasonable  costs and expenses of the Agents and the Lenders
in connection with any Default, including any work-outs,  amendments to any Loan
Documents,  or  negotiations  related  thereto,  and  the  enforcement  of  this
Agreement or any other Loan Document,  including,  without limitation,  the fees
and expenses of legal counsel and  professional  advisors for the Agents and the
Lenders;  (d)  all  transfer,  stamp,  documentary,   or  other  similar  taxes,
assessments,  or charges levied by any Governmental Authority in respect of this
Agreement  or any  of  the  other  Loan  Documents;  (e)  all  costs,  expenses,
assessments,   and  other  charges  incurred  in  connection  with  any  filing,
registration,  recording,  or  perfection  of  any  security  interest  or  Lien
contemplated  by this  Agreement or any other Loan  Document;  and (f) all other
reasonable  costs and expenses  incurred by the Agents in  connection  with this
Agreement or any other Loan Document,  including, without limitation, all costs,
expenses,  and other charges incurred in connection with obtaining any mortgagee
title insurance policy,  survey, audit,  appraisal in respect of the Collateral,
and other out-of-pocket costs and expenses.

         Section 13.2  Indemnification.  BORROWER SHALL INDEMNIFY THE AGENTS AND
EACH LENDER AND EACH AFFILIATE THEREOF AND THEIR RESPECTIVE OFFICERS, DIRECTORS,
EMPLOYEES,  ATTORNEYS,  AND AGENTS FROM, AND HOLD EACH OF THEM HARMLESS AGAINST,
ANY  AND  ALL  LOSSES,  LIABILITIES,   CLAIMS,  DAMAGES,  PENALTIES,  JUDGMENTS,
DISBURSEMENTS,  COSTS, AND EXPENSES  (INCLUDING  REASONABLE  ATTORNEYS' FEES) TO
WHICH ANY OF THEM MAY BECOME SUBJECT WHICH DIRECTLY OR INDIRECTLY  ARISE FROM OR
RELATE TO (A) THE NEGOTIATION, EXECUTION, DELIVERY, PERFORMANCE, ADMINISTRATION,
OR  ENFORCEMENT  OF ANY OF  THE  LOAN  DOCUMENTS,  (B)  ANY OF THE  TRANSACTIONS
CONTEMPLATED  BY  THE  LOAN  DOCUMENTS,  (C)  ANY  BREACH  BY  BORROWER  OF  ANY
REPRESENTATION,  WARRANTY,  COVENANT, OR OTHER AGREEMENT CONTAINED IN ANY OF THE
LOAN  DOCUMENTS,  (D)  THE  PRESENCE,  RELEASE,  THREATENED  RELEASE,  DISPOSAL,
REMOVAL,  OR CLEANUP OF ANY HAZARDOUS  MATERIAL  LOCATED ON, ABOUT,  WITHIN,  OR
AFFECTING  ANY OF THE  PROPERTIES  OR ASSETS OF  BORROWER OR ANY  SUBSIDIARY  OF
BORROWER, OR (E) ANY INVESTIGATION,  LITIGATION, OR OTHER PROCEEDING, INCLUDING,
WITHOUT  LIMITATION,   ANY  THREATENED   INVESTIGATION,   LITIGATION,  OR  OTHER
PROCEEDING  RELATING TO ANY OF THE  FOREGOING.  WITHOUT  LIMITING THE FOREGOING,
THIS INDEMNITY SHALL APPLY TO ANY LOSS, LIABILITY,  OBLIGATION, DAMAGE, PENALTY,
JUDGMENT,  CLAIM,  DEFICIENCY  OR EXPENSE  ARISING OUT OF THE SOLE OR CONCURRENT
NEGLIGENCE  OF ANY AGENT OR ANY  LENDER,  BUT AS TO ANY  AGENT OR  LENDER  SHALL
EXCLUDE ANY LOSS,  LIABILITY,  OBLIGATION,  DAMAGE,  PENALTY,  JUDGMENT,  CLAIM,
DEFICIENCY  OR  EXPENSE  ARISING  BY REASON OF THE GROSS  NEGLIGENCE  OR WILLFUL
MISCONDUCT OF SUCH AGENT OR LENDER.

         Section 13.3 No Duty. All attorneys, accountants, appraisers, and other
professional  Persons  and  consultants  retained  by the Agents and the Lenders
shall have the right to act  exclusively  in the  interest of the Agents and the
Lenders and shall have no duty of disclosure,  duty of loyalty, duty of care, or
other duty or  obligation  of any type or nature  whatsoever  to  Borrower,  any
shareholder or Subsidiary of Borrower or any other Person.

         Section  13.4  No  Fiduciary  Relationship.  The  relationship  between
Borrower and each Lender is solely that of debtor and creditor,  and none of the
Agents nor any of the Lenders has any  fiduciary or other  special  relationship
with Borrower,  and no term or condition of any of the Loan  Documents  shall be
construed so as to deem the  relationship  between Borrower and any Lender to be
other than that of debtor and creditor.


<PAGE>


         Section 13.5 No Waiver;  Cumulative Remedies. No failure on the part of
the Agents or any Lender to exercise and no delay in  exercising,  and no course
of dealing with respect to, any right,  power, or privilege under this Agreement
shall operate as a waiver thereof,  nor shall any single or partial  exercise of
any right,  power,  or  privilege  under this  Agreement  preclude  any other or
further  exercise  thereof  or  the  exercise  of any  other  right,  power,  or
privilege.  The rights and remedies provided for in this Agreement and the other
Loan  Documents  are  cumulative  and not  exclusive  of any rights and remedies
provided by law.

         Section 13.6      Successors and Assigns.

         (a) This  Agreement  shall be binding  upon and inure to the benefit of
the parties hereto and their respective successors and assigns. Borrower may not
assign or transfer any of its rights or obligations  hereunder without the prior
written consent of the Administrative  Agent and all of the Lenders.  Any Lender
may sell  participations to one or more banks or other institutions in or to all
or a portion of its rights and  obligations  under this  Agreement and the other
Loan  Documents  (including,  without  limitation,  all  or  a  portion  of  its
Commitments  and the Advances  owing to it);  provided,  however,  that (i) such
Lender's   obligations  under  this  Agreement  and  the  other  Loan  Documents
(including,  without limitation,  its Commitments) shall remain unchanged,  (ii)
such Lender shall remain solely  responsible to Borrower for the  performance of
such obligations, (iii) such Lender shall remain the holder of its Notes for all
purposes of this  Agreement,  (iv)  Borrower  shall  continue to deal solely and
directly  with  such  Lender  in  connection   with  such  Lender's  rights  and
obligations  under this  Agreement  and the other Loan  Documents,  and (v) such
Lender shall not sell a participation  that conveys to the participant the right
to vote or give or  withhold  consents  under this  Agreement  or any other Loan
Document,  other than the right to vote upon or consent to (A) any  increase  of
such Lender's  Commitments,  (B) any  reduction of the  principal  amount of, or
interest to be paid on, the  Advances of such Lender,  (C) any  reduction of any
commitment  fee or other amount  payable to such Lender under any Loan Document,
or (D) any  postponement  of any date for the  payment of any amount  payable in
respect of the Advances of such Lender.

         (b)  Borrower  and  each of the  Lenders  agree  that  any  Lender  (an
"Assigning  Lender")  may at any time assign to one or more  Eligible  Assignees
all, or a portion of all, of its rights and obligations under this Agreement and
the other Loan  Documents  (including,  without  limitation,  its Commitment and
Advances) (each an "Assignee");  provided,  however, that (i) except in the case
of an  assignment  of  all of a  Lender's  rights  and  obligations  under  this
Agreement and the other Loan Documents,  or as otherwise  acceptable to Borrower
and the  Administrative  Agent the amount of the  Commitments  of the  assigning
Lender being assigned pursuant to each assignment  (determined as of the date of
the Assignment and Acceptance with respect to such assignment) shall in no event
be less than  $____________,  and (ii) the parties to each such assignment shall
execute and deliver to the Administrative Agent for its acceptance and recording
in the Register (as defined below), an Assignment and Acceptance,  together with
the Note subject to such  assignment,  and a processing and  recordation  fee of
$3,500.00. Upon such execution,  delivery,  acceptance,  and recording, from and
after the effective date  specified in each  Assignment  and  Acceptance,  which
effective  date shall be at least  five (5)  Business  Days after the  execution
thereof,  or, if so specified in such  Assignment  and  Acceptance,  the date of
acceptance  thereof by the  Administrative  Agent,  (x) the assignee  thereunder
shall be a party  hereto as a  "Lender"  and,  to the  extent  that  rights  and
obligations  hereunder have been assigned to it pursuant to such  Assignment and
Acceptance,  have the rights and obligations of a Lender hereunder and under the
Loan Documents and (y) the Lender that is an assignor  thereunder  shall, to the
extent that rights and  obligations  hereunder have been assigned by it pursuant
to such  Assignment and  Acceptance,  relinquish its rights and be released from
its  obligations  under this Agreement and the other Loan Documents (and, in the
case of an Assignment and Acceptance  covering all or the remaining portion of a
Lender's  rights and  obligations  under the Loan  Documents,  such Lender shall
cease to be a party  thereto).  The  provisions  of Article IV and Section  13.2
shall continue with respect to such Assigning Lender.


<PAGE>


         (c) By executing  and  delivering  an Assignment  and  Acceptance,  the
Assigning  Lender and its Assignee  confirm to and agree with each other and the
other parties hereto as follows:  (i) other than as provided in such  Assignment
and Acceptance,  such Assigning Lender makes no  representation  or warranty and
assumes  no  responsibility  with  respect  to any  statements,  warranties,  or
representations  made  in or in  connection  with  the  Loan  Documents  or  the
execution, legality, validity, and enforceability,  genuineness, sufficiency, or
value of the Loan  Documents  or any  other  instrument  or  document  furnished
pursuant thereto; (ii) such Assigning Lender makes no representation or warranty
and  assumes no  responsibility  with  respect  to the  financial  condition  of
Borrower or any Obligated  Party or the performance or observance by Borrower or
any  Obligated  Party of its  obligations  under the Loan  Documents;  (iii) the
Assignee  confirms that it has received copies of the Loan  Documents,  together
with  copies of the  financial  statements  referred  to in Section 7.2 and such
other  documents and  information  as it has deemed  appropriate to make its own
credit analysis and decision to enter into such Assignment and Acceptance;  (iv)
the Assignee will,  independently  and without reliance upon the  Administrative
Agent or such assignor and based on such  documents and  information as it shall
deem  appropriate  at the time,  continue  to make its own credit  decisions  in
taking or not taking action under this  Agreement and the other Loan  Documents;
(v) the Assignee  confirms  that it is an Eligible  Assignee;  (vi) the Assignee
appoints  and  authorizes  the  Administrative  Agent  to take  such  action  as
Administrative  Agent on its  behalf and  exercise  such  powers  under the Loan
Documents as are  delegated to the  Administrative  Agent by the terms  thereof,
together with such powers as are reasonably  incidental  thereto;  and (vii) the
Assignee  agrees that it will perform in accordance  with their terms all of the
obligations  which  by the  terms  of the  Loan  Documents  are  required  to be
performed by it as a Lender.

         (d) The  Administrative  Agent shall maintain at its Principal Office a
copy of each  Assignment  and  Acceptance  delivered to and accepted by it and a
register for the  recordation  of the names and addresses of the Lenders and the
Commitment  of, and principal  amount of the Advances owing to, each Lender from
time to time (the  "Register").  The entries in the Register shall be conclusive
and  binding  for  all  purposes,  absent  manifest  error,  and  Borrower,  the
Administrative  Agent,  and the  Lenders  may treat  each  Person  whose name is
recorded in the Register as a Lender  hereunder for all purposes  under the Loan
Documents.  The Register  shall be available  for  inspection by Borrower or any
Lender  at any  reasonable  time and from  time to time  upon  reasonable  prior
notice.

         (e) Upon its receipt of an  Assignment  and  Acceptance  executed by an
assigning Lender and Assignee  representing  that it is an Eligible Assignee (or
other  assignee  permitted  hereunder),  together  with any Note subject to such
assignment,  the  Administrative  Agent shall, if such Assignment and Acceptance
has been  completed  and is in  substantially  the form of Exhibit B, (i) accept
such Assignment and Acceptance, (ii) record the information contained therein in
the Register,  and (iii) give prompt written notice thereof to Borrower.  Within
five (5)  Business  Days after its  receipt  of such  notice,  Borrower,  at its
expense,  shall execute and deliver to the Administrative  Agent in exchange for
the surrendered Note a new Note to the order of such Eligible Assignee (or other
assignee  permitted  hereunder)  in an  amount  equal  to  the  portion  of  the
Commitments assumed by it pursuant to such Assignment and Acceptance and, if the
Assigning  Lender has retained a portion of the  Commitments,  a new Note to the
order  of  the  Assigning  Lender  in an  amount  equal  to the  portion  of the
Commitments retained by it hereunder (each such promissory note shall constitute
a "Note" for  purposes  of the Loan  Documents).  Such new Notes  shall be in an
aggregate principal amount of the surrendered Note, shall be dated the effective
date of such Assignment and Acceptance,  and shall otherwise be in substantially
the form of Exhibit C.


<PAGE>


         (f) Any Lender may, in connection with any assignment or  participation
or proposed  assignment or participation  pursuant to this Section,  disclose to
the Assignee or participant or proposed Assignee or participant, any information
relating to Borrower or any Subsidiary of Borrower  furnished to such, Lender by
or on behalf of Borrower or any of its Subsidiaries.

         (g)  Notwithstanding  any other term of this Agreement to the contrary,
any Lender may  (without  requesting  the  consent of either the  Administrative
Agent or  Borrower)  pledge  its Notes to a Federal  Reserve  Bank in support of
borrowings made by such Lender from such Federal Reserve Bank.

         (h)  Notwithstanding  any other term of this Agreement to the contrary,
any Lender may assign all,  or a portion of all,  of its rights and  obligations
under  this  Agreement  and  the  other  Loan  Documents   (including,   without
limitation,  its  Commitment and Advances) to an Affiliate of such Lender or any
other Lender provided that:

                  (i) such assignor  Lender has obtained the written  consent of
         the  Administrative  Agent  (which  consent  shall not be  unreasonably
         delayed or withheld)  if the effect of such  assignment  or  delegation
         shall entitle such Affiliate or other Lender to claim compensation from
         Borrower pursuant to Article IV; and

                  (ii) in every other case,  such assignor  Lender has furnished
         notice to, but not obtained the consent of, the Administrative Agent.

         Section 13.7 Survival.  All representations and warranties made in this
Agreement  or  any  other  Loan  Document  or in  any  document,  statement,  or
certificate  furnished  in  connection  with this  Agreement  shall  survive the
execution and delivery of this Agreement and the other Loan Documents  until the
Obligations  have been paid and performed in full, and no  investigation  by the
Administrative   Agent  or  any  Lender  or  any   closing   shall   affect  the
representations  and warranties or the right of the Administrative  Agent or any
Lender  to rely  upon  them.  Without  prejudice  to the  survival  of any other
obligation of Borrower  hereunder,  the obligations of Borrower under Article IV
and Sections 13.1 and 13.2 shall survive  repayment of the Notes and termination
of the Commitments.  The obligations of the Administrative Agent and the Lenders
under Section 13.18 shall survive  repayment of the Notes and termination of the
Commitments.

         Section 13.8 ENTIRE AGREEMENT. THIS AGREEMENT, THE NOTES, AND THE OTHER
LOAN DOCUMENTS  REFERRED TO HEREIN EMBODY THE FINAL,  ENTIRE AGREEMENT AMONG THE
PARTIES  HERETO  AND  SUPERSEDE  ANY  AND  ALL  PRIOR  COMMITMENTS,  AGREEMENTS,
REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER WRITTEN OR ORAL, RELATING TO THE
SUBJECT  MATTER  HEREOF AND MAY NOT BE  CONTRADICTED  OR VARIED BY  EVIDENCE  OF
PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT  ORAL  AGREEMENTS OR  DISCUSSIONS OF THE
PARTIES HERETO. THERE ARE NO ORAL AGREEMENTS AMONG THE PARTIES HERETO.


<PAGE>


         Section 13.9  Amendments,  Etc. No amendment or waiver of any provision
of this Agreement,  the Notes, or any other Loan Document to which Borrower is a
party,  nor any consent to any  departure  by Borrower  therefrom,  shall in any
event be  effective  unless  the same  shall be  agreed or  consented  to by the
Required  Lenders  and  Borrower,  and each  such  waiver  or  consent  shall be
effective only in the specific  instance and for the specific  purpose for which
given; provided, that no amendment,  waiver, or consent shall, unless in writing
and signed by all of the  Lenders and  Borrower,  do any of the  following:  (a)
increase  Commitments  of the Lenders or subject  the Lenders to any  additional
obligations;  (b) reduce the principal of, or interest on, the Notes or any fees
or other  amounts  payable to the Lenders,  (but not the  Administrative  Agent)
hereunder; (c) alter the allocation among Lenders of, or postpone any date fixed
for any payment or  prepayment  (whether or not  mandatory)  of principal of, or
interest  on,  the  Notes  or  any  fees  or  other   amounts   payable  to  the
Administrative Agent or the Lenders hereunder;  (d) change the percentage of the
Commitments  or of the  aggregate  unpaid  principal  amount of the Notes or the
number of Lenders which shall be required for the Lenders or any of them to take
any action  under this  Agreement;  (e) change any  provision  contained in this
Section 13.9; or (f) release any material  Guarantor or any material  portion of
the   Collateral,   except  in  accordance  with  the  relevant  Loan  Document.
Notwithstanding   anything  to  the  contrary  contained  in  this  Section,  no
amendment,  waiver, or consent shall be made with respect to Article XII without
the prior written consent of the Administrative Agent.

         Section  13.10  Maximum  Interest  Rate.  Regardless  of any  provision
contained  in any Loan  Document,  neither  Administrative  Agent nor any Lender
shall ever be entitled to contract  for,  charge,  take,  reserve,  receive,  or
apply, as interest on all or any part of the  Obligations,  any amount in excess
of the  Maximum  Rate,  and, if Lenders  ever do so,  then such excess  shall be
deemed a partial  prepayment of principal and treated  hereunder as such and any
remaining  excess shall be refunded to Borrower.  In determining if the interest
paid or payable  exceeds the Maximum Rate,  Borrower and Lenders  shall,  to the
maximum extent  permitted under  applicable Law, (a) treat all Advances as but a
single extension of credit (and Lenders and Borrower agree that such is the case
and that provision  herein for multiple  Advances is for convenience  only), (b)
characterize any nonprincipal payment as an expense, fee, or premium rather than
as interest,  (c) exclude voluntary prepayments and the effects thereof, and (d)
amortize,  prorate, allocate, and spread the total amount of interest throughout
the entire contemplated term of the Obligations. However, if the Obligations are
paid  and  performed  in full  prior to the end of the  full  contemplated  term
thereof, and if the interest received for the actual period of existence thereof
exceeds the Maximum  Amount,  Lenders  shall  refund such  excess,  and, in such
event,  Lenders  shall not,  to the extent  permitted  by Law, be subject to any
penalties provided by any laws for contracting for, charging, taking, reserving,
or receiving interest in excess of the Maximum Amount. The "Maximum Rate" or the
"Maximum  Amount,"  mean the "weekly  ceiling" from time to time in effect under
Texas Finance Code ss. 303.305, as amended.

         Section 13.11 Notices.  All notices and other  communications  provided
for in this  Agreement and the other Loan Documents to which Borrower is a party
shall be given or made by  telecopy  or in  writing  and  telecopied,  mailed by
certified mail return receipt requested,  or delivered to the intended recipient
at the "Address for Notices"  specified  below its name on the  signature  pages
hereof, or, as to any party at such other address as shall be designated by such
party in a notice to each other party  given in  accordance  with this  Section.
Except as otherwise provided in this Agreement, all such communications shall be
deemed to have  been  duly  given  when  transmitted  by  telecopy,  subject  to
telephone  confirmation of receipt, or when personally delivered or, in the case
of a mailed  notice,  when duly  deposited  in the mails,  in each case given or
addressed as aforesaid;  provided,  however, notices to the Administrative Agent
pursuant  to  Article  II  shall  not  be  effective   until   received  by  the
Administrative Agent.

         Section 13.12  Governing Law. THIS  AGREEMENT  SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.

         Section 13.13  Counterparts.  This  Agreement may be executed in one or
more counterparts,  each of which shall be deemed an original,  but all of which
together shall constitute one and the same instrument.


<PAGE>


         Section 13.14  Severability.  Any provision of this Agreement held by a
court of competent  jurisdiction to be invalid or unenforceable shall not impair
or invalidate  the remainder of this  Agreement and the effect  thereof shall be
confined to the provision held to be invalid or illegal.

     Section 13.15 Headings.  The headings,  captions,  and arrangements used in
this Agreement are for convenience only and shall not affect the  interpretation
of this Agreement.

         Section 13.16  Construction.  Borrower,  the Administrative  Agent, and
each Lender  acknowledges that each of them has had the benefit of legal counsel
of its own choice and has been afforded an  opportunity to review this Agreement
and the other Loan Documents with its legal counsel.

         Section 13.17 Independence of Covenants.  All covenants hereunder shall
be given  independent  effect so that if a particular action or condition is not
permitted  by any of such  covenants,  the fact that it would be permitted by an
exception to, or be otherwise  within the limitations of, another covenant shall
not avoid the  occurrence of a Default if such action is taken or such condition
exists.

         Section 13.18     Confidentiality.

         (a) The Agents and each Lender (each, a "Lending Party") agrees to keep
confidential  any Confidential  Information;  provided that nothing herein shall
prevent any Lending  Party from  disclosing  such  information  (a) to any other
Lending Party or any Affiliate of any Lending Party,  or any officer,  director,
employee, agent, or advisor of any Lending Party or any Affiliate of any Lending
Party, (b) to any other Person if reasonably incidental to the administration of
the credit  facility  provided  herein,  (c) as  required by any law,  rule,  or
regulation,  (d) upon the order of any court or administrative  agency, (e) upon
the request or demand of any regulatory  agency or authority,  (f) in connection
with any  litigation  to which  such  Lending  Party may be a party,  (g) to the
extent  necessary  in  connection  with the  exercise  of any remedy  under this
Agreement  or  any  other  Loan   Document,   and  (h)  subject  to   provisions
substantially  similar  to those  contained  in this  Section,  to any actual or
proposed   participant  or  Assignee.   Furthermore,   and  notwithstanding  the
foregoing,  no Lending Party shall provide any  Confidential  Information to any
officer,  director,  employee,  agent or advisor of any  Affiliate  of a Lending
Party if such officer, director,  employee, agent or advisor's position involves
the ability to transact  trades in, or solicit or accept orders for the purchase
or sale of, the common stock of Borrower.

         (b) The  Lending  Parties are aware that the United  States  securities
laws prohibit any Person who has received material,  non-public information such
as is the  subject of this  Section  13.18  from an issuer  from  purchasing  or
selling the securities of such issuer or from  communicating such information to
any other Person under circumstances in which it is reasonably  foreseeable that
such Person is likely to purchase or sell such securities.

         (c) The Companies and the Lending  Parties agree that monetary  damages
would not be a  sufficient  remedy for any breach of this  Section  13.18 by the
Lending Parties and that, in addition to all other remedies, the Companies shall
be entitled to specific  performance and injunction or other equitable relief as
a remedy for any such breach.

         (d) The  restrictions  and  obligations  of this  Section  13.18  shall
survive the repayment of the  Obligations and shall continue to bind the Lending
Parties.


<PAGE>


         Section 13.19 Waiver of Jury Trial. TO THE FULLEST EXTENT  PERMITTED BY
APPLICABLE LAW, BORROWER HEREBY  IRREVOCABLY AND EXPRESSLY WAIVES ALL RIGHT TO A
TRIAL BY JURY IN ANY ACTION,  PROCEEDING,  OR  COUNTERCLAIM  (WHETHER BASED UPON
CONTRACT,  TORT,  OR  OTHERWISE)  ARISING  OUT OF OR RELATING TO ANY OF THE LOAN
DOCUMENTS OR THE TRANSACTIONS  CONTEMPLATED  THEREBY OR THE ACTIONS OF ANY AGENT
OR ANY LENDER IN THE NEGOTIATION, ADMINISTRATION, OR ENFORCEMENT THEREOF.

         Section  13.20  Choice of Forum;  Consent to  Service  of  Process  and
Jurisdiction.  Any suit,  action or proceeding  against Borrower with respect to
this Agreement or the Loan  Documents,  or any judgment  entered by any court in
respect  thereof,  may be brought  in the  courts of the State of Texas,  Travis
County,  or in the United  States courts  located in the State of Texas,  as the
Administrative  Agent shall,  at the direction of the Required  Lenders elect in
their sole discretion,  and Borrower  irrevocably  submits to the  non-exclusive
jurisdiction  of such courts for the purpose of any suit,  action or proceeding.
Borrower  irrevocably  consents to the service of process in any suit, action or
proceeding in said court by the mailing thereof by the  Administrative  Agent by
registered  or certified  mail,  postage  prepaid to  Borrower's  address  shown
opposite its name on the signature pages hereof. Nothing herein or in any of the
other Loan Documents shall affect the right of the Administrative Agent to serve
process in any other  manner  permitted  by law or shall  limit the right of the
Administrative  Agent to bring any action or proceeding against Borrower or with
respect  to any of its  property  in  courts  in other  jurisdictions.  Borrower
irrevocably  waives any objections  which it may now or hereafter have to laying
of venue of any suit,  action or  proceeding  arising out of or relating to this
Agreement or the other Loan Documents brought in the courts located in the State
of Texas,  Dallas County,  and hereby further  irrevocably waives any claim that
any such suit,  action or proceeding  brought in any such court has been brought
in any  inconvenient  forum.  Any action or proceeding  by Borrower  against the
Administrative  Agent or any Lender shall be brought only in a court  located in
Travis County, Texas.

         Section  13.21  Chapter 346.  Borrower  agrees that Chapter 346, of the
Texas Finance Code, as amended (which  regulates  certain  revolving credit loan
documents and revolving tri-party accounts) does not apply to the Obligations.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.

                             SIGNATURE PAGES FOLLOW.


<PAGE>



                                                   Loan Agreement
                                                   Signature Page

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

                                             BORROWER:

                                             PRIME REFRACTIVE MANAGEMENT, L.L.C.

                                                 By: /s/ Teena E. Belcik
                                                 Name: Teena E. Belcik
                                                 Title: Vice President-Treasurer

                                                  Address for Notices:

                                                  1301 Capital of Texas Highway
                                                  Suite C-300
                                                  Austin, Texas 78746
                                                  Attention: Treasurer

                                                   Fax No.: (512) 328-8510
                                                   Telephone No.: (512) 314-4554


<PAGE>


                                            BANK OF AMERICA:

                                            BANK OF AMERICA, N.A.
                                            as Administrative Agent and a Lender

                                            By: /s/ Daneil H. Penkar
                                            Name: Daniel H. Penkar
                                            Title: Senior Vice President

                                            Address for Notices:
                                            515 Congress Avenue, 11th Floor
                                            Post Office Box 908
                                            Austin, Texas 78701-0908

                                            Attention: Wade Morgan

                                            Fax No.: (512) 397-2052
                                            Telephone No.: (512) 397-2241

                                          Lending Office for Base Rate Advances:
                                          515 Congress Avenue, 11th Floor
                                          Post Office Box 908
                                          Austin, TX  78701-0908

                                         Lending Office for Eurodollar Advances:
                                         515 Congress Avenue, 11th Floor
                                         Post Office Box 908
                                         Austin, TX  78701-0908




<PAGE>


                                         BANKBOSTON:

                                         BANKBOSTON, N.A.,

                                         as Documentation Agent, and  a Lender

                                         By: /s/ Walter J. Marullo
                                         Name:    Walter J. Marullo
                                         Title:  Vice President

                                         Address for Notices:

                                         100 Federal Street, MS 01-08-05
                                         P.O. Box 2016
                                         Boston, Massachusetts 02106

                                   Attention: Walter J. Marullo, Vice President

                                   Fax No.: (617) 434-2472

                                   Telephone No.: (617) 434-2308

                                   Lending Office for Base Rate Advances:
                                            100 Federal Street
                                            P. 0. Box 2016
                                            Boston, MA  02106

                                     Lending Office for Eurodollar Advances:
                                                    100 Federal Street
                                                    P.O. Box 2016
                                                    Boston, MA  02106


<PAGE>


                                      BANK ONE, TEXAS, N.A.,
                                      as Lender

                                      By: /s/ Edward W. Lick, Jr.
                                      Name:   Edward W. Lick, Jr.
                                      Title:  Vice President

                                      Address for Notices:
                                      221 West 6th Street, Suite 200
                                      Austin, Texas 78701
                                      Attention: Ed Lick

                                      Fax No.: (512) 479-5720
                                      Telephone No.: (512) 479-5730

                                      Lending Office for Base Rate Advances:
                                         Bank One, Austin
                                         221 West 6th Street, Suite 200
                                         Austin, TX  78701

                                      Lending Office for Eurodollar Advances:
                                         Bank One, Austin
                                         221 West 6th Street, Suite 200
                                         Austin, TX  78701



<PAGE>


                                      FLEET NATIONAL BANK,
                                        as Lender

                                       By: /s/ Walter J. Marullo
                                       Name:    Walter J. Marullo
                                       Title:  Vice President

                                       Address for Notices:
                                       100 Federal Street, MS 01-08-05
                                       P.O. Box 2016
                                       Boston, Massachusetts 02106

                                    Attention: Walter J. Marullo, Vice President
                                    Fax No.: (617) 434-2472
                                    Telephone No.: (617) 434-2308

                                    Lending Office for Base Rate Advances:
                                    Fleet National Bank
                                    One Federal Street
                                    Mail Stop: MA OF D07B
                                    Boston, MA  02110

                                    Lending Office for Eurodollar Advances:
                                    Fleet National Bank
                                    One Federal Street
                                    Mail Stop:  MA OF D07B
                                    Boston, MA  02110


<PAGE>


                                     LASALLE BANK, NATIONAL ASSOCIATION,
                                        as Lender

                                      By: /s/ Dana Friedman
                                      Name: Dana Friedman
                                      Title: Lending Officer

                                      Address for Notices:
                                      135 South LaSalle Street

                                      Chicago, Illinois 60603

                                      Attention: Dana Friedman

                                     Fax No.: (312) 904-6457
                                     Telephone No.: (312) 904-5416

                                     Lending Office for Base Rate Advances:
                                     LaSalle Bank, National Association

                                     135 South LaSalle Street
                                     Chicago, IL  60603

                                     Lending Office for Eurodollar Advances:
                                     LaSalle Bank, National Association
                                     135 South LaSalle Street
                                     Chicago, IL  60603



<PAGE>


GUARANTY FEDERAL BANK, F.S.B.

By: /s/ Chris Harkrider
       Name:  Chris Harkrider
       Title:  Vice President

Addresses for Notices:

301 Congress Avenue
Suite 300
Austin, TX  78701
Attention: Chris Harkrider

Fax No.:     (512) 320-1041
Telephone No.:  (512) 320-1205

Lending Office for Base Rate Advances:

Guaranty Federal Bank, F.S.B.
8333 Douglas Avenue
Dallas, TX 75225

Lending Office for Eurodollar Advances:

Guaranty Federal Bank, F.S.B.
8333 Douglas Avenue
Dallas, TX 75225




                          PRIME MEDICAL SERVICES, INC.

                           FOURTH AMENDED AND RESTATED

                                 LOAN AGREEMENT

                      $86,000,000.00 REVOLVING CREDIT LOAN

                              BANK OF AMERICA, N.A.

                             as Administrative Agent

                                BANKBOSTON, N.A.

                             as Documentation Agent

                                       and

                            THE LENDERS NAMED HEREIN,

                                   as Lenders

                          Dated as of January 31, 2000

                         BANC OF AMERICA SECURITIES LLC

                        as Lead Arranger and Book Manager


<PAGE>



                                 LOAN AGREEMENT

                                       vii


                                TABLE OF CONTENTS


ARTICLE I --  DEFINITIONS......................................................2
         Section 1.1       Amendment and Restatement...........................2
         Section 1.2       Definitions.........................................2
         Section 1.3       Other Definitional Provisions......................22

ARTICLE II --  ADVANCES.......................................................23
         Section 2.1       Commitments........................................23
         Section 2.2        Notes.............................................23
         Section 2.3       Repayment of Advances..............................23
         Section 2.4       Interest...........................................23
         Section 2.5       Borrowing Procedure................................24
         Section 2.6       Continuations; Conversions.........................24
         Section 2.7       Use of Proceeds....................................25
         Section 2.8       Fees...............................................25

ARTICLE III --  PAYMENTS......................................................25
         Section 3.1       Method of Payment..................................25
         Section 3.2       Optional Prepayment................................25
         Section 3.3       Mandatory Prepayments..............................26
         Section 3.4       Pro Rata Treatment.................................26
         Section 3.5       Non-Receipt of Funds by the Administrative Agent...26
         Section 3.6       Withholding Taxes..................................26
         Section 3.7       Withholding Tax Exemption..........................27
         Section 3.8       Computation of Interest............................27
         Section 3.9       Order of Application...............................27

ARTICLE IV --  YIELD PROTECTION AND ILLEGALITY................................28
         Section 4.1       Additional Costs...................................28
         Section 4.2       Limitation on Eurodollar Advances..................29
         Section 4.3       Illegality.........................................29
         Section 4.4       Treatment of Eurodollar Advances...................30
         Section 4.5       Compensation.......................................30
         Section 4.6       Capital Adequacy...................................31

ARTICLE V --  SECURITY........................................................31
         Section 5.1       Collateral.........................................31
         Section 5.2       Future Liens. .....................................32
         Section 5.3       Release of Collateral..............................33
         Section 5.4       Setoff.............................................33

ARTICLE VI --  CONDITIONS PRECEDENT...........................................33
                  Section 6.1       Initial Advance...........................33
         Section 6.2       All Advances.......................................35

ARTICLE VII --  REPRESENTATIONS AND WARRANTIES................................36
         Section 7.1       Existence..........................................36
         Section 7.2       Financial Statements...............................36
         Section 7.3       Corporate Action:  No Breach.......................37
         Section 7.4       Operation of Business..............................37
         Section 7.5       Litigation and Judgments...........................37
         Section 7.6       Rights in Properties; Liens........................37
         Section 7.7       Enforceability.....................................37
         Section 7.8       Approvals..........................................37
         Section 7.9       Debt...............................................38
         Section 7.10      Taxes..............................................38
         Section 7.11      Use of Proceeds; Margin Securities.................38
         Section 7.12      ERISA..............................................38
         Section 7.13      Disclosure.........................................38
         Section 7.14      Subsidiaries; Partnerships.........................38
         Section 7.15      Agreements.........................................39
         Section 7.16      Compliance with Legal Requirements;
                                 Governmental Authorizations..................39
         Section 7.17      Investment Company Act.............................40
         Section 7.18      Public Utility Holding Company Act.................40
         Section 7.19      Environmental Matters..............................40
         Section 7.20      Year 2000 Compliance...............................40

ARTICLE VIII --  POSITIVE COVENANTS...........................................40
         Section 8.1       Reporting Requirements.............................40
         Section 8.2       Maintenance of Existence; Conduct of Business......43
         Section 8.3       Maintenance of Properties..........................43
         Section 8.4       Taxes and Claims...................................43
         Section 8.5       Insurance..........................................43
         Section 8.6       Inspection Rights..................................44
         Section 8.7       Keeping Books and Records..........................44
         Section 8.8       Compliance with Laws...............................44
         Section 8.9       Compliance with Agreements.........................44
         Section 8.10      Further Assurances.................................44
         Section 8.11      ERISA..............................................44
         Section 8.12      Information Relating to Proposed Acquisitions......44
         Section 8.13      After-Acquired Subsidiaries........................44
         Section 8.14      Syndication Cooperation............................45

ARTICLE IX --  NEGATIVE COVENANTS.............................................45
         Section 9.1A      Debt...............................................45
         Section 9.1B      Debt of Refractive Entities........................46
         Section 9.2       Limitation on Liens................................46
         Section 9.3       Mergers, Etc.......................................46
         Section 9.4       Restricted Payments................................47
         Section 9.5       Investments........................................47
         Section 9.6       Limitation on Issuance of Capital Stock............49
         Section 9.7       Transactions With Affiliates.......................49
         Section 9.8       Disposition of Assets.  ...........................49
         Section 9.9       Sale and Leaseback.................................50
         Section 9.10      Prepayment of Debt.................................50
         Section 9.11      Nature of Business.................................50
         Section 9.12      Environmental Protection...........................50
         Section 9.13      Accounting.........................................50
         Section 9.14      Amendment of Partnership
                                and Management Agreements.....................50
         Section 9.15      Financial Hedges...................................50
         Section 9.16      Control of Prime Refractive, L.L.C.................51

ARTICLE X --  FINANCIAL COVENANTS.............................................51
         Section 10.1      Total Net Funded Debt to EBITDA....................51
         Section 10.2      Senior Net Funded Debt To EBITDA Ratio.............51
         Section 10.3      Debt Service Coverage Ratio........................51
         Section 10.4      Consolidated Net Worth.............................52

ARTICLE XI --  DEFAULT........................................................52
         Section 11.1      Events of Default..................................52
         Section 11.2      Remedies...........................................54
         Section 11.3      Performance by the Administrative Agent............54

ARTICLE XII --  THE ADMINISTRATIVE AGENT......................................55
         Section 12.1      Appointment, Powers and Immunities.................55
         Section 12.2      Rights of Administrative Agent as a Lender.........56
         Section 12.3      Sharing of Payments, Etc...........................56
         Section 12.4      Indemnification....................................57
         Section 12.5      Independent Credit Decisions.......................57
         Section 12.6      Several Commitments................................58
         Section 12.7      Successor Administrative Agent.....................58
         Section 12.8      Independent Contractor.............................58

ARTICLE XIII --  MISCELLANEOUS................................................59
         Section 13.1      Expenses...........................................59
         Section 13.2      Indemnification....................................59
         Section 13.3      No Duty............................................59
         Section 13.4      No Fiduciary Relationship..........................60
         Section 13.5      No Waiver; Cumulative Remedies.....................60
         Section 13.6      Successors and Assigns.............................60
         Section 13.7      Survival...........................................62
         Section 13.8      ENTIRE AGREEMENT...................................62
         Section 13.9      Amendments, Etc....................................63
         Section 13.10     Maximum Interest Rate..............................63
         Section 13.11     Notices............................................63
         Section 13.12     Governing Law......................................64
         Section 13.13     Counterparts.......................................64
         Section 13.14     Severability.......................................64
         Section 13.15     Headings...........................................64
         Section 13.16     Construction.......................................64
         Section 13.17     Independence of Covenants..........................64
         Section 13.18     Confidentiality....................................64
         Section 13.19     Restatement of Original Credit Agreement...........65
         Section 13.20     Assignments and Assumptions Among Lenders.  .......65
         Section 13.21     Waiver of Jury Trial...............................65
         Section 13.22     Choice of Forum; Consent to Service
                                of Process and Jurisdiction. .................65
         Section 13.23     Chapter 346........................................66



<PAGE>






                                INDEX TO EXHIBITS

Exhibit           Description of Exhibit

A                 Advance Request Form
B                 Form of Assignment and Acceptance
C                 Form of Note
D                 Perfection Certificate

E                 Form of Opinion of Counsel for Borrower and the Guarantors
F                 Compliance Certificate
G                 Permitted Acquisition Certificate
H                 Permitted Passive Investment Certificate
I                 Permitted Other Business Acquisition Certificate
J                 Permitted Refractive Acquisition Certificate
K                 Non-Borrower and Guarantor Acquisition Certificate
L                 Form of Subordinated Note
M                 Form of Subordination Agreement

                               INDEX TO SCHEDULES

Schedule Description of Schedule

1                 Commitments
2                 Guarantors
3                 Partnerships
7.5               Existing Litigation
7.9               Existing Debt
7.14.1            Capitalization of Subsidiaries
7.14.2            Partners
7.15              Agreements
7.16              Governmental Disclosures
7.19              Environmental Matters
9.2               Existing Liens




<PAGE>



                                                                  LOAN AGREEMENT


                   FOURTH AMENDED AND RESTATED LOAN AGREEMENT

         THIS FOURTH  AMENDED AND RESTATED  LOAN  AGREEMENT  (the  "Agreement"),
dated as of January 31, 2000, is among PRIME MEDICAL SERVICES,  INC., a Delaware
corporation  ("Borrower"),  each of the  lenders or other  lending  institutions
which is or which  may  from  time to time  become  a  signatory  hereto  or any
successor or assignee thereof (collectively,  the "Lenders" and individually,  a
"Lender"),  BANK OF  AMERICA,  N.A.  ("Bank of  America"),  a  national  banking
association,  as Administrative  Agent for itself and the other Lenders (in such
capacity,  together with its  successors in such capacity,  the  "Administrative
Agent"), and BANKBOSTON, N.A. ("BankBoston"), a national banking association, as
Documentation Agent for itself and the other Lenders (in such capacity, together
with its successors in such capacity, the "Documentation Agent").

                                 R E C I T A L S

                  1.  Reference is hereby made to that  certain  Loan  Agreement
         dated as of  November  28,  1994,  by and between  Borrower,  the Banks
         defined therein,  and BankBoston (then known as The First National Bank
         of Boston),  as Agent for the Banks defined therein, as amended by that
         certain First  Amendment to Loan Agreement dated as of August 17, 1995,
         as amended by the Amended and Restated Loan Agreement dated as of April
         26, 1996 among Borrower,  BankBoston,  as Administrative Agent, Bank of
         America (then known as NationsBank of Texas,  N.A.),  as  Documentation
         Agent,  and BankBoston,  as Syndication  Agent, as amended by the First
         Amendment to Amended and Restated Loan  Agreement  dated as of June 14,
         1996 among  Borrower,  BankBoston,  as  Administrative  Agent,  Bank of
         America (then known as NationsBank of Texas,  N.A.),  as  Documentation
         Agent,  and the other banks named  therein,  as further  amended by the
         Second Amended and Restated Loan  Agreement  dated as of March 31, 1997
         among Borrower,  BankBoston,  as Administrative  Agent, Bank of America
         (then known as NationsBank of Texas, N.A.), as Documentation Agent, and
         NationsBanc  Capital Markets,  Inc., and the lenders named therein,  as
         amended and waived from time to time,  as further  amended by the Third
         Amended and Restated  Loan  Agreement  dated as of April 20, 1998 among
         Borrower, BankBoston, as original Administrative Agent and as successor
         Documentation  Agent,  Bank of America  (then known as  NationsBank  of
         Texas,  N.A.),  as  original   Documentation  Agent  and  as  successor
         Administrative  Agent,  and the lenders named  therein,  as amended and
         waived  from  time  to  time   (collectively,   the  "Original   Credit
         Agreement").

                  2.  Subject  to the terms  and  conditions  set  forth  below,
         Borrower and  "Required  Lenders"  (as defined in the  Original  Credit
         Agreement) desire to entirely amend,  modify,  and restate the Original
         Credit Agreement,  to provide for, among other things (a) a decrease in
         the maximum amount available under the Revolving  Credit  Commitment to
         $86,000,000,  and (b) modification and amendment to certain  provisions
         therein,  subject  to the  terms  and  conditions  set  forth  in  this
         Agreement.

                  3.  The  amendment  and  restatement  of the  Original  Credit
         Agreement hereunder is not intended by the parties to constitute either
         a novation or a  discharge  or  satisfaction  of the  indebtedness  and
         "Obligations"  under the Original Credit Agreement,  which indebtedness
         and  obligations  under the  Original  Credit  Agreement  shall  remain
         outstanding hereunder on the terms and conditions hereinafter provided.


<PAGE>


         In consideration  of the foregoing and the mutual  covenants  contained
herein, Borrower, Bank of America (in its capacity as Administrative Agent under
the Original  Credit  Agreement),  BankBoston (in its capacity as  Documentation
Agent under the  Original  Credit  Agreement)  and  Required  Lenders  under the
Original  Credit  Agreement  agree that,  effective  upon the Closing Date,  the
Original Credit Agreement is amended and restated in its entirety, as follows:

                            ARTICLE I -- DEFINITIONS

                  Section 1.1 Amendment and  Restatement.  This  Agreement is in
         renewal,  extension,  modification,  and  restatement  of the  Original
         Credit  Agreement and constitutes and is hereby  designated by Borrower
         as  "Designated  Senior  Debt" as defined  in the  Senior  Subordinated
         Indenture.

               Section 1.2 Definitions. As used in this Agreement, the following
          terms shall have the following meanings:

         "Acquisition"   means  any  transaction,   or  any  series  of  related
transactions,  consummated on or after the date hereof,  by which Borrower,  any
Guarantor,  or any other  Subsidiary  of  Borrower  directly or  indirectly  (a)
acquires all or substantially  all of the assets of any Person,  whether through
purchase of assets, merger, or otherwise, (b) acquires (in one transaction or as
the most recent transaction in a series of transactions) at least a majority (in
number of votes) of the  securities  (or  similar  ownership  interests)  of any
Person, or (c) acquires (in one transaction or as the most recent transaction in
a series of  transactions)  at least a majority  of the general  partnership  or
managing member interests of any Person, or (d) acquires additional  Partnership
or other equity interests in any Subsidiary.

         "Additional Costs" has the meaning specified in Section 4.1.

         "Adjusted EBITDA" means for any Person for any period,  the sum of: (i)
EBITDA,  except  in  the  case  of  any  Target  Company  in  respect  of  which
Consolidated  Earn-Out  Indebtedness  is payable,  EBITDA of such Target Company
shall be  increased  by the amount,  if any, by which such  Person's  annualized
fiscal year to date  EBITDA used in the  calculation  of  Consolidated  Earn-Out
Indebtedness, exceeds the actual EBITDA for the four previous fiscal quarters of
such  Person  for  such  period,  plus  (ii)  without   duplication,   all  cash
Distributions  related to minority interests in Partnership actually received by
Prime Refractive  Management,  L.L.C., plus (iii) without duplication,  on a pro
forma basis,  the EBITDA of any Target Company acquired during such period as if
it were acquired on the first day of such period.

         "Adjusted  Eurodollar Rate" means,  for any Eurodollar  Advance for any
Interest Period therefor, the rate per annum (rounded upwards, if necessary,  to
the nearest 0.01%) determined by the Administrative Agent to be equal to (a) the
Eurodollar Rate for such Eurodollar  Advance for such Interest Period divided by
(b) 1.00 minus the  Reserve  Requirement  for such  Eurodollar  Advance for such
Interest Period.

     "Administrative  Agent"  means Bank of  America,  N.A.,  and its  permitted
successors  and  assigns  as  "Administrative  Agent"  for  Lenders  under  this
Agreement.

         "Advance"  means each advance of funds by the Lenders or any of them to
Borrower pursuant to Section 2.5(a).


<PAGE>


         "Advance Request Form" means a certificate,  in substantially  the form
of Exhibit A, properly completed and signed by Borrower requesting an Advance.

         "Advancing  Term Loan Facility"  means the  $14,000,000  Advancing Term
Loan pursuant to the Loan Agreement dated the date hereof among Bank of America,
N.A., as Administrative  Agent,  BankBoston,  N.A., as Documentation  Agent, the
lenders  from  time to time  party  thereto,  and Prime  Refractive  Management,
L.L.C., as borrower.

         "Affiliate" means, as to any Person, any other Person (a) that directly
or indirectly, through one or more intermediaries, Controls or is Controlled by,
or is under common  Control with,  such Person,  (b) that directly or indirectly
beneficially  owns or holds  five  percent  (5%) or more of any  class of voting
stock of such  Person,  or (c) five  percent (5%) or more of the voting stock of
which is  directly  or  indirectly  beneficially  owned or held by the Person in
question;  provided,  however,  in no event  shall the  Agents or any  Lender be
deemed an Affiliate of Borrower or any of its Subsidiaries.

         "After-Acquired Subsidiary" has the meaning specified in Section 8.13.

     "Agents" means the Administrative  Agent, the Documentation  Agent, and the
Lead Arranger. "Agent" means any one of the Agents.

         "Alternate  Base  Rate"  means,  at any time,  the  greater  of (a) the
variable rate of interest  established  from time to time by the  Administrative
Agent as its  "base  rate"  and set by the  Administrative  Agent  as a  general
reference  rate of interest  charged by the  Administrative  Agent,  and (b) the
Federal Funds Rate plus  one-half of one percent  (.5%).  Borrower  acknowledges
that the  Administrative  Agent may,  from time to time,  extend credit to other
borrowers at rates of interest varying from, and having no relationship to, such
general  reference  rate.  Each change in the  Alternate  Base Rate shall become
effective  without prior notice to Borrower  automatically  as of the opening of
business on the date of such change in the Alternate Base Rate.

         "Alternate  Base Rate  Advances"  means  Advances that bear interest at
rates based upon the Alternate Base Rate.

         "Applicable  Lending  Office"  means for each  Lender  and each Type of
Advance,  the lending  office of such Lender (or of an Affiliate of such Lender)
designated for such Type of Advance below its name on the signature pages hereof
or an Assignment and  Acceptance,  or such other office of such Lender (or of an
Affiliate  of such  Lender)  as such  Lender  may from time to time  specify  to
Borrower  and the  Administrative  Agent as the office by which its  Advances of
such Type are to be made and maintained.

         "Applicable  Margin" means the interest  margin over the Alternate Base
Rate or the Adjusted Eurodollar Rate, as the case may be, for Advances under the
Commitment  (a) from the date hereof until the delivery of financial  statements
and a  compliance  certificate  for the period  ending  December  31,  1999,  as
required  hereunder,  one-half of one percent  (.500%) for  Alternate  Base Rate
Advances,  and two percent (2.000%) for Eurodollar Advances; and (b) thereafter,
based on the Net Total Funded Debt to EBITDA Ratio as of and for the most recent
four (4)  quarter  period  ending on or before  the date of  determination,  the
margin set forth opposite such ratio below:


<PAGE>


========================== =========================== =========================

   Applicable Margin

    Net Total Funded              Alternate Base Rate       Applicable Margin
   Debt to EBITDA Ratio               Advances             Eurodollar Advances

- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

Less than 1.5 to 1.0                   .375%                      1.375%
- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

- -------------------------- --------------------------- -------------------------
- -------------------------- --------------------------- -------------------------

Greater than or
  equal to 2.75 to 1.0                .875%                      2.375%
========================== =========================== =========================

The Net Total Funded Debt to EBITDA Ratio shall be determined from the then most
current of either (a) the quarterly or annual  financial  statements and related
compliance certificate delivered pursuant to Section 8.1, or (b) the most recent
Advance Request Form for a Permitted Acquisition,  Permitted Passive Investment,
Permitted  Other  Business  Acquisition,  or Permitted  Refractive  Acquisition,
calculating  any  adjustments  to such  ratio  necessitated  as a result  of the
Permitted  Acquisition,  Permitted Passive Investment,  Permitted Other Business
Acquisition,  or Permitted  Refractive  Acquisition,  for which such Advance was
made.  The  adjustment,  if any, to the  Applicable  Margin  shall be  effective
commencing  on the fifth (5th)  Business  Day after  delivery of such  financial
statements  (and  related  compliance  certificate)  or the  respective  date of
Advance for a Permitted  Acquisition,  Permitted Passive  Investment,  Permitted
Other Business Acquisition, or Permitted Refractive Acquisition, as the case may
be. If Borrower fails at any time to furnish to the Administrative Agent and the
Lenders the financial statements and related compliance  certificate as required
to be delivered  pursuant to Section  8.1,  then the maximum  Applicable  Margin
shall  apply  until  such  time  as such  financial  statements  and  compliance
certificates are so delivered.

         "Applicable  Rate"  means:  (a) during any period that an Advance is an
Alternate Base Rate Advance, the Alternate Base Rate plus the Applicable Margin;
and (b) during any period that an Advance is a Eurodollar Advance,  the Adjusted
Eurodollar Rate plus the Applicable Margin.

         "Applicable  Unused  Fee  Percentage"  means  the per  annum  rate with
respect to the unused portion of the  Commitments as follows:  (a) from the date
hereof until delivery of financial  statements and a compliance  certificate for
the period  ending  December  31,1999,  as required  hereunder,  one-half of one
percent  (.500%);  and (b)  thereafter,  based on the Net Total  Funded  Debt to
EBITDA Ratio as of and for the most recent four (4) quarter  period ending on or
before the date of  determination,  the percentage set forth opposite such ratio
below:

====================================================== =========================

                  Net Total Funded                      Applicable Unused Fee
                 Debt to EBITDA Ratio                         Percentage

- ------------------------------------------------------ -------------------------
- ------------------------------------------------------ -------------------------

               Less than 1.5 to 1.0                              .300%
- ------------------------------------------------------ -------------------------
- ------------------------------------------------------ -------------------------

    Less than 2.0 to 1.0 but greater than or equal to            .375%
           1.5 to 1.0

    Greater than or equal to 2.0 to 1.0                          .500%
====================================================== =========================



<PAGE>


The Applicable  Unused Fee Percentage  shall be adjusted,  if necessary,  at the
same time as adjustments to the Applicable Margin. If Borrower fails at any time
to furnish to the Administrative  Agent and the Lenders the financial statements
and related  compliance  certificate  as required  to be  delivered  pursuant to
Section 8.1, then the maximum Applicable Unused Fee Percentage shall apply until
such  time as such  financial  statements  and  compliance  certificates  are so
delivered.

         "Assignee" has the meaning specified in Section 13.6.

         "Assigning Lender" has the meaning specified in Section 13.6.

         "Assignment and Acceptance" means an assignment and acceptance  entered
into by an Assigning Lender and its Assignee and accepted by the  Administrative
Agent pursuant to Section 13.6, in substantially the form of Exhibit B.

     "Bank of America" means Bank of America,  N.A. and its permitted successors
and assigns.

     "BankBoston"  means  BankBoston,  N.A.  and its  permitted  successors  and
assigns.

         "Basle  Accord" means the proposals for  risk-based  capital  framework
described  by  the  Basle  Committee  on  Banking  Regulations  and  Supervisory
Practices  in  its  paper   entitled   "International   Convergence  of  Capital
Measurement and Capital  Standards" dated July,  1988, as amended,  supplemented
and  otherwise  modified  and in effect  from time to time,  or any  replacement
thereof.

         "BDEC  Acquisition"  means the  acquisition by PMOI of an undivided 60%
interest  in the  "refractive  surgery"  assets of Barnet  Dulaney  Eye  Center,
P.L.L.C., and the contribution by PMOI of such assets to Prime/BDEC Acquisition,
L.L.C.

         "Borrower Security Agreement" means (a) the Borrower Security Agreement
dated as of April 26,  1996,  executed by Borrower  in favor of  BankBoston,  as
predecessor  Administrative Agent to Administrative Agent for the benefit of the
Lenders,  as the same may be amended,  supplemented,  or  modified  from time to
time,  including  (b) the Consent,  Confirmation  and  Ratification  of Borrower
Security  Agreement  dated  as of  March  31,  1997,  (c)  the  Second  Consent,
Confirmation and Ratification of Borrower  Security  Agreement dated as of April
20, 1998, and (d) the Third Consent,  Confirmation  and Ratification of Borrower
Security  Agreement  dated  as of  the  date  hereof,  which  Borrower  Security
Agreement is in renewal, amendment, restatement and substitution of that certain
Borrower  Security  Agreement  dated November 28, 1994,  executed by Borrower in
favor of  BankBoston,  as  predecessor  Administrative  Agent to  Administrative
Agent,  for the benefit of the Lenders under the Original Credit  Agreement,  as
amended pursuant to that First Amendment to Borrower Security Agreement dated as
of August 17, 1995, and any other security  agreement executed from time to time
by Borrower  and  delivered to the  Administrative  Agent for the benefit of the
Lenders, all as amended, renewed, restated, and substituted from time to time.

         "Business Day" means (a) any day on which the  Administrative  Agent is
open for regular  business,  and (b) with respect to all  borrowings,  payments,
Conversions,  Continuations,  Interest  Periods,  and notices in connection with
Eurodollar  Advances,  any day which is a Business  Day  described in clause (a)
above and which is also a day on which  dealings in Dollar  deposits are carried
out in the London interbank market.


<PAGE>


         "Capital Lease Obligations" means, as to any Person, the obligations of
such Person to pay rent or other  amounts  under a lease of (or other  agreement
conveying the right to use) real and/or personal property, which obligations are
required to be  classified  and  accounted  for as a capital  lease on a balance
sheet of such Person under GAAP. For purposes of this  Agreement,  the amount of
such Capital Lease  Obligations  shall be the  capitalized  amount  thereof,  as
determined in accordance with GAAP.

         "Cash  Equivalent"  means any  investments  of the Companies  which are
permitted by Section  9.5(a),  and which  mature  within 180 days of any date of
determination,  and which are  unconditionally  available  for  repayment of the
Obligations, upon liquidation.

         "Change in Control"  means a Change of Control as defined in the Senior
Subordinated Indenture.

         "Code" means the Internal  Revenue  Code of 1986,  as amended,  and the
regulations promulgated and rulings issued thereunder.

         "Collateral" has the meaning specified in Section 5.1.

         "Collateral  Documents"  means the  Borrower  Security  Agreement,  the
Guarantor Security Agreements,  the Pledge Agreements, and all other collateral,
security,  lien  creating  agreements  executed or  delivered  pursuant to or in
connection with this Agreement, as the same may be amended,  modified,  renewed,
or supplemented from time to time.

         "Commitment" means, as to each Lender as of any date, the obligation of
such Lender on such date to make  Advances  hereunder in an aggregate  principal
amount at any time  outstanding  up to but not  exceeding  the  amount  shown on
Schedule 1 as its  Commitment,  as the same may be reduced  pursuant  to Section
2.1(b) or terminated  pursuant to Section 2.1(b) or Section 11.2 and as the same
may be increased or decreased from time to time by further  assignment  pursuant
to Section 13.6.  "Commitments"  means the  Commitments of all of the Lenders in
the original aggregate amount of $86,000,000.00.

         "Companies" means Borrower and its Subsidiaries.

         "Confidential  Information"  means any and all information  relating to
the Companies,  including,  without limitation,  information relating to each of
the Company's financial condition, business plans, management, earnings, assets,
liabilities,   contracts,   processes,   products,   research  and   development
activities, intellectual property, services, customers, suppliers, marketing and
sales.  In addition,  Confidential  Information  shall include any and all other
information  marked  or  identified  in  writing  by  any of  the  Companies  as
"Confidential"  or  "Confidential  Information"  and  provided  by  each  of the
Companies or its representatives to any of the Lenders or the Agents or obtained
by the  Lenders or the  Agents  after an  inspection  pursuant  to Section  8.6.
Notwithstanding the foregoing, "Confidential Information" shall not include:

                  (i) any  information  known to an  Agent or a Lender  prior to
         disclosure  by  any  of  the  Companies  or  its  representatives,   as
         documented prior to such disclosure in such Agent's or Lender's written
         records;


<PAGE>


                  (ii) any information  which an Agent or a Lender  demonstrates
         became available to it on a non-confidential basis from a source (other
         than  any of the  Companies)  who is  not  bound  by a  confidentiality
         agreement with, or any other contractual, legal or fiduciary obligation
         of  confidentiality  to, any of the  Companies  or any other party with
         respect to such information;

                  (iii) any information which an Agent or a Lender  demonstrates
         is or becomes generally  available to the public other than as a result
         of a disclosure by it in breach of Section 13.18; and

                  (iv) any information  which an Agent or a Lender  demonstrates
         was  conceived of or developed  by it or any of its  employees  without
         access  or  reference,  directly  or  indirectly,  to the  Confidential
         Information.

         "Consolidated  Earn-Out  Indebtedness"  means as to any Person,  at any
time, in connection with each  applicable  Permitted  Refractive  Acquisition in
which an earn-out payment or other post-closing payment or payments is or may be
due pursuant to the applicable purchase or acquisition agreement,  the projected
aggregate  amount of such  earn-out or  post-closing  payments  that would be or
become due based upon all events or  circumstances  that have occurred as of any
date of determination, regardless of whether any such payments are then actually
payable under the terms of the  applicable  purchase or  acquisition  agreement;
provided that to the extent any such payments are based on net income, revenues,
EBITDA or similar  financial  performance  criteria of any Target  Company for a
defined   post-closing  period  or  periods,  the  actual  applicable  financial
performance  during the  applicable  period to date shall be  utilized in making
such projection.  Borrower shall submit the calculation of Consolidated Earn-Out
Indebtedness with respect to each applicable Permitted  Refractive  Acquisition,
together with each compliance  certificate delivered pursuant to Section 8.1(d),
together  with any  applicable  supporting  documentation,  all of which must be
satisfactory to Administrative Agent.

         "Consolidated  Net Income"  means,  for any Person for any period,  the
amount which, in conformity with GAAP,  would be shown on a consolidated  income
statement of such Person as net income for such period,  after  deduction of any
minority interests.

         "Consolidated  Net Worth" means,  at any  particular  time, all amounts
which, in conformity with GAAP, would be included as  stockholders'  equity on a
consolidated balance sheet of the Companies.

         "Continue,"  "Continuation," and "Continued" refers to the continuation
pursuant to Section 2.6 of a Eurodollar  Advance from one Interest Period to the
next Interest Period.

         "Control" means the possession, directly or indirectly, of the power to
direct or cause the direction of the management or policies of a Person, whether
through the ownership of voting  securities  or other  ownership  interests,  by
contract or otherwise.  "Controlling" and "Controlled" have meanings correlative
thereto.

         "Conversion" and "Converted" refers to a conversion pursuant to Section
2.6 of one Type of Advance into another Type of Advance.


<PAGE>


         "Debt"  means as to any  Person at any time  (without  duplication  and
without duplication among the Companies): (a) all obligations of such Person for
borrowed money;  (b) all obligations of such Person  evidenced by bonds,  notes,
debentures,  or other similar instruments,  including,  without limitation,  the
Senior  Subordinated  Notes;  (c)  all  obligations  of such  Person  to pay the
deferred purchase price of property or services,  including, without limitation,
Consolidated Earn-Out Indebtedness, except trade accounts payable of such Person
arising in the  ordinary  course of business  that are not past due by more than
ninety (90) days;  (d) all Capital  Lease  Obligations  of such Person;  (e) all
indebtedness  or other  obligations  of others of the  types  described  in this
definition, if Guaranteed by such Person or for which such Person is liable as a
partner in any  partnership  or joint  venturer  in any joint  venture;  (f) all
obligations secured by a Lien existing on property owned by such Person, whether
or not the  obligations  secured thereby have been assumed by such Person or are
non-recourse to the credit of such Person; (g) all reimbursement  obligations of
such Person  (whether  contingent or otherwise) in respect of letters of credit,
banker's  acceptances,  surety or other bonds and similar  instruments;  (h) all
obligations under any Financial Hedge, and (i) all liabilities of such Person in
respect of unfunded vested benefits under any Plan; provided,  however, that the
term  Debt  shall  not  include  endorsements  of  instruments  for  deposit  or
collection in the ordinary course of business.

         "Debt Service Coverage Ratio" means, as to the Companies  (including on
a pro forma basis any Company acquired in any Permitted  Acquisition,  Permitted
Other Business Acquisition,  or Permitted Refractive Acquisition for each of the
components of and for the entire period of calculation of Debt Service  Coverage
Ratio) for any period, the ratio of (a) the sum of: (i) Adjusted EBITDA for such
period, minus (ii) the aggregate amount of capital expenditures made during such
period,  minus (iii) all cash tax  payments,  divided by (b) the sum of: (w) all
cash interest  payments payable during such period in respect of all Debt of the
Companies  (without deduction for any minority  interests),  plus (x) 1/7 of the
outstanding   principal   amount  of  the  Loans  and  1/7  of  the  outstanding
"Obligations"  under  the  Advancing  Term  Loan  Facility  as of  any  date  of
determination,  plus (y) 1/7 of the Consolidated Earn-Out Indebtedness as of any
date of determination,  plus (z) any regularly  scheduled  principal payments on
Debt (including Subordinated Debt, but excluding Earn-Out Indebtedness),  all as
determined  on a rolling four (4) quarter and  consolidated  basis in accordance
with GAAP.

         "Default"  means an Event of Default or the  occurrence  of an event or
condition  which  with the  giving of notice or the lapse of time or both  would
become an Event of Default.

         "Default  Rate" means the lesser of (a) the Maximum  Rate,  and (b) the
sum of the  Alternate  Base Rate in effect  from day to day plus the  Applicable
Margin plus two percent (2%).

         "Defaulting  Lender"  means any Lender that in  Administrative  Agent's
reasonable  judgment  has  defaulted  on  any  of  its  obligations  under  this
Agreement.

         "Documentation  Agent"  means  BankBoston,   N.A.,  and  its  permitted
successors  and  assigns  as  "Documentation   Agent"  for  Lenders  under  this
Agreement.

         "Dollars" and "$" mean lawful money of the United States of America.

         "EBITDA" means,  for any Person for any period:  (a)  Consolidated  Net
Income  of such  Person  for such  period,  determined  after  deduction  of any
minority interests,  plus (b) all amounts deducted therefrom during such period,
in conformity with GAAP, for interest,  taxes,  depreciation  and  amortization,
provided  that  cash flow  from  Permitted  Passive  Investments  shall  only be
included in the  calculation  of EBITDA to the extent:  (i) it has been actually
received by Borrower or a Guarantor, and (ii) it does not exceed fifteen percent
(15%) of total EBITDA for such period.


<PAGE>


         "Eligible  Assignee" means (i) a Lender; (ii) an Affiliate of a Lender;
or (iii) any other Person approved by the  Administrative  Agent (which approval
shall not be  unreasonably  withheld  or delayed by  Administrative  Agent) and,
unless  an Event of  Default  has  occurred  and is  continuing  at the time any
assignment is effected in accordance with Section 13.6, Borrower,  such approval
not to be  unreasonably  withheld or delayed by Borrower and such approval to be
deemed given by Borrower if no objection is received by the assigning Lender and
the Administrative Agent from Borrower within two (2) Business Days after notice
of such  proposed  assignment  has been  provided  by the  assigning  Lender  to
Borrower;  provided, however, that neither Borrower nor an Affiliate of Borrower
shall qualify as an Eligible Assignee.

     "Environmental  Laws"  means any and all  federal,  state,  and local laws,
regulations,  and requirements pertaining to health, safety, or the environment,
including,   without  limitation,  the  Comprehensive   Environmental  Response,
Compensation and Liability Act of 1980, 42 U.S.C.ss.  9601 et seq., the Resource
Conservation  and  Recovery  Act  of  1976,  42  U.S.C.ss.  6901  et  seq.,  the
Occupational  Safety and Health Act, 29 U.S.C.ss.651 et seq., the Clean Air Act,
42 U.S.C.ss.  7401 et seq., the Clean Water Act, 33 U.S.C.ss.  1251 et seq., and
the Toxic  Substances  Control  Act,  15  U.S.C.ss.2601  et seq.,  as such laws,
regulations, and requirements may be amended or supplemented from time to time.

         "Environmental  Liabilities"  means, as to any Person, all liabilities,
obligations,  responsibilities,  Remedial  Actions,  losses,  damages,  punitive
damages,  consequential damages, treble damages, costs, and expenses (including,
without limitation,  all reasonable fees, disbursements and expenses of counsel,
expert and consulting fees and costs of investigation and feasibility  studies),
fines, penalties,  sanctions,  and interest incurred as a result of any claim or
demand,  by any Person,  whether  based in  contract,  tort,  implied or express
warranty,   strict   liability,   criminal  or  civil  statute,   including  any
Environmental Law, permit, order or agreement with any Governmental Authority or
other Person,  arising from  environmental,  health or safety  conditions or the
Release or  threatened  Release of a Hazardous  Material  into the  environment,
resulting  from the past,  present,  or future  operations of such Person or its
Affiliates.

         "ERISA" means the Employee  Retirement  Income Security Act of 1974, as
amended from time to time,  and the  regulations  and published  interpretations
thereunder.

         "ERISA Affiliate" means any corporation or trade or business which is a
member of the same  controlled  group of  corporations  (within  the  meaning of
Section 414(b) of the Code) as Borrower or is under common  control  (within the
meaning of Section 414(c) of the Code) with Borrower.

         "Eurodollar  Advances"  means  Advances the interest rates on which are
determined on the basis of the rates  referred to in the definition of "Adjusted
Eurodollar Rate" in this Section 1.1.

         "Eurodollar  Rate" means,  for any Eurodollar  Advance for any Interest
Period  therefor,  the rate per annum  (rounded  upwards,  if necessary,  to the
nearest 1/100 of 1%) appearing on Telerate Page 3750 (or any successor  page) as
the London interbank offered rate for deposits in Dollars at approximately 11:00
a.m.  (London  time) two Business  Days prior to the first day of such  Interest
Period for a term  comparable  to such Interest  Period.  If for any reason such
rate is not available, the term "Eurodollar Rate" shall mean, for any Eurodollar
Advance for any Interest Period therefor,  the rate per annum (rounded  upwards,
if necessary,  to the nearest 1/100 of 1%) appearing on Reuters Screen LIBO Page
as the London  interbank  offered rate for deposits in Dollars at  approximately
11:00  a.m.  (London  time)  two  Business  Days  prior to the first day of such
Interest  Period  for a term  comparable  to  such  Interest  Period,  provided,
however,  if more than one rate is  specified on Reuters  Screen LIBO Page,  the
applicable rate shall be the arithmetic mean of all such rates.

         "Event of Default" has the meaning specified in Section 11.1.

     "Excepted   Subsidiaries"   means   FastStart,   Inc.,  a  North   Carolina
corporation,   National  Lithotripters   Association,   Inc.  a  North  Carolina
corporation, and MedTech Investments, Inc., a North Carolina corporation.

<PAGE>


         "Exchange  Notes" means those certain senior  subordinated  notes to be
issued  in  exchange  for  the  originally  issued  Senior  Subordinated  Notes,
containing  substantially  the same terms as the  original  Senior  Subordinated
Notes.

         "Existing Permitted Passive Investments" means ownership by Borrower or
any Subsidiary of a 32.5% interest in Southern California Stone Center,  L.L.C.,
a California  limited  liability  company and a 38.25% interest in TENN-GA Stone
Group Two, a Tennessee general partnership.

         "Federal  Funds Rate" means,  for any day, the rate per annum  (rounded
upwards,  if necessary,  to the nearest 0.01%) equal to the weighted  average of
the rates on overnight  Federal funds  transactions  with members of the Federal
Reserve  System  arranged by Federal  funds brokers on such day, as published by
the Federal  Reserve Bank of New York on the Business Day next  succeeding  such
day, provided that (a) if the day for which such rate is to be determined is not
a Business  Day, the Federal  Funds Rate for such day shall be such rate on such
transactions  on the next  preceding  Business  Day as so  published on the next
succeeding  Business  Day, and (b) if such rate is not so published on such next
succeeding Business Day, the Federal Funds Rate for any day shall be the average
rate charged to the  Administrative  Agent on such day on such  transactions  as
determined by the Administrative Agent.

         "Financial Hedge" means either (a) a swap, collar, floor, cap, or other
contract  which is intended to reduce or eliminate the risk of  fluctuations  in
interest rates, or (b) a foreign exchange,  currency hedging, commodity hedging,
or other  contract  which is intended to reduce or eliminate  the market risk of
holding  currency or a commodity  in either the cash or futures  markets,  which
Financial  Hedge  under  either  clause  (a) or clause  (b) is  entered  into by
Borrower with any Lender or an Affiliate of any Lender.

         "GAAP" means generally  accepted  accounting  principles,  applied on a
consistent basis, as set forth in Opinions of the Accounting Principles Board of
the American  Institute of Certified Public  Accountants and/or in statements of
the Financial Accounting Standards Board and/or their respective  successors and
which are applicable in the circumstances as of the date in question. Accounting
principles are applied on a "consistent  basis" when the  accounting  principles
applied in a current  period are  comparable  in all material  respects to those
accounting principles applied in a preceding period, except for changes required
by GAAP.  In the event of a change in GAAP,  Administrative  Agent and  Borrower
will  thereafter  negotiate  in good  faith  to  revise  any  covenants  of this
Agreement affected thereby in order to make such covenants  consistent with GAAP
then in effect.

         "Governmental  Authority" means any nation or government,  any state or
political subdivision thereof and any entity exercising executive,  legislative,
judicial,   regulatory,   or  administrative   functions  of  or  pertaining  to
government.

         "Governmental Authorization" shall mean any approval, consent, license,
permit, waiver, or other authorization issued, granted, given, or otherwise made
available by or under the authority of any Governmental Authority or pursuant to
any Legal Requirement.


<PAGE>


         "Guarantee"  by  any  Person  means  any   obligation,   contingent  or
otherwise,  of such Person directly or indirectly guaranteeing any Debt or other
obligation  of any other  Person and,  without  limiting the  generality  of the
foregoing, any obligation,  direct or indirect, contingent or otherwise, of such
Person (a) to purchase or pay (or  advance or supply  funds for the  purchase or
payment  of)  such  Debt or other  obligation  (whether  arising  by  virtue  of
partnership arrangements,  by agreement to keep-well, to purchase assets, goods,
securities  or services,  to  take-or-pay,  or to maintain  financial  statement
conditions or otherwise), or (b) entered into for the purpose of assuring in any
other manner the obligee of such Debt or other obligation of the payment thereof
or to protect the obligee against loss in respect thereof (in whole or in part),
provided that the term "Guarantee" shall not include endorsements for collection
or deposit in the ordinary course of business.  The term  "Guarantee"  used as a
verb has a corresponding meaning.

         "Guaranties" means,  collectively,  (a) the Guaranty  Agreements,  each
dated as of April 26,  1996,  executed by certain  Guarantors,  (b) the Consent,
Confirmation  and  Ratification  of Guaranty  Agreements,  dated as of March 31,
1997, executed by certain Guarantors,  (c) the Second Consent,  Confirmation and
Ratification  of  Guaranty  Agreements  dated as of April 20,  1998  executed by
certain Guarantors,  (d) the Consent,  Confirmation and Ratification of Guaranty
Agreements  dated as of April 20, 1998 executed by certain  Guarantors,  (e) the
Guaranty Agreement dated as of March 31, 1997 executed by Prostatherapies, Inc.,
(f) the Guaranty Agreements, each dated April 20, 1998 executed by each Excepted
Subsidiary and Executive Medial  Enterprises,  Inc., (g) the Guaranty  Agreement
dated  as of the  date  hereof  executed  by each  Guarantor;  certain  of which
Guaranty Agreements are in renewal,  amendment,  substitution and replacement of
the Guaranty Agreements executed by certain Guarantors under the Original Credit
Agreement  in favor of the  Agent and the  Lenders  under  the  Original  Credit
Agreement  and shall also include any other  guaranty  agreement  heretofore  or
hereafter  from time to time  executed by any  Guarantor  and  delivered  to the
Administrative Agent for the benefit of Lenders, as amended, restated,  renewed,
and substituted from time to time. "Guaranty" means any one of the Guaranties.

         "Guarantors"  means,  collectively,  all  Wholly-Owned  Subsidiaries of
Borrower,  now  owned  or  hereafter  acquired  or  formed,  including,  without
limitation,  the Subsidiaries  listed on Schedule 2, other than Prime Refractive
Management, L.L.C. "Guarantor" means any one of the Guarantors.

         "Guarantor Security Agreements" means (a) the Security Agreements, each
dated as of April 26,  1996,  executed by certain  Guarantors,  (b) the Consent,
Confirmation and Ratification of Guarantor Security Agreements dated as of March
31, 1997, executed by certain Guarantors,  (c) the Second Consent,  Confirmation
and  Ratification  of Guarantor  Security  Agreement dated as of April 20, 1998,
executed by certain Guarantors,  (d) the Consent,  Confirmation and Ratification
of  Guarantor  Security  Agreements  dated as of the date  hereof,  executed  by
certain  Guarantors,  (e) the  Security  Agreement  dated as of March 31,  1997,
executed by  Prostatherapies,  Inc., (f) the Guarantor Security Agreements dated
April 20, 1998  executed  by each  Excepted  Subsidiary  and  Executive  Medical
Enterprises,  Inc.,  (g) the  Security  Agreement  dated as of the  date  hereof
executed by each Guarantor each in favor of Administrative Agent for the benefit
of Lenders,  certain of which  Security  Agreements  are in renewal,  amendment,
restatement  and  substitution  of the Security  Agreements  executed by certain
Guarantors  under the Original Credit  Agreement in favor of the  Administrative
Agent, for the benefit of the Lenders under the Original Credit  Agreement,  and
shall also include any other  security  agreements  heretofore or hereafter from
time to time executed by any Guarantor and delivered to the Administrative Agent
for the benefit of Lenders, as amended, restated,  renewed, and substituted from
time to time.  "Guarantor  Security  Agreement"  means any one of the  Guarantor
Security Agreements.

         "Hazardous Material" means any substance,  product,  waste,  pollutant,
material,  chemical,  contaminant,  constituent,  or other  material which is or
becomes listed,  regulated, or addressed under any Environmental Law, including,
without limitation, asbestos, petroleum, and polychlorinated biphenyls.

     "Horizon  Acquisition"  means the  acquisition  by  Prime/BDR  Acquisition,
L.L.C. of 60% of the stock of Horizon Vision Center, Inc.


<PAGE>


         "Immediately-available"  means  that any cash or Cash  Equivalents  are
capable of being liquidated  (without premium,  penalty,  or restriction) within
180 days of any date of determination, are not subject to any Liens or claims of
third persons, and are unconditionally  available for payment of the Obligations
upon liquidation.

         "Interest Period" means, with respect to any Eurodollar  Advance,  each
period  commencing on the date such Advance is made or Converted from an Advance
of another Type or, in the case of each subsequent,  successive  Interest Period
applicable to a Eurodollar Advance,  the last day of the next preceding Interest
Period with respect to such Advance, and ending on the numerically corresponding
day in the first (1st),  second (2nd), third (3rd) or sixth (6th) calendar month
thereafter,  as Borrower  may select as  provided in Section 2.5 or 2.6,  except
that each such  Interest  Period which  commences on the last  Business Day of a
calendar  month (or on any day for which there is no  numerically  corresponding
day in the appropriate subsequent calendar month) shall end on the last Business
Day of the appropriate subsequent calendar month. Notwithstanding the foregoing:
(a) each  Interest  Period  which  would  otherwise  end on a day which is not a
Business  Day  shall  end on the  next  succeeding  Business  Day  (or,  if such
succeeding Business Day falls in the next succeeding calendar month, on the next
preceding  Business Day); (b) any Interest Period which would  otherwise  extend
beyond the Termination Date shall end on the Termination  Date; (c) no more than
six (6)  Interest  Periods  shall  be in  effect  at the same  time;  and (d) no
Interest  Period  shall have a duration  of less than one (1) month and,  if any
Interest Period would otherwise be a shorter period,  such Advances shall not be
available hereunder.

         "Issuance  Proceeds"  means  the net cash  proceeds  of (i) any sale or
issuance of Borrower's capital stock,  excluding any sale or issuance of capital
stock under Borrower's stock option plans, or (ii) the incurrence of any Debt of
the type described in  subsections  (a) and (b) of the definition of Debt (other
than the  Senior  Subordinated  Notes),  in each  case to the  extent  permitted
hereunder.

         "Lead Arranger" means Bank of America Securities L.L.C.

         "Legal Requirement" shall mean any federal,  state,  local,  municipal,
foreign,   international,   multinational,   or  other   administrative   order,
constitution,  law, ordinance, principle of common law, regulation,  statute, or
treaty as in effect on the date hereof.

         "Lenders"   mean,   on  any  date  of   determination,   the  financial
institutions named on Schedule 2.1 (as the same may be amended from time to time
by  Administrative  Agent to reflect the  assignments  made in  accordance  with
Section 13.6(b) of this  Agreement),  and subject to the terms and conditions of
this  Agreement,  and  their  respective  successors  and  assigns  (but not any
Participant  who is not  otherwise a party to this  Agreement);  provided  that,
solely for purposes of any  Collateral  Documents  and Section 12, and "Lenders"
shall  also  include  any  Lender  or  Affiliate  of a Lender  who is party to a
Financial Hedge with Borrower and their  respective  successors and assigns (for
purposes hereof, each Lender shall be deemed to have entered into this Agreement
for and on behalf of any Affiliate now or hereafter  party to a Financial  Hedge
with Borrower).

         "Lien" means any lien, mortgage, security interest, tax lien, financing
statement, pledge, charge, hypothecation,  assignment,  preference, priority, or
other  encumbrance  of  any  kind  or  nature  whatsoever  (including,   without
limitation, any conditional sale or title retention agreement),  whether arising
by contract, operation of law, or otherwise.

         "Litho" means Lithotripters, Inc., a North Carolina corporation.



<PAGE>


         "Loan" means all Advances with respect to the Commitment,  evidenced by
the Notes.

         "Loan Documents" means this Agreement,  the Notes, the Guaranties,  the
Borrower  Security  Agreement,  the Guarantor  Security  Agreements,  the Pledge
Agreements, any Financial Hedge documents, and all other instruments, documents,
and  agreements  executed and delivered  pursuant to or in connection  with this
Agreement,  as such  instruments,  documents,  and  agreements  may be  amended,
modified, renewed, extended, or supplemented from time to time.

         "Material  Subsidiary" means, as of any date, (a) any Subsidiary which,
together with its  Subsidiaries,  accounts for three percent (3%) or more of the
Company's  consolidated  gross  revenues or assets,  or (b) any  combination  of
Subsidiaries which, together with their Subsidiaries,  account for seven percent
(7%) or more of the Company's  consolidated  gross  revenues or assets,  in each
case on a consolidated basis (but without elimination of any minority interests)
as of and for the most  recent  fiscal  quarter  for which such  information  is
available. "Material Subsidiaries" means all of the Material Subsidiaries.

         "Maximum Rate" means,  at any time and with respect to any Lender,  the
maximum  rate of  interest  under  applicable  law that such  Lender  may charge
Borrower.  The  Maximum  Rate shall be  calculated  in a manner  that takes into
account  any and all fees,  payments,  and other  charges in respect of the Loan
Documents  that  constitute  interest under  applicable  law. Each change in any
interest rate provided for herein based upon the Maximum Rate  resulting  from a
change in the Maximum Rate shall take effect  without  notice to Borrower at the
time of such change in the Maximum Rate.

         "Multiemployer  Plan" means a multiemployer  plan as defined in Section
3(37) of ERISA to which  contributions  have been made by  Borrower or any ERISA
Affiliate of Borrower and which is covered by Title IV of ERISA.

         "Net Total Funded Debt" means,  as of any date, the sum of: (a) Debt of
the Companies;  less (b) the amount of any  Immediately-available  cash and Cash
Equivalents held by the Companies in excess of $8,000,000 in the aggregate; plus
(c) the  amount  of all  cash  and  cash  equivalents  held by any  Company  for
distribution to any partners or other owners of equity interests (other than any
Company) in any Partnership.

         "Net Total  Funded Debt to EBITDA  Ratio"  means,  as of any date,  the
ratio of (a) the aggregate  amount of Net Total Funded Debt  (without  deduction
for any minority interests), outstanding as of such date, to (b) Adjusted EBITDA
of the  Companies,  for the four (4) fiscal quarter period ending on the date of
determination.

         "Note"   means  a   revolving   credit  note   executed  by   Borrower,
substantially  in the form of  Exhibit C,  payable  to each  Lender in an amount
equal to such  Lender's  Commitment,  as the same may be amended,  supplemented,
modified or restated from time to time, evidencing the obligation of Borrower to
repay the Loan, and all renewals,  modifications and extensions thereof. "Notes"
means all of the Notes of the Lenders.

         "Obligated  Party"  means any  Person  who is or  becomes  party to any
agreement that  guarantees or secures payment and performance of the Obligations
or any part thereof.


<PAGE>


         "Obligations" means all obligations,  indebtedness,  and liabilities of
Borrower to the Agents and the Lenders,  or any of them, arising pursuant to any
of the Loan  Documents,  now  existing or  hereafter  arising,  whether  direct,
indirect,  related,  unrelated,  fixed,  contingent,  liquidated,  unliquidated,
joint,  several, or joint and several, and all interest accruing thereon and all
attorneys'  fees and other  expenses  incurred in the  enforcement or collection
thereof;  provided that, all references to the  "Obligations"  in the Collateral
Documents, and in Section 12, shall, in addition to the foregoing,  also include
all present  and future  indebtedness,  liabilities,  and  obligations  (and all
renewals and  extensions  thereof or any part thereof) now or hereafter  owed to
any Lender or any Affiliate of a Lender  arising from, by virtue of, or pursuant
to any Financial Hedge entered into by any Company.

         "Original Credit Agreement" has the meaning specified in the recitals.

         "Partnerships"  means the partnerships and limited liability  companies
in which  Borrower or any  Subsidiary  now owns or  hereafter  acquires  general
and/or limited partnership interests or membership interests, including, without
limitation,   the   partnerships   and  other  Persons  listed  on  Schedule  3.
"Partnership" means any one of the Partnerships,  and shall also include any non
Wholly-Owned Subsidiary of Prime RVC or Prime Refractive Management, L.L.C.

         "Payment  Date" means (a) with respect to Alternate  Base Rate Advances
and the commitment fees payable  pursuant to Section  2.8(a),  the last Business
Day of each April, July,  October and January,  commencing January 31, 2000, and
(b) with respect to Eurodollar Advances, the last day of the respective Interest
Period therefor,  provided that if any Interest Period is greater than three (3)
months,  then accrued interest shall also be due and payable on the date that is
three (3) months after the commencement of such Interest Period.

         "PBGC" means the Pension  Benefit  Guaranty  Corporation  or any entity
succeeding to all or any of its functions under ERISA.

         "Permitted  Acquisition" means an Acquisition by Borrower or any of the
Guarantors  with respect to which each of the  following  conditions  shall have
been satisfied:

                  (a) the  Acquisition  by  Borrower or such  Guarantor  is of a
         business,  assets,  or Person (as  applicable,  the "Target")  which is
         engaged  in  substantially   the  same  lithotripsy   business  as  the
         lithotripsy  business  conducted  by Borrower or such  Guarantor on the
         date hereof, or any other business reasonably related thereto;

                  (b) as of the closing of such Acquisition, the Acquisition has
         been approved by the board of directors or other  applicable  governing
         body of the  Target  and the  Person  from  which  the  Target is to be
         acquired;

               (c) prior to the closing of such Acquisition,  the Target and the
          Person from which the Target is to be acquired must be Solvent;

                  (d) as of the closing of such Acquisition, after giving effect
         to such  Acquisition,  Borrower or the Guarantor  that is the acquiring
         party must be Solvent and the Companies,  on a consolidated basis, must
         be Solvent;

                  (e) as of the closing of such Acquisition, after giving effect
         to such  Acquisition,  no Default  shall exist or occur as a result of,
         and after giving effect to, such Acquisition;


<PAGE>


                  (f)  the  aggregate   purchase  price  with  respect  to  such
         Acquisition  does not  exceed  five (5)  times  EBITDA  of the  Target,
         subject to  adjustments  acceptable to the  Administrative  Agent where
         less  than  all of the  business,  assets  or stock  of the  Target  is
         acquired,  pursuant to the Acquisition for the four (4) fiscal quarters
         ending on the most  recently  ended fiscal  period prior to the date of
         such Acquisition;

                  (g) the aggregate nonstock  consideration for such Acquisition
         does  not  exceed   $20,000,000.00   (other  than  the  Acquisition  of
         additional ownership interests in the Partnerships in which Borrower or
         a Guarantor is, as if the date hereof,  the general partner or managing
         member)  and the  aggregate  cash  consideration  for all  Acquisitions
         (other than the  Acquisition of additional  ownership  interests of the
         Partnerships  in  which  Borrower  or a  Guarantor  is,  as of the date
         hereof,  the general partner or managing member) during the immediately
         preceding twelve (12) month period  (including such  Acquisition)  does
         not exceed $40,000,000.00;

                  (h) not less than 15 Business Days prior to the closing of any
         Acquisition,  the  Administrative  Agent shall have  received pro forma
         financial  statements of the  Companies (as if the business,  assets or
         Person  acquired  had been  acquired  since the first  (1st) day of the
         period for which such pro forma financial  statements are delivered and
         had been  managed  and  conducted  in  accordance  with the  Borrower's
         standard business  practices) for the prior four (4) fiscal quarters of
         Borrower and the Companies;

               (i)  as  of  the  closing  of  such  Acquisition,  Borrower  or a
          Guarantor shall Control the Target;

               (j) if the  Target is to be an  After-Acquired  Subsidiary,  then
          Borrower  shall have complied with the terms and  conditions set forth
          in Section 8.13;

                  (k) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Acquisition,  which  could  reasonably  be  expected to have a material
         adverse effect on the Target Company or the Borrower; and

                  (l) the Administrative  Agent has received a certificate dated
         on or  immediately  prior to the date of  Acquisition,  executed by the
         President  or  a  Vice  President  of  Borrower   confirming  that  all
         representations and warranties set forth in the Loan Documents continue
         to be true and correct in all material  respects  immediately  prior to
         and  after  giving  effect  to  the  Permitted   Acquisition   and  the
         transactions  contemplated  thereby, and setting forth the calculations
         supporting compliance with the limitations prescribed herein.

         "Permitted Other Business Acquisition" means an acquisition by Borrower
or any of the Guarantors with respect to which each of the following  conditions
shall have been satisfied:

                  (a) the  acquisition  by  Borrower or such  Guarantor  is of a
         business,  assets,  or Person (as  applicable,  the "Target")  which is
         engaged  in  substantially  the  same  physician  practice  management,
         prostatherapy,   or   servicing   tractor/trailers   business  as  such
         businesses are conducted by Borrower or any Company on the date hereof,
         or any other business reasonably related thereto;


<PAGE>


                  (b)  as of  the  closing  of  such  Permitted  Other  Business
         Acquisition, the Permitted Other Business Acquisition has been approved
         by the board of directors  or other  applicable  governing  body of the
         Target and the Person from which the Target is to be acquired;

               (c)  prior  to the  closing  of  such  Permitted  Other  Business
          Acquisition,  the Target and the Person from which the Target is to be
          acquired must be Solvent;

                  (d)  as of  the  closing  of  such  Permitted  Other  Business
         Acquisition,  after  giving  effect to such  Permitted  Other  Business
         Acquisition, Borrower or the Guarantor that is the acquiring party must
         be Solvent and the Companies, on a consolidated basis, must be Solvent;

                  (e)  as of  the  closing  of  such  Permitted  Other  Business
         Acquisition,  after  giving  effect to such  Permitted  Other  Business
         Acquisition,  no Default shall exist or occur as a result of, and after
         giving effect to, such Permitted Other Business Acquisition;

                  (f)  the  aggregate   purchase  price  with  respect  to  such
         Permitted  Other  Business  Acquisition  does not exceed five (5) times
         EBITDA  of  the  Target,  subject  to  adjustments  acceptable  to  the
         Administrative  Agent  where less than all of the  business,  assets or
         stock of the  Target  is  acquired,  pursuant  to the  Permitted  Other
         Business  Acquisition  for the four (4) fiscal  quarters  ending on the
         most recently  ended fiscal period prior to the date of such  Permitted
         Other Business Acquisition;

                  (g) the  aggregate  nonstock  consideration  for all Permitted
         Other  Business   Acquisitions   (other  than  the  acquisition  of  AK
         Associates,  which has been  previously  consented  to) does not exceed
         $5,000,000;

                  (h) not less than 15 Business Days prior to the closing of any
         Permitted Other Business  Acquisition,  the Administrative  Agent shall
         have  received pro forma  financial  statements of the Companies (as if
         the business,  assets or Person  acquired had been  acquired  since the
         first  (1st)  day of the  period  for which  such pro  forma  financial
         statements  are  delivered  and  had  been  managed  and  conducted  in
         accordance  with the Borrower's  standard  business  practices) for the
         prior four (4) fiscal quarters of Borrower and the Companies;

               (i) if the  Target is to be an  After-Acquired  Subsidiary,  then
          Borrower  shall have complied with the terms and  conditions set forth
          in Section 8.13;

                  (j) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Permitted  Other  Business  Acquisition,   which  could  reasonably  be
         expected to have a material adverse effect on the Target Company or the
         Borrower; and

                  (k) the Administrative  Agent has received a certificate dated
         on or  immediately  prior  to the  date  of  Permitted  Other  Business
         Acquisition,  executed by the President or a Vice President of Borrower
         confirming  that all  representations  and  warranties set forth in the
         Loan Documents continue to be true and correct in all material respects
         immediately  prior to and after giving  effect to the  Permitted  Other
         Business  Acquisition and the transactions  contemplated  thereby,  and
         setting  forth  the   calculations   supporting   compliance  with  the
         limitations prescribed herein.


<PAGE>


         The loan  described  in  Sections  9.1A(h)  and 9.2(h)  hereof  made by
Borrower  shall not be included in the  calculation  of the  aggregate  nonstock
consideration  for all Permitted Other Business  Acquisitions.  No repurchase or
redemption  of  Borrower's  capital  stock by Borrower or a  Guarantor,  whether
through  issuance and  performance of a put agreement,  or otherwise  shall be a
Permitted Other Business Acquisition.

         "Permitted Passive  Investment" means an acquisition by Borrower or any
of  the  Guarantors,  in one  transaction  or in a  series  of  transactions  of
partnership, stock, or other interests of a Person ("Equity Interests") which is
not an Acquisition and does not permit Borrower or any Guarantor to Control such
Person, with respect to which each of the following conditions have been met:

                  (a) the acquisition by Borrower or such Guarantor is of Equity
         Interests  of a Person  (the  "Passive  Target")  which is  engaged  in
         substantially the same lithotripsy business as the lithotripsy business
         conducted  by Borrower or such  Guarantor  on the date  hereof,  or any
         other lithotripsy business reasonably related thereto;

                  (b) as of the closing of such  Permitted  Passive  Investment,
         the  acquisition  has been  approved by the board of directors or other
         applicable  governing  body of the  Passive  Target and the Person from
         which the Equity Interests are to be acquired;

               (c) prior to the closing of such acquisition,  the Passive Target
          and the Person from which the Equity Interests are to be acquired must
          be Solvent;

                  (d) as of the closing of such  Permitted  Passive  Investment,
         after giving effect to such Permitted Passive  Investment,  Borrower or
         the  Guarantor  that is the  acquiring  party must be  Solvent  and the
         Companies, on a consolidated basis, must be Solvent;

                  (e) as of the closing of such  Permitted  Passive  Investment,
         after giving effect to such Permitted  Passive  Investment,  no Default
         shall exist or occur as a result of, and after  giving  effect to, such
         Permitted Passive Investment;

                  (f) the aggregate  acquisition  price of any Permitted Passive
         Investment,  together  with  the  original  purchase  price of all then
         existing  Permitted Passive  Investments of Borrower and its Guarantors
         (excluding,  however,  any prior  Permitted  Passive  Investment  which
         Borrower or any Guarantor then Controls) as of the date of consummation
         of the Permitted Passive Investment,  does not exceed the lesser of (i)
         twenty percent (20%) of Total Equity or (ii) $50,000,000;

                  (g) not less than 30 Business Days prior to the closing of any
         Permitted  Passive  Investment,  the  Administrative  Agent  shall have
         received a certificate setting forth compliance with condition (f), set
         forth above;

                  (h) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Permitted  Passive  Investment,  which could  reasonably be expected to
         have a material  adverse  effect on the Target Company or the Borrower;
         and


<PAGE>


                  (i) the Administrative  Agent has received a certificate dated
         on  or  immediately   prior  to  the  date  of  the  Permitted  Passive
         Investment,  executed by the President or a Vice  President of Borrower
         confirming  that all  representations  and  warranties set forth in the
         Loan Documents continue to be true and correct in all material respects
         immediately  prior to and after giving effect to the Permitted  Passive
         Investment and the transactions contemplated thereby, and setting forth
         the calculations  supporting compliance with the limitations prescribed
         herein.

No  repurchase  or  redemption  of  Borrower's  capital  stock by  Borrower or a
Guarantor,  whether  through  issuance and  performance of a put  agreement,  or
otherwise, shall be a Permitted Passive Investment.

               "Permitted  Refractive   Acquisition"  means  an  Acquisition  by
          Borrower, any Guarantor, Prime Refractive Management, L.L.C., or Prime
          Refractive,  L.L.C.,  with  respect  to  which  each of the  following
          conditions shall have been satisfied:

               (a) the  acquisition by Borrower,  Guarantors,  Prime  Refractive
          Management, L.L.C., or Prime Refractive, L.L.C. is of a Target Company
          which is engaged in the businesses of correcting  refractive  error of
          the eye, or any other business reasonably related thereto;

                  (b)  as  of  the   closing   of  such   Permitted   Refractive
         Acquisition,  the Permitted Refractive Acquisition has been approved by
         the board of directors or other applicable governing body of the Target
         Company and the Person from which the Target Company is to be acquired;

                  (c) prior to or at  closing,  the  closing  of such  Permitted
         Refractive  Acquisition,  the Target  Company and the Person from which
         the Target Company is to be acquired must be Solvent;

               (d) as of the closing of such Permitted  Refractive  Acquisition,
          after  giving  effect  to  such  Permitted   Refractive   Acquisition,
          Borrower,  the Guarantor that is the acquiring party, Prime Refractive
          Management,  L.L.C.,  or Prime Refractive  L.L.C., as the case may be,
          must be Solvent and the Companies,  on a consolidated  basis,  must be
          Solvent;

                  (e)  as  of  the   closing   of  such   Permitted   Refractive
         Acquisition,   after  giving  effect  to  such   Permitted   Refractive
         Acquisition,  no Default shall exist or occur as a result of, and after
         giving effect to, such Permitted Refractive Acquisition;

                  (f)  the  aggregate   purchase  price  with  respect  to  such
         Permitted  Refractive  Acquisition does not exceed six (6) times EBITDA
         of  the  Target  Company,  subject  to  adjustments  acceptable  to the
         Administrative  Agent  where less than all of the  business,  assets or
         stock of the Target  Company is  acquired,  pursuant  to the  Permitted
         Refractive  Acquisition  for the four (4) fiscal quarters ending on the
         most recently  ended fiscal period prior to the date of such  Permitted
         Refractive Acquisition;

                  (g) the  aggregate  nonstock  consideration  for any Permitted
         Refractive Acquisition (including, without limitation, any financing of
         interests  acquired  by  LASIK  Investors,   L.L.C.,  and  Consolidated
         Earn-Out Indebtedness  reasonably estimated by Administrative Agent and
         Borrower)  does not exceed  $10,000,000.00  and the aggregate  nonstock
         consideration  for  all  Permitted   Refractive   Acquisitions  in  the
         aggregate  financed  with  Advances   hereunder,   advances  under  the
         Advancing Term Loan Facility,  and Consolidated Earn-Out  Indebtedness,
         does not exceed $65,000,000;


<PAGE>


                  (h) not less than 15 Business Days prior to the closing of any
         Permitted Refractive  Acquisition,  the Administrative Agent shall have
         received pro forma  financial  statements  of the  Companies (as if the
         business,  assets or Person  acquired had been acquired since the first
         (1st) day of the period for which such pro forma  financial  statements
         are delivered and had been managed and conducted in accordance with the
         Borrower's  standard business  practices) for the prior four (4) fiscal
         quarters of Borrower and the Companies;

               (i) if the Target Company is to be an After-Acquired  Subsidiary,
          then Borrower  shall have complied with the terms and  conditions  set
          forth in Section 8.13;

                  (j) review by a third party  acceptable to the  Administrative
         Agent of Borrower's due diligence  process and procedures as related to
         Permitted Refractive  Acquisitions,  acceptable to Administrative Agent
         and Lenders;

                  (k) with respect to any Permitted Refractive Acquisition where
         the aggregate nonstock consideration is $10,000,000 or less (including,
         without  limitation,  any  financing  of  interests  acquired  by LASIK
         Investors,  L.L.C. and Consolidated  Earn-Out  Indebtedness  reasonably
         estimated by  Administrative  Agent and  Borrower),  the Target Company
         must, at a minimum,  provide company prepared financial  statements for
         the immediately  preceding four fiscal quarters  prepared in accordance
         with the due diligence procedures approved in (j) above;

               (l) the Target Company or other  business  segment being acquired
          must have positive pro forma trailing twelve month EBITDA;

               (m) the capital and  ownership  structure  of the Target  Company
          (after giving effect to the Permitted Refractive Acquisition) shall be
          satisfactory to the Administrative Agent;

                  (n) the absence of action, suit, investigation,  or proceeding
         pending  or  threatened  in any  court  or  before  any  arbitrator  or
         governmental  authority that affects the Target Company or the proposed
         Permitted Refractive Acquisition, which could reasonably be expected to
         have a material adverse effect on the Target Company or the Borrower;

                  (o) receipt of all governmental,  shareholder, and third party
         consents and approvals  necessary or desirable in  connection  with the
         acquisition  of the Target  Company and all  transactions  contemplated
         thereby;

                  (p) the Administrative  Agent has received a certificate dated
         on  or   immediately   prior  to  the  date  of  Permitted   Refractive
         Acquisition,  executed by the President or a Vice President of Borrower
         confirming  that all  representations  and  warranties set forth in the
         Loan Documents continue to be true and correct in all material respects
         immediately   prior  to  and  after  giving  effect  to  the  Permitted
         Refractive  Acquisition and the transactions  contemplated thereby, and
         setting  forth  the   calculations   supporting   compliance  with  the
         limitations prescribed herein; and

                  (q) Borrower or one of its Subsidiaries  must own at least 51%
         of the equity or membership interests in and Control the Target Company
         upon completion of the Permitted Refractive Acquisition.

         "Person"   means   any   individual,   corporation,   business   trust,
association,  company,  partnership,  joint venture,  Governmental Authority, or
other entity.


<PAGE>


         "Plan"  means  any  employee  benefit  or  other  plan  established  or
maintained  by Borrower or any ERISA  Affiliate of Borrower and which is covered
by Title IV of ERISA.

         "Pledge  Agreements" means (a) the Pledge Agreements,  each dated as of
April 26, 1996,  executed by Borrower and each Subsidiary of Borrower that owned
general and/or limited partnership interests in the Partnerships in favor of the
Administrative  Agent,  for the  benefit  of the  Lenders,  as the  same  may be
amended,  supplemented or modified from time to time, including (b) the Consent,
Confirmation  and  Ratification of Pledge and Security  Agreements,  dated as of
March 31, 1997, (c) the Second Consent,  Confirmation and Ratification of Pledge
and Security Agreements dated as April 20, 1998, and (d) the Pledge and Security
Agreements dated as of the date hereof,  and shall also include any other pledge
agreement  heretofore or hereafter  from time to time executed by any Person and
delivered  to  Administrative  Agent for the  benefit of  Lenders,  as  amended,
restated,  renewed,  and substituted from time to time. "Pledge Agreement" means
any one of the Pledge Agreements.

         "Pledgors"  means each of the  pledgors  of  partnership  interests  or
Assigned Rights (as defined in the applicable  Pledge  Agreement)  pursuant to a
Pledge Agreement. "Pledgor" means any one of the Pledgors.

     "PMOI" means Prime Medical Operating, Inc., a Delaware corporation, and its
permitted successors and assigns.

     "Prime  RVC"  means  Prime  RVC,  Inc.,  a  Delaware  corporation,  and its
permitted successors and assigns.

         "Principal  Office"  means  the  office  of the  Administrative  Agent,
presently located at 901 Main Street, 7th Floor, Dallas, Texas 75202.

     "Prohibited  Transaction" means any transaction set forth in Section 406 of
ERISA or Section 4975 of the Code.

         "Regulation  D" means  Regulation  D of the Board of  Governors  of the
Federal Reserve System as the same may be amended or  supplemented  from time to
time.

         "Regulatory Change" means, with respect to any Lender, any change after
the date of this Agreement in United States  federal,  state, or foreign laws or
regulations  (including  Regulation D) or the adoption or making after such date
of any  interpretations,  directives,  or requests  applying to a class of banks
including such Lender of or under any United States  federal,  state, or foreign
laws or  regulations  (whether  or not  having the force of law) by any court or
governmental  or  monetary   authority   charged  with  the   interpretation  or
administration thereof.

         "Release"  means,  as to any  Person,  any  release,  spill,  emission,
leaking,  pumping,  injection,  deposit,  disposal,  disbursement,  leaching, or
migration of Hazardous  Materials into the indoor or outdoor environment or into
or out of property  owned by such Person,  including,  without  limitation,  the
movement of Hazardous  Materials  through or in the air,  soil,  surface  water,
ground water, or property.


<PAGE>


         "Remedial  Action" means all actions  required to (a) clean up, remove,
treat,  or  otherwise  address  Hazardous  Materials  in the  indoor or  outdoor
environment,  (b)  prevent  the  Release or threat of Release  or  minimize  the
further  Release of Hazardous  Materials so that they do not migrate or endanger
or  threaten  to  endanger  public  health or  welfare  or the indoor or outdoor
environment,   or  (c)  perform  pre-remedial  studies  and  investigations  and
post-remedial monitoring and care.

         "Reportable Event" means any of the events set forth in Section 4043 of
ERISA.

         "Required  Lenders"  means,  as of any date, any combination of Lenders
(other than any Defaulting Lenders) who collectively hold sixty percent (60%) of
the sum of the  Commitments  (other than of any Defaulting  Lenders),  or if the
Commitments  shall have been terminated,  then of the aggregate unpaid principal
amount of the Notes (other than of any Defaulting Lenders).

         "Reserve  Requirement"  means,  for  any  Eurodollar  Advance  for  any
Interest  Period  therefor,  the average rate at which  reserves  (including any
marginal,  supplemental  or emergency  reserves)  are required to be  maintained
during such Interest Period under  Regulation D by each Lender on its portion of
such  Advance  against  "Eurocurrency  Liabilities"  as  such  term  is  used in
Regulation  D.  Without  limiting  the  effect  of the  foregoing,  the  Reserve
Requirement  shall  reflect any other  reserves  required to be  maintained by a
Lender  by  reason  of  any  Regulatory  Change  against  (i)  any  category  of
liabilities   which  includes  deposits  by  reference  to  which  the  Adjusted
Eurodollar  Rate is to be  determined,  or (ii) any  category of  extensions  of
credit or other assets which include Eurodollar Advances.

         "RICO" means the Racketeer  Influenced and Corrupt  Organization Act of
1970, as amended from time to time.

         "Senior Net Debt" means,  as of any date,  all Net Total Funded Debt of
the Companies which is not Subordinated Debt.

         "Senior Net Funded Debt to EBITDA  Ratio"  means,  as of any date,  the
ratio of (a) the aggregate  amount of Senior Net Debt of the Companies  (without
deduction for any minority  interests),  as of such date, to (b) Adjusted EBITDA
of the  Companies,  for the four (4) fiscal quarter period ending on the date of
determination  (including  on a  pro  forma  basis  any  Permitted  Acquisition,
Permitted Other Business Acquisition or Permitted Refractive Acquisition).

         "Senior  Subordinated  Indenture"  means that certain  Trust  Indenture
dated as of March 24,  1998  between  Borrower  and State  Street Bank and Trust
Company, as Trustee, and any trust indenture entered into in connection with the
Exchange Notes.

         "Senior Subordinated Notes" means those certain $100,000,000  aggregate
principal amount Senior  Subordinated  Notes issued by Borrower  pursuant to the
Senior  Subordinated  Indenture,  due April 1, 2008, and the Exchange  Notes, if
issued.

         "Solvent"  means,  with  respect  to any  Person,  that on the  date of
determination  (a) the fair market value of its assets is greater than the total
amount of liabilities,  including, without limitation, contingent liabilities of
such Person which would be required to be included on the balance  sheet of such
Person or disclosed in the  financial  statements  of such Person in  accordance
with GAAP,  (b) the present fair  salable  value of the assets of such Person is
not less than the amount that will be required to pay the probable  liability of
such Person on its debts as they become  absolute and  matured,  (c) such Person
does not intend to, and does  believe that it will,  incur debts or  liabilities
beyond such Person's  ability to pay as such debts and liabilities  mature,  and
(d) such Person is not engaged in business or transactions,  and is not about to
engage in business or  transactions,  for which its assets would  constitute  an
unreasonably small capital.


<PAGE>


         "Subordinated Debt" means the Senior Subordinated Notes.

         "Subsidiary"  means,  with  respect  to any  Person,  any  corporation,
partnership,  association,  or other business entity (a) of which  securities or
other  ownership  interests  representing  more than fifty  percent (50%) of the
equity or more than fifty  percent  (50%) of the  ordinary  voting power or more
than fifty  percent  (50%) of the general  partnership  interests or  membership
interests are, at the time any determination is made, owned,  Controlled or held
by such Person, or (b) that is, at the time any determination is made, otherwise
Controlled by one or more  Subsidiaries of such Person or by such Person and one
or more Subsidiaries of such Person.

         "Target  Company"  means any  Person  that has been or may be  acquired
pursuant to an Acquisition permitted hereunder.

         "Termination  Date"  means  1:00 p.m.  Dallas,  Texas time on April 21,
2003,  or such  earlier  date and time on which  the  Commitments  terminate  as
provided in this Agreement.

         "Total  Equity"  means,  at  any  particular  time,  the  sum  of:  (a)
Consolidated  Net Worth,  plus (b) outstanding  principal amount of Subordinated
Debt.

         "Total Net Funded  Debt to EBITDA  Ratio"  means,  as of any date,  the
ratio of (a) the  aggregate  outstanding  amount  of Net  Funded  Debt  (without
deduction for any minority  interests),  as of such date, to (b) Adjusted EBITDA
of the  Companies for the four (4) fiscal  quarter  period ending on the date of
determination  (including  on a pro forma basis any Permitted  Acquisition,  any
Permitted Other Business Acquisition, or Permitted Refractive Acquisition).

     "Type"  means any type of Advance  (i.e.,  Alternate  Base Rate  Advance or
Eurodollar Advance).

         "UCC"  means the Uniform  Commercial  Code as in effect in the State of
Texas or other applicable jurisdiction, as amended.

         "Wholly-Owned  Subsidiaries"  means,  as of any date, all  Subsidiaries
that are  wholly-owned  by Borrower or a  wholly-owned  Subsidiary  of Borrower.
"Wholly-Owned Subsidiary" means any one of the Wholly-Owned Subsidiaries.

         Section 1.3 Other Definitional Provisions. All definitions contained in
this  Agreement  are equally  applicable to the singular and plural forms of the
terms  defined.  The words  "hereof,"  "herein,"  and  "hereunder"  and words of
similar import  referring to this  Agreement  refer to this Agreement as a whole
and  not to  any  particular  provision  of  this  Agreement.  Unless  otherwise
specified, all Article, Section, Exhibit and Schedule references pertain to this
Agreement.  All  accounting  terms  not  specifically  defined  herein  shall be
construed  in  accordance  with  GAAP.  All  financial   covenants  and  related
definitions  relating to the Companies  shall,  unless otherwise  indicated,  be
determined  after  deduction  of  any  minority  interests,  provided  that  all
references to "Debt" shall  include all Debt without  deduction for any minority
interests.  Terms used  herein  that are  defined in the UCC,  unless  otherwise
defined herein, shall have the meanings specified in the UCC.


<PAGE>


                             ARTICLE II -- ADVANCES

         Section 2.1       Commitments.

         (a) Revolving Credit  Commitments.  Subject to the terms and conditions
of this  Agreement,  each  Lender  hereby  severally  agrees to make one or more
Advances to Borrower  from time to time from the date hereof to the  Termination
Date in an  aggregate  principal  amount at any time  outstanding  up to but not
exceeding the amount of such Lender's  Commitment as then in effect.  Subject to
the foregoing limitations, and the other terms and provisions of this Agreement,
Borrower may borrow, repay, and reborrow hereunder the amount of the Commitments
by means of Eurodollar Advances or Alternate Base Rate Advances.

         (b) Optional  Reduction and Termination of Commitments.  Borrower shall
have the right to terminate in whole or reduce in part the unused portion of the
Commitments  upon at least three (3) Business  Days' prior written notice (which
notice  shall  be  irrevocable)  to  the  Administrative  Agent  specifying  the
effective  date thereof,  whether a termination  or reduction is being made, and
the amount of any partial reduction,  provided that each partial reduction shall
be in the amount of  $1,000,000.00  or a greater  integral  multiple thereof and
Borrower shall  simultaneously  prepay the amount by which the unpaid  principal
amount of the Notes exceeds the Commitments (after giving effect to such notice)
plus accrued and unpaid interest on the principal amount so prepaid.  No portion
of the Commitments may be reinstated after it has been terminated or reduced.

         Section 2.2 Notes.  The obligation of Borrower to repay each Lender for
Advances  made by such Lender  pursuant  to such  Lender's  Commitment,  and all
interest thereon,  shall be evidenced by a Note dated the date hereof,  executed
by Borrower  and payable to the order of such Lender in the  original  principal
amount of such Lender's  Commitment.  Upon receipt of an affidavit of an officer
of any Lender to the loss, theft, destruction or mutilation of any Note, and, in
the case of any such loss, theft,  destruction or mutilation,  upon cancellation
of such Note,  Borrower will issue, in lieu thereof,  a replacement  note in the
same principal amount thereof and otherwise of like tenor.

     Section 2.3  Repayment of Advances.  Borrower  shall repay the  outstanding
principal amount of the Notes on the Termination Date.

         Section 2.4 Interest. The unpaid principal amount of all Advances shall
bear interest at a varying rate per annum equal from day to day to the lesser of
(a) the Maximum Rate, or (b) the Applicable  Rate. If at any time the Applicable
Rate for any Advance shall exceed the Maximum Rate, thereby causing the interest
accruing on such Advance to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate for such Advance shall not reduce the rate of
interest on such Advance  below the Maximum Rate until the  aggregate  amount of
interest  accrued on such Advance equals the aggregate  amount of interest which
would have accrued on such Advance if the Applicable  Rate had at all times been
in effect.  Accrued and unpaid interest on the Advances shall be due and payable
on each Payment Date and on the Termination Date. Notwithstanding the foregoing,
any outstanding principal of any Advance and (to the fullest extent permitted by
law) any other amount payable by Borrower under this Agreement or any other Loan
Document  that is not paid in full  when due  (whether  at stated  maturity,  by
acceleration,  or  otherwise)  shall bear  interest at the Default  Rate for the
period from and  including  the due date thereof to but  excluding  the date the
same is paid in full. Interest payable at the Default Rate shall be payable from
time to time on demand.


<PAGE>


         Section 2.5       Borrowing Procedure.

         (a) Loan. Borrower shall give the Administrative  Agent notice by means
of an Advance  Request  Form of each  requested  Advance  under the  Commitments
hereunder at least three (3)  Business  Days before the  requested  date of each
Eurodollar  Advance (and at least one (1) Business Day before the requested date
of each Alternate Base Rate Advance), specifying: (a) the requested date of such
Advance (which shall be a Business Day); (b) the amount of such Advance; and (c)
the duration of the Interest Period for such Advance (if a Eurodollar  Advance).
The  Administrative  Agent at its  option  may accept  telephonic  requests  for
Advances  under  the  Commitments,  provided  that  such  acceptance  shall  not
constitute  a waiver  of the  Administrative  Agent's  right to  delivery  of an
Advance  Request  Form  in  connection   with  subsequent   Advances  under  the
Commitments.  Any  telephonic  request for an Advance under the  Commitments  by
Borrower  shall be promptly  confirmed  by  submission  of a properly  completed
Advance  Request  Form to the  Administrative  Agent.  Each  Advance  under  the
Commitments shall be in a minimum principal amount of $1,000,000.00 or a greater
integral  multiple  thereof,  provided  that if such  Advance  equals the entire
remaining  unfunded  portion of the Commitments,  it may be for any amount.  The
aggregate  principal  amount of  Eurodollar  Advances  having the same  Interest
Period shall be at least equal to $2,500,000.00  or a greater integral  multiple
of  $500,000.00.  All notices under this Section 2.5(a) shall be irrevocable and
shall be given not later than 11:00 a.m. Dallas,  Texas time on the day which is
not less than the number of Business Days specified above for such notice.

         (b) Generally.  The  Administrative  Agent shall  promptly  notify each
Lender of the contents of each Advance  Request Form.  Not later than 11:00 a.m.
Dallas, Texas time on the date specified for each Advance hereunder, each Lender
will make  available  to the  Administrative  Agent at the  Principal  Office in
immediately available funds, for the account of Borrower,  its pro rata share of
each Advance. After the Administrative Agent's receipt of such funds and subject
to the other terms and conditions of this Agreement,  the  Administrative  Agent
will  make each  Advance  available  to  Borrower  by  depositing  the same,  in
immediately  available funds, in a deposit account of Borrower maintained at the
Documentation Agent.

         Section 2.6       Continuations; Conversions.

         (a) Continuations. Borrower shall have the right to Continue Eurodollar
Advances by giving the Administrative  Agent written notice specifying:  (i) the
Continuation date; (ii) the amount of the Advance to be Continued; and (iii) the
duration of the  Interest  Period  applicable  thereto,  which  notice  shall be
irrevocable  and must be given by  Borrower  not later than  11:00 a.m.  Dallas,
Texas time at least three (3) Business Days before each such  Continuation.  The
Administrative  Agent shall promptly  notify each Lender of the contents of each
such notice. If Borrower shall fail to give the Administrative  Agent the notice
as specified above for Continuation of a Eurodollar  Advance prior to the end of
the  Interest  Period  applicable  thereto,  such  Eurodollar  Advance  shall be
automatically Continued for a one (1) month Interest Period.

         (b) Conversions.  Borrower shall have the right to Convert an Alternate
Base  Rate  Advance  at  any  time  to  a  Eurodollar   Advance  by  giving  the
Administrative  Agent written notice  specifying:  (i) the Conversion Date; (ii)
the  amount of the  Advance  to be  Converted;  and (iii)  the  duration  of the
Interest Period applicable  thereto,  which notice shall be irrevocable and must
be given by Borrower not later than 11:00 a.m. Dallas, Texas time at least three
(3) Business Days before each such Conversion.  The  Administrative  Agent shall
promptly notify each Lender of the contents of each such notice.

     (c) Default.  After the occurrence and during the continuance of a Default,
no  outstanding  Advances may be Converted  into,  or Continued as, a Eurodollar
Advance.



<PAGE>


         Section  2.7 Use of  Proceeds.  The  proceeds  of  Advances  under  the
Commitments  shall  be  used  by  Borrower  (i)  for  working  capital,  capital
expenditures,  and other lawful corporate  purposes,  (ii) to finance  Permitted
Acquisitions,   Permitted  Other  Business   Acquisitions,   Permitted   Passive
Investments,  and  Permitted  Refractive  Acquisitions,   (iii)  to  the  extent
permitted  by  this  Agreement,  to  repurchase  outstanding  capital  stock  of
Borrower,  (iv) to make loans or capital contributions to its Subsidiaries,  the
proceeds  of  which  are  used by each  such  Subsidiary  for one or more of the
purposes  permitted by subsections (i), (ii), and (iii) of this Section 2.7, and
(v) to finance advances by PMOI or another Guarantor to LASIK Investors,  L.L.C.
for the  acquisition  of  certain  interests  in  certain  Permitted  Refractive
Acquisitions.

         Section 2.8       Fees.

         (a)   Commitment   Fees.   Borrower   hereby   agrees  to  pay  to  the
Administrative   Agent,  for  the  ratable  account  of  each  Lender  having  a
Commitment, a commitment fee on the daily average unused amount of such Lender's
Commitment  for the period from and including the date of this  Agreement to but
excluding the  Termination  Date, at the per annum rate equal to the  Applicable
Unused  Fee  Percentage  based on a 360-day  year,  as the case may be,  and the
actual  number of days  elapsed.  Accrued  commitment  fees  shall be payable in
arrears on each Payment Date and on the Termination Date.

     (b) Agents' Fees. Borrower hereby agrees to pay to the Agents for their own
respective accounts, the fees agreed to by Borrower and the Agents pursuant to a
side letter agreement with each Agent.


                             ARTICLE III -- PAYMENTS

         Section 3.1 Method of Payment. All payments of principal, interest, and
other  amounts to be paid by Borrower  under this  Agreement  and the other Loan
Documents shall be paid to the Administrative  Agent at the Principal Office for
the  account  of each  Lender's  Applicable  Lending  Office in  Dollars  and in
immediately  available funds, without setoff,  deduction,  or counterclaim,  not
later than 1:00 p.m. Dallas,  Texas time on the date on which such payment shall
become due (each such payment made after such time on such due date to be deemed
to have been made on the next succeeding  Business Day).  Borrower shall, at the
time of making each such payment,  specify to the Administrative  Agent the sums
payable by Borrower  under this  Agreement and the other Loan Documents to which
such  payment  is to be  applied  (and in the event  that  Borrower  fails to so
specify,  or if an  Event  of  Default  has  occurred  and  is  continuing,  the
Administrative Agent may apply such payment to the Obligations in such order and
manner as it may elect in its sole  discretion,  subject to Section  3.4).  Each
payment received by the  Administrative  Agent under this Agreement or any other
Loan Document for the account of a Lender shall be paid promptly to such Lender,
in  immediately  available  funds,  for the account of such Lender's  Applicable
Lending  Office.  Whenever  any payment  under this  Agreement or any other Loan
Document  shall be stated to be due on a day that is not a  Business  Day,  such
payment may be made on the next  succeeding  Business Day, and such extension of
time  shall in such  case be  included  in the  computation  of the  payment  of
interest and commitment fee, as the case may be.


<PAGE>


         Section 3.2 Optional Prepayment.  Borrower may, upon at least three (3)
Business  Days' prior notice to the  Administrative  Agent,  prepay the Notes in
whole or in part at any time or from time to time without premium or penalty but
with  accrued  interest  to the date of  prepayment  on the  amount so  prepaid,
provided that (a) Eurodollar  Advances  prepaid on a day other than the last day
of  the  Interest   Period  for  such  Advances  shall  include  the  additional
compensation,  if any, required by Section 4.5, and (b) each partial  prepayment
shall be in the amount of the aggregate remaining  outstanding  principal amount
of the  Eurodollar  Advances or in the principal  amount of  $1,000,000.00  or a
greater integral multiple  thereof.  All notices under this Section 3.2 shall be
irrevocable  and must be given by  Borrower  not later than  11:00 a.m.  Dallas,
Texas  time on the day  which  is not less  than the  number  of  Business  Days
specified above for such notice.  Optional  prepayments  shall be applied as set
forth in Section  3.9.  Optional  prepayments  shall not reduce the  Commitments
unless Borrower so elects pursuant to Section 2.1(b).

         Section 3.3       Mandatory Prepayments.

                  (a) Asset Sales.  Immediately upon the receipt of the proceeds
         thereof,  Borrower shall prepay the Notes in an amount equal to the net
         proceeds of any sale,  liquidation  or disposition of any assets of any
         Company   (other   than  the   Partnerships   or  the   assets  of  the
         Partnerships), where such net proceeds exceed $100,000.00.

               (b) Sale or Issuance of Capital Stock or Debt.  Immediately  upon
          the receipt of the proceeds  thereof,  Borrower shall prepay the Notes
          in an amount equal to 100 percent (100%) of any Issuance Proceeds.

                  (c) Application of Mandatory  Prepayments.  Any such mandatory
         prepayments  of the Notes  shall be  applied to the Notes on a pro rata
         basis based upon the outstanding principal balances of such Notes as of
         the  date of  payment.  Any  such  prepayments  shall  not  reduce  the
         Commitments.

         Section 3.4 Pro Rata Treatment. Except to the extent otherwise provided
herein:  (a) the making and  Continuation of Advances under the Commitment shall
be made pro rata among the Lenders  according to the amounts of their respective
Commitments;  (b) each termination or reduction of the Commitments under Section
2.1(b) or otherwise shall be applied to the Commitments of the Lenders pro rata,
according  to their  respective  unused  Commitments;  and (c) each  payment and
prepayment of principal of or interest on Advances by Borrower  shall be made to
the Administrative Agent for the account of the applicable Lenders in accordance
with Section 3.9.

         Section 3.5 Non-Receipt of Funds by the  Administrative  Agent.  Unless
the  Administrative  Agent shall have been notified by a Lender or Borrower (the
"Payor")  prior to the date on  which  such  Lender  is to make  payment  to the
Administrative Agent of the proceeds of an Advance to be made by it hereunder or
Borrower is to make a payment to the Administrative Agent for the account of one
or more of the Lenders, as the case may be (such payment being herein called the
"Required  Payment"),  which notice shall be effective  upon  receipt,  that the
Payor does not intend to make the Required Payment to the Administrative  Agent,
the Administrative  Agent may assume that the Required Payment has been made and
may, in reliance upon such  assumption  (but shall not be required to), make the
amount  thereof  available  to the  intended  recipient on such date and, if the
Payor has not in fact made the Required Payment to the Administrative Agent, the
recipient of such payment shall, on demand,  return to the Administrative  Agent
the amount made available to it together with interest thereon in respect of the
period  commencing  on the  date  such  amount  was  so  made  available  by the
Administrative  Agent  until the date the  Administrative  Agent  recovers  such
amount at a rate per annum equal to the Federal Funds Rate for such period.


<PAGE>


         Section 3.6 Withholding Taxes. All payments by Borrower of principal of
and interest on the Advances and of all fees and other amounts payable under any
Loan Document are payable without  deduction for or on account of any present or
future taxes,  duties or other charges levied or imposed by the United States of
America or by the  government of any  jurisdiction  outside the United States of
America or by any political  subdivision or taxing authority of or in any of the
foregoing through withholding or deduction with respect to any such payments. If
any such taxes, duties or other charges are so levied or imposed,  Borrower will
pay additional interest or will make additional payments in such amounts so that
every net payment of  principal of and interest on the Advances and of all other
amounts  payable by any of them under any Loan  Document,  after  withholding or
deduction for or on account of any such present or future taxes, duties or other
charges,  will not be less than the  amount  provided  for  herein  or  therein,
provided that Borrower shall have no obligation to pay such  additional  amounts
to any Lender to the extent that such taxes, duties, or other charges are levied
or imposed by reason of the failure of such Lender to comply with the provisions
of Section 3.7. Borrower shall furnish promptly to the Administrative  Agent for
distribution  to each affected  Lender,  as the case may be,  official  receipts
evidencing any such withholding or reduction.

         Section  3.7  Withholding  Tax  Exemption.  Each  Lender  that  is  not
incorporated  under the laws of the United  States of America or a state thereof
agrees that it will  deliver to Borrower  and the  Administrative  Agent two (2)
duly completed  copies of United States  Internal  Revenue  Service Form 1001 or
4224, certifying in either case that such Lender is entitled to receive payments
from Borrower under any Loan Document,  without  deduction or withholding of any
United States federal  income taxes or (b) if such Lender is claiming  exemption
from United States  withholding  tax under Section  871(h) or 881(c) of the Code
with respect to payments of  "portfolio  interest," a Form W-8, or any successor
form prescribed by the Internal Revenue Service, and a certificate  representing
that such Lender is not a bank for  purposes of Section  881(c) of the Code,  is
not a 10-percent  shareholder (within the meaning of Section 871(h)(3)(B) of the
Code) of the Borrower and is not a controlled foreign corporation related to the
Borrower  (within the  meaning of Section  864(d)(4)  of the Code).  Each Lender
which so  delivers a W-8,  Form 1001 or 4224  further  undertakes  to deliver to
Borrower and the Administrative Agent two (2) additional copies of such form (or
a successor form) on or before the date such form expires or becomes obsolete or
after the occurrence of any event  requiring a change in the most recent form so
delivered by it, and such amendments  thereto or extensions or renewals  thereof
as may be reasonably requested by Borrower or the Administrative  Agent, in each
case certifying  that such Lender is entitled to receive  payments from Borrower
under any Loan Document  without  deduction or  withholding of any United States
federal income taxes,  unless an event (including  without limitation any change
in treaty,  law or regulation)  has occurred prior to the date on which any such
delivery would  otherwise be required which renders all such forms  inapplicable
or which would prevent such Lender from duly  completing and delivering any such
form with respect to it and such Lender advises Borrower and the  Administrative
Agent that it is not capable of receiving such payments without any deduction or
withholding of United States federal income tax.

         Section 3.8  Computation of Interest.  Interest on all Advances and all
other amounts payable by Borrower  hereunder shall be computed on the basis of a
year of 360 days, and actual days elapsed.

         Section 3.9       Order of Application.

         (a) No  Default.  Prior to the  occurrence  of an Event of Default  any
payment  (whether  voluntary or  mandatory) of the Notes shall be applied to the
Notes on a pro rata basis based upon the outstanding  principal  balances of the
Notes as of the date of payment.


<PAGE>


         (b) After Default.  After the occurrence and during the  continuance of
an Event of Default,  any payment or proceeds of Collateral  shall be applied in
the  following  order:  (i) to all fees and expenses for which Agents or Lenders
have not been paid or reimbursed in accordance  with the Loan  Documents (and if
such payment is less than all unpaid or unreimbursed fees and expenses, then the
payment shall be paid against unpaid and  unreimbursed  fees and expenses in the
order of incurrence or due date); (ii) to accrued interest on the Notes on a pro
rata basis, based upon the outstanding principal balances of the Notes as of the
date of payment;  (iii) to the  principal of the Notes and amounts due and owing
under  any  Financial  Hedge on a pro rata  basis,  based  upon the  outstanding
principal  balances of the Notes or obligation due and owing under any Financial
Hedge as of the date of payment; and (iv) to all other Obligations.

         (c) Application to Advances.  Subject to the foregoing,  and so long as
no Event of Default has occurred and is continuing, payments of principal of any
Note shall be applied  to such  outstanding  Alternate  Base Rate  Advances  and
Eurodollar Advances under such Note as Borrower shall select; provided, however,
that Borrower shall select Alternate Base Rate Advances and Eurodollar  Advances
to be repaid in a manner  designated to minimize the funding loss required to be
paid pursuant to Section 4.5, if any, resulting from such payment;  and provided
further that if Borrower  shall fail to select the Alternate  Base Rate Advances
and Eurodollar Advances to which such payments are to be applied, or if an Event
of Default has occurred and is continuing at the time of such payment,  then the
Administrative  Agent shall be entitled to apply the payment to such Advances in
the manner in which it shall deem appropriate in its sole discretion.

                  ARTICLE IV -- YIELD PROTECTION AND ILLEGALITY

         Section 4.1       Additional Costs.

         (a) Borrower  hereby agrees to pay directly to each Lender from time to
time such amounts as such Lender may  determine to be necessary to compensate it
for  any  costs  incurred  by such  Lender  which  such  Lender  determines  are
attributable to its making or maintaining any Eurodollar  Advances  hereunder or
its obligation to make any of such Advances  hereunder,  or any reduction in any
amount  receivable  by such Lender  hereunder in respect of any such Advances or
such obligation  (such  increases in costs and reductions in amounts  receivable
being herein called  "Additional  Costs"),  resulting from any Regulatory Change
which:

                  (i) changes  the basis of  taxation of any amounts  payable to
         such Lender under this Agreement or its Notes in respect of any of such
         Advances  (other  than (1) taxes  imposed on the  overall net income of
         such Lender or its Applicable  Lending Office for any of such Advances,
         (2) franchise or similar taxes of such Lender, and (3) amounts withheld
         pursuant to the last sentence of Section 3.7);

                  (ii) imposes or modifies any reserve, special deposit, minimum
         capital,   capital  ratio,  or  similar  requirement  relating  to  any
         extensions  of credit or other assets of, or any deposits with or other
         liabilities or commitments of, such Lender; or

                  (iii)  imposes  any  other   Additional  Cost  affecting  this
         Agreement  or the  Notes  or any  of  such  extensions,  of  credit  or
         liabilities or commitments.


<PAGE>


Each Lender will notify  Borrower of any event  occurring after the date of this
Agreement  which will  entitle  such  Lender to  compensation  pursuant  to this
Section 4.1(a) as promptly as practicable after it obtains knowledge thereof and
determines  to  request  such  compensation,  and  will  designate  a  different
Applicable  Lending  Office  for the  Advances  affected  by such  event if such
designation will avoid the need for, or reduce the amount of, such  compensation
and will not, in the sole  opinion of such  Lender,  violate any law,  rule,  or
regulation or be in any way  disadvantageous to such Lender,  provided that such
Lender shall have no  obligation to so designate an  Applicable  Lending  Office
located outside the United States of America.  Each Lender will furnish Borrower
with a  certificate  setting  forth the basis and the amount of each  request of
such Lender for compensation  under this Section 4.1(a).  If any Lender requests
compensation from Borrower under this Section 4.1(a), Borrower may, by notice to
such Lender (with a copy to the Administrative  Agent) suspend the obligation of
such Lender to make or Continue making Eurodollar  Advances until the Regulatory
Change  giving rise to such  request  ceases to be in effect (in which case such
Lender's  Eurodollar Advances shall be Converted to Alternate Base Rate Advances
in accordance with the provisions of Section 4.4).

         (b) Without  limiting the effect of the  foregoing  provisions  of this
Section 4.1, in the event that, by reason of any Regulatory  Change,  any Lender
either (i) incurs  Additional  Costs based on or measured by the excess  above a
specified level of the amount of a category of deposits or other  liabilities of
such Lender which  includes  deposits by reference to which the interest rate on
Eurodollar Advances is determined as provided in this Agreement or a category of
extensions  of credit or other assets of such Lender which  includes  Eurodollar
Advances  or (ii)  becomes  subject  to  restrictions  on the  amount  of such a
category of  liabilities  or assets which it may hold,  then,  if such Lender so
elects by notice to  Borrower  (with a copy to the  Administrative  Agent),  the
obligation  of such  Lender  to  make or  Continue  making  Eurodollar  Advances
hereunder shall be suspended until such Regulatory Change ceases to be in effect
(in which case such Lender's Eurodollar Advances shall be Converted to Alternate
Base Rate Advances in accordance with the provisions of Section 4.4).

         (c)  Determinations  and allocations by any Lender for purposes of this
Section 4.1 of the effect of any  Regulatory  Change on its costs of maintaining
its  obligations  to make  Advances or of making or  maintaining  Advances or on
amounts  receivable by it in respect of Advances,  and of the additional amounts
required to compensate such Lender in respect of any Additional Costs,  shall be
conclusive,  absent  manifest  error and provided that such  determinations  and
allocations are made on a reasonable basis.

     Section 4.2  Limitation  on  Eurodollar  Advances.  Anything  herein to the
contrary  notwithstanding,  if with  respect to any  Eurodollar  Advance for any
Interest Period therefor:

         (a) The Administrative  Agent determines (which  determination shall be
conclusive  absent  manifest  error) that  quotations of interest  rates for the
relevant  deposits referred to in the definition of "Eurodollar Rate" in Section
1.1  are  not  being  provided  in the  relative  amounts  or for  the  relative
maturities for purposes of determining the rate of interest for such Advances as
provided in this Agreement; or

         (b) The  Required  Lenders  determine  (which  determination  shall  be
conclusive absent manifest error) and notify the  Administrative  Agent that the
rate of interest  referred to in the definition of "Eurodollar  Rate" in Section
1.1 on the  basis  of which  the rate of  interest  for such  Advances  for such
Interest  Period is to be determined do not  accurately  reflect the cost to the
Lenders of making or maintaining such Advances for such Interest Period;

then  the  Administrative  Agent  shall  give  Borrower  prompt  notice  thereof
specifying  the  relevant  amounts  or  periods,  and so long as such  condition
remains in effect,  the Lenders shall be under no obligation to make or Continue
additional  Eurodollar  Advances and Borrower  shall,  on the last day(s) of the
then-current Interest Period(s) for the outstanding Eurodollar Advances,  prepay
such  Eurodollar  Advances or Convert  them to Alternate  Base Rate  Advances in
accordance with Section 4.4.


<PAGE>


         Section 4.3  Illegality.  Notwithstanding  any other  provision of this
Agreement,  in the  event  that  it  becomes  unlawful  for  any  Lender  or its
Applicable  Lending  Office  to (a)  honor  its  obligation  to make  Eurodollar
Advances hereunder,  or (b) maintain  Eurodollar  Advances hereunder,  then such
Lender shall promptly notify Borrower (with a copy to the Administrative  Agent)
thereof and such  Lender's  obligation to make or maintain  Eurodollar  Advances
shall be  suspended  until such time as such Lender may again make and  maintain
Eurodollar  Advances (in which case such Lender's  Eurodollar  Advances shall be
Converted to Alternate  Base Rate Advances in accordance  with the provisions of
Section 4.4).

         Section  4.4  Treatment  of  Eurodollar  Advances.  If  the  Eurodollar
Advances of any Lender are to be Converted  pursuant to Section 4.1, 4.2 or 4.3,
such  Lender's  Eurodollar  Advances  shall  be  automatically   Converted  into
Alternate  Base Rate  Advances on the last day(s) of the then  current  Interest
Period(s) for the Eurodollar  Advances (or, in the case of a Conversion required
by Section 4.1(b) or 4.3(b),  on such earlier date as such Lender may specify to
Borrower  with a copy to the  Administrative  Agent) and,  unless and until such
Lender  gives  notice as  provided  below that the  circumstances  specified  in
Section 4.1, 4.2 or 4.3 which gave rise to such Conversion no longer exist:

         (a) To the extent that such Lender's  Eurodollar  Advances have been so
Converted,  all payments and  prepayments of principal  which would otherwise be
applied to such Lender's  Eurodollar  Advances  shall be applied  instead to its
Alternate Base Rate Advances; and

         (b) All  Advances  which would  otherwise  be made or Continued by such
Lender as Eurodollar  Advances shall be made as or Converted into Alternate Base
Rate Advances.

If such  Lender  gives  notice to  Borrower  (with a copy to the  Administrative
Agent) that the circumstances specified in Section 4.1, 4.2 or Section 4.3 which
gave rise to the  Conversion of such Lender's  Eurodollar  Advances  pursuant to
this Section 4.4 no longer exist (which such Lender  agrees to do promptly  upon
such  circumstances  ceasing to exist) at a time when Advances are  outstanding,
such Lender's Alternate Base Rate Advances shall be automatically  Converted, on
the first day(s) of the next succeeding  Interest Period(s) for such outstanding
Eurodollar  Advances  to the  extent  necessary  so that,  after  giving  effect
thereto,  all Eurodollar  Advances held by the Lenders holding the same are held
pro rata (as to principal amounts and Interest Periods) in accordance with their
respective Commitments.

         Section  4.5  Compensation.  Borrower  shall pay to the  Administrative
Agent,  for the account of each Lender,  upon the request of such Lender through
the Administrative  Agent, such amount or amounts as shall be sufficient (in the
reasonable  opinion of such  Lender) to  compensate  it for any loss,  cost,  or
expense incurred by it as a result of:

         (a) Any payment,  prepayment or Conversion of a Eurodollar  Advance for
any reason (including,  without limitation,  the acceleration of the outstanding
Advances  pursuant  to  Section  11.2) on a date  other  than the last day of an
Interest Period for such Advance; or

         (b)  Any  failure  by  Borrower  for  any  reason  (including,  without
limitation,  the failure of any conditions  precedent specified in Article VI to
be  satisfied)  to borrow or prepay a  Eurodollar  Advance  on the date for such
borrowing  or  prepayment,  specified  in the  relevant  notice of  borrowing or
prepayment under this Agreement.

Such  compensation  shall not exceed the  excess,  if any,  of (i) the amount of
interest which otherwise  would have accrued on the principal  amount so paid or
not  borrowed  for the period from the date of such payment or failure to borrow
to the last day of the  Interest  Period for such  Advance (or, in the case of a
failure  to  borrow,  the  Interest  Period for such  Advance  which  would have
commenced on the date specified for such  borrowing) at the  applicable  rate of
interest for such Advance  provided for herein over (ii) the interest  component
of the amount  such  Lender  would have bid in the London  interbank  market for
Dollar deposits of leading banks and amounts comparable to such principal amount
and with maturities comparable to such period.


<PAGE>


         Section  4.6 Capital  Adequacy.  If after the date  hereof,  any Lender
shall have determined that the adoption or implementation of any applicable law,
rule, or regulation regarding capital adequacy  (including,  without limitation,
any law,  rule,  or regulation  implementing  the Basle  Accord),  or any change
therein,  or any change in the  interpretation or administration  thereof by any
central bank or other Governmental  Authority charged with the interpretation or
administration  thereof,  or  compliance by such Lender (or its parent) with any
guideline,  request,  or directive  regarding  capital adequacy  (whether or not
having the force of law) of any  central  bank or other  Governmental  Authority
(including,  without limitation, any guideline or other requirement implementing
the Basle  Accord),  has or would have the effect of reducing the rate of return
on such Lender's (or its parent's)  capital as a consequence of its  obligations
hereunder or the  transactions  contemplated  hereby to a level below that which
such  Lender  (or  its  parent)  could  have  achieved  but for  such  adoption,
implementation,  change or compliance  (taking into  consideration such Lender's
policies with respect to capital adequacy) by an amount deemed by such Lender to
be material,  then from time to time, within ten (10) Business Days after demand
by such Lender (with a copy to the Administrative  Agent), which demand shall be
delivered  by such Lender to Borrower  as  promptly  as  practicable  after such
Lender obtains knowledge of such reduction in its rate of return, Borrower shall
pay to such Lender such  additional  amount or amounts as will  compensate  such
Lender (or its parent) for such reduction. A certificate of such Lender claiming
compensation  under this  Section and  setting  forth the  additional  amount or
amounts to be paid to it hereunder  shall be conclusive,  absent  manifest error
and provided that the  determination  thereof is made on a reasonable  basis. In
determining such amount or amounts, such Lender may use any reasonable averaging
and attribution methods.

                              ARTICLE V -- SECURITY

         Section 5.1  Collateral.  To secure the full and  complete  payment and
performance of the  Obligations,  Borrower shall execute and deliver or cause to
be executed and delivered the documents  described  below  covering the property
and collateral  described  therein (which,  together with any other property and
collateral  which  may now or  hereafter  secure  the  Obligations  or any  part
thereof, is sometimes herein called the "Collateral"):

     (a) Borrower Security Agreement.  Borrower shall execute and deliver to the
Administrative Agent, for the benefit of the Lenders, the Consent,  Confirmation
and Ratification of the Borrower Security Agreement.

         (b) Guarantor Security Agreement. The existing Guarantors shall execute
and deliver to the  Administrative  Agent,  for the benefit of the Lenders,  the
Consent, Confirmation and Ratification of the Guarantor Security Agreements, and
Prime RVC shall execute and deliver to the Administrative Agent, for the benefit
of the Lenders, a Guarantor Security Agreement.

     (c)  Pledge   Agreement.   Pledgors   shall  execute  and  deliver  to  the
Administrative Agent, for the benefit of the Lenders, the Consent,  Confirmation
and Ratification of the Pledge Agreements.

         (d) Further Assurances. Borrower shall execute and cause to be executed
such further documents and instruments,  including without  limitation,  Uniform
Commercial  Code  financing  statements,  as the  Administrative  Agent  and the
Documentation  Agent, in their sole  discretion,  deem necessary or desirable to
evidence and perfect the Administrative  Agent's liens and security interests in
the Collateral.


<PAGE>


     (e) Description of Collateral. Collateral includes, without limitation, the
following assets of Borrower and Guarantors:

                  (i) All present and future accounts,  contract rights, general
         intangibles,  chattel paper,  documents,  instruments,  notes and other
         debt instruments,  and any collateral therefor,  inventory,  equipment,
         and other goods, wherever located, now owned or hereafter acquired.

                  (ii) All present and future issued and  outstanding  shares of
         capital stock of, or partnership and membership interests, now owned or
         hereafter  acquired by Borrower or any  Guarantor,  including,  without
         limitation,  all  capital  stock  of,  or  partnership  and  membership
         interests in, the Guarantors.

                  (iii) To the  extent  allowed  by the  respective  partnership
         agreements,  certain  partnership  interests  or economic  interests in
         partnership interests owned by Borrower and Guarantors.

                  (iv)  All  present  and  future  automobiles,   trucks,  truck
         tractors, trailers,  semi-trailers,  or other motor vehicles or rolling
         stock now owned or  hereafter  acquired by  Borrower  or any  Guarantor
         (collectively, the "Vehicles").

                  (v) All present and future  rights,  awards,  and judgments to
         which  Borrower or any Guarantor is entitled  under any  litigation now
         existing or hereafter arising.

                  (vi) All present and future rights,  titles,  and interests of
         Borrower or any Guarantor in and to all patents,  patent  applications,
         patent right,  service marks,  trademarks,  tradenames,  trade secrets,
         intellectual property, registrations, goodwill, copyrights, franchises,
         licenses,  permits,  proprietary information,  customer lists, designs,
         and inventions.

                  (vii) All  present and future  books,  records,  data,  plans,
         manuals,  computer  software  and  computer  programs of  Borrower  and
         Guarantors.

               (viii) All  proceeds and  products of the  Collateral  heretofore
          described.

         Section 5.2 Future Liens.  Promptly, and in any event within twenty-one
(21) days after (a) the acquisition of any assets (real, personal,  tangible, or
intangible)  by Borrower or any  Guarantor or (b) the removal,  termination,  or
expiration  of any  prohibition  upon the granting of a lien in any asset (real,
personal,  tangible, or intangible) of any Borrower or any Guarantor (including,
without limitation, the granting of liens in all general and limited partnership
interests  in  which  Borrower  and  Guarantors  own  100%  of  the  partnership
interests) (the "Additional Assets"),  Borrower shall (or shall cause such other
Guarantor  to)  execute  and  deliver  to   Administrative   Agent  all  further
instruments  and documents  (including,  without  limitation,  certificates  and
instruments  representing  shares  of stock or  evidencing  Debt and any  realty
appraisals  as  Administrative  Agent  may  require  with  respect  to any  such
Additional Assets), and shall take all such further action that may be necessary
or desirable,  or that  Administrative  Agent may reasonably  request, to grant,
perfect,  and protect liens in favor of Administrative  Agent for the benefit of
Lenders in such Additional  Assets,  as security for the  Obligations;  it being
expressly  understood  that the  granting of such  additional  security  for the
Obligations  is a material  inducement  to the  execution  and  delivery of this
Agreement by each Lender.  Upon satisfying the terms and conditions hereof, such
Additional  Assets shall be included in the  "Collateral" for all purposes under
the Loan Documents, and all references to the "Collateral" in the Loan Documents
shall include the Additional Assets.


<PAGE>


         Section  5.3  Release  of  Collateral.  Upon  any  sale,  transfer,  or
disposition  of  Collateral  which is expressly  permitted  pursuant to the Loan
Documents  (or is otherwise  authorized by Required  Lenders or Lenders,  as the
case may be), and upon ten (10) Business Days' prior written request by Borrower
(which  request  must be  accompanied  by true  and  correct  copies  of (a) all
documents of transfer or  disposition,  including  any  contract of sale,  (b) a
preliminary closing statement and instructions to the title company, if any, and
(c) all requested release instruments, Administrative Agent shall (and is hereby
irrevocably  authorized  by the  Lenders to) execute  such  documents  as may be
necessary to evidence the release of liens granted to  Administrative  Agent for
the benefit of lenders pursuant hereto in such Collateral; provided that, (x) no
such  release of Lien shall be  granted if any  Default or Event of Default  has
occurred and is continuing,  including,  without limitation, the failure to make
certain  mandatory  prepayments in accordance with Section 3.3(a) in conjunction
with the sale and transfer of such Collateral;  (y)  Administrative  Agent shall
not be required to execute any such document on terms which,  in  Administrative
Agent's opinion,  would expose  Administrative  Agent to liability or create any
obligation  or entail  any  consequence,  other  than the  release of such Liens
without  recourse  or  warranty;  and (z) such  release  shall not in any manner
discharge,  affect,  or impair the Obligations,  or liens upon or obligations of
Borrower or any Guarantor in respect of all  interests  retained by the Borrower
and Guarantors,  including, without limitation, the proceeds of any sale, all of
which shall continue to constitute Collateral.

         Section 5.4 Setoff.  If an Event of Default  shall have occurred and is
continuing,  each Lender is hereby authorized at any time and from time to time,
without  notice to Borrower  (any such notice being hereby  expressly  waived by
Borrower),  to set off and apply any and all deposits (general or special,  time
or demand,  provisional or final) at any time held and other indebtedness at any
time  owing by such  Lender to or for the  credit  or the  account  of  Borrower
against any and all of the  obligations  of Borrower now or  hereafter  existing
under  this  Agreement,  such  Lender's  Notes,  or  any  other  Loan  Document,
irrespective  of whether or not the  Administrative  Agent or such Lender  shall
have made any demand under this  Agreement or such Lender's  Notes or such other
Loan Document and although such obligations may be unmatured. Each Lender agrees
promptly to notify Borrower (with a copy to the Administrative  Agent) after any
such setoff and application, provided that the failure to give such notice shall
not affect the validity of such setoff and application.  The rights and remedies
of  each  Lender  hereunder  are  in  addition  to  other  rights  and  remedies
(including,  without  limitation,  other rights of setoff) which such Lender may
have.

                       ARTICLE VI -- CONDITIONS PRECEDENT

         Section 6.1 Initial Advance.  The obligation of each Lender to make its
initial  Advance is subject to the condition  precedent that the  Administrative
Agent  shall  have  received  on or before  the day of such  Advance  all of the
following,  each dated (unless otherwise indicated) the date hereof, in form and
substance satisfactory to the Administrative Agent:

         (a) Resolutions. Resolutions of the Boards of Directors of Borrower and
each Guarantor  certified by the Secretary or an Assistant  Secretary of each of
them which authorize the execution, delivery, and performance by such Company of
this Agreement and/or the other Loan Documents to which such Company is or is to
be a party;


<PAGE>


         (b) Incumbency  Certificate.  A certificate of incumbency  certified by
the  Secretary  or  an  Assistant  Secretary  of  Borrower  and  each  Guarantor
certifying  the names of the officers of each such  Company,  authorized to sign
this  Agreement and each of the other Loan  Documents to which each such Company
is or is to be a party (including the certificates contemplated herein) together
with specimen signatures of such officers;

     (c) Articles of  Incorporation.  The articles of  incorporation of Borrower
and Guarantors certified by the applicable Secretary of State;

     (d) Bylaws.  The bylaws of Borrower and Litho certified by the Secretary or
an Assistant Secretary of each such Company;

     (e) Governmental  Certificates.  Certificates of the appropriate government
officials  of the  state  of  incorporation  of  Borrower  and  Litho  as to the
existence and good standing of each of them;

         (f)      Notes.  The Notes executed by Borrower;

     (g) Borrower Security  Agreement.  The Borrower Security Agreement executed
by Borrower;

     (h)      Guaranties.  The Guaranty Agreement executed by each Guarantor;

     (i)  Guarantor  Security  Agreements.  The  Guarantor  Security  Agreements
executed by the Guarantors;

     (j) Pledge Agreements.  The Pledge and Security  Agreements executed by the
Pledgors;

     (k) Financing  Statements.  Uniform Commercial Code financing statements or
amendments  executed by Borrower and each Guarantor and covering the Collateral,
as requested by Administrative Agent;

     (l) Stock  Certificates.  Stock  certificates  evidencing all stock pledged
pursuant  to  the  Borrower  Security  Agreement  and  each  Guarantor  Security
Agreement, as applicable, together with stock powers duly executed in blank;

     (m) Certificates of Title.  Original  certificates of title,  together with
executed  applications  for title,  for all vehicles used in connection with the
transportation  of  lithotripters  pledged  pursuant  to the  Borrower  Security
Agreement and the Guarantor Security Agreements;

     (n)  Insurance  Policies.  Copies of all  insurance  policies  required  by
Section  8.5,   together   with  loss  payee   endorsements   in  favor  of  the
Administrative  Agent,  for the  benefit  of the  Lenders,  with  respect to all
insurance policies covering Collateral;

         (o) UCC and Tax and  Judgment  Lien  Searches.  The  results of Uniform
Commercial Code searches showing all financing statements and other documents or
instruments,  and tax and judgment  lien  searches  showing all tax and judgment
liens,  on  file  against  Borrower  and  Litho  in  such  jurisdictions  as the
Administrative  Agent shall  require,  such  searches to be as of a date no more
than twenty (20) days prior to the date of the initial Advance;

     (p) Perfection Certificate. A Perfection Certificate,  in substantially the
form of Exhibit D hereto,  properly  completed and signed by the Chief Executive
or  Chief  Financial  Officer  or Vice  President-Finance  of  Borrower  and the
Guarantors;



<PAGE>


     (q) Opinion of Counsel.  Favorable  opinions as to the matters set forth in
Exhibit E hereto of Akin,  Gump,  Strauss,  Hauer & Feld,  L.L.P.,  Texas  legal
counsel to Borrower and the Guarantors;

     (r)  Attorneys'  Fees and  Expenses.  Evidence  that the costs and expenses
(including attorneys' fees) referred to in Section 13.1, to the extent incurred,
shall have been paid in full by Borrower;

     (s)  Fees.  Borrower  shall  have  paid to the  Agents,  Lenders,  and Lead
Arranger  the fees owed by Borrower to the Agents,  Lenders,  and Lead  Arranger
pursuant to the letter agreements between Borrower and Administrative Agent;

     (t) Federal Reserve Board Form U-1. For the Administrative Agent a properly
completed  Federal Reserve Board Form U-1 duly executed by each Company pledging
stock of another Company; and

         (u) No Material  Adverse Change.  No material adverse change shall have
occurred  since  September  30,  1999  in  the  business,   assets,  operations,
conditions  (financial  or  otherwise)  or prospects of the  Companies or in the
facts  and  information  delivered  to  Lenders  on or  prior to the date of the
initial Advance.

     Section 6.2 All Advances. The obligation of each Lender to make any Advance
(including  the  initial  Advance)  is  subject  to  the  following   additional
conditions precedent:

     (a) Advance Request Form. The Administrative Agent shall have received,  in
accordance  with Section 2.5, an Advance  Request Form executed by an authorized
officer of Borrower;

     (b) No Default. No Default shall have occurred and be continuing,  or would
result from such Advance;

         (c)  Representations  and Warranties.  All of the  representations  and
warranties  contained  in  Article  VII  hereof  and in each of the  other  Loan
Documents  shall be true and correct on and as of the date of such  Advance with
the same force and effect as if such  representations  and  warranties  had been
made on and as of such date, except to the extent that such  representations and
warranties  speak to a specific date or the facts on which such  representations
and warranties are based have been changed by  transactions  contemplated by the
Loan Documents;

     (d) Availability.  After giving effect to requested Advances, the remaining
availability  under  the  Commitment  shall be no less  than  the then  existing
Consolidated Earn-Out  Indebtedness,  as evidenced by the calculations set forth
in the Advance Request Form; and

         (e) Permitted Refractive  Acquisitions.  In connection with any Advance
the proceeds of which will be used to finance a Permitted Refractive Acquisition
by Prime Refractive,  L.L.C.,  Administrative Agent shall receive the following,
each in form and substance acceptable to Administrative Agent:

               (i) A subordinated  promissory note  substantially in the form of
          Exhibit L hereto made by Prime Refractive  Management,  L.L.C. payable
          to the  order  of  Borrower,  PMOI or  Prime  RVC,  together  with the
          guaranty thereof by Prime Refractive, L.L.C., and the pledge of assets
          (including any interests in Subsidiaries  and  Partnerships)  of Prime
          Refractive  Management,  L.L.C. and Prime Refractive,  L.L.C., and the
          interest of LASIK Investors,  L.L.C. in Prime Refractive,  L.L.C., all
          duly perfected and assigned to Administrative Agent;



<PAGE>


                  (ii) A subordination  agreement  substantially  in the form of
         Exhibit M hereto, between the payee of the subordinated note, the maker
         of the subordinated note,  Administrative Agent, and the administrative
         agent under the Advancing Term Facility; and

                  (iii)  Such  endorsements,   financing  statements,  corporate
         authorizations   and   other   documents    reasonably   requested   by
         Administrative Agent.

     (f) Additional Documentation.  The Administrative Agent shall have received
such additional  approvals,  opinions, or documents as are required by the terms
and provisions of this Agreement or any other Loan Document.


                  ARTICLE VII -- REPRESENTATIONS AND WARRANTIES

         To induce  the Agents  and the  Lenders  to enter into this  Agreement,
Borrower hereby represents and warrants to the Agents and the Lenders that:

         Section 7.1       Existence.

         (a) Corporate Existence. Each of the Companies (other than the Excepted
Subsidiaries and the Partnerships): (a) is a corporation duly organized, validly
existing,  and in  good  standing  under  the  laws of the  jurisdiction  of its
incorporation;  (b) has all requisite  corporate  power and authority to own its
assets and carry on its  business as now being or as  proposed to be  conducted;
and (c) is qualified to do business in all  jurisdictions in which the nature of
its business makes such qualification  necessary and where failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Borrower,  or any Material  Subsidiary.  Each  Company  (other than the Excepted
Subsidiaries)  has the corporate  power and authority to execute,  deliver,  and
perform its  obligations  under this  Agreement and the other Loan  Documents to
which it is or may become a party.

         (b) Partnership Existence.  Each of the Partnerships:  (a) is a general
partnership,  limited  partnership or limited liability company, as appropriate,
duly  organized,  validly  existing,  and in good standing under the laws of the
jurisdiction  of its  formation;  (b) has all  requisite  partnership  power and
authority or company power and authority, as appropriate,  to own its assets and
carry on its  business as now being or as proposed to be  conducted;  and (c) is
qualified  to do  business  in all  jurisdictions  in which  the  nature  of its
business  makes such  qualification  necessary  and where  failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Borrower, or any Material Subsidiary.

         Section  7.2  Financial  Statements.  Borrower  has  delivered  to  the
Administrative Agent audited consolidated  financial statements of the Companies
as  of  and  for  the  fiscal  year  ended  December  31,  1998,  and  unaudited
consolidated  financial  statements  of Borrower  for the nine (9) month  period
ended  September  30, 1999.  Such  financial  statements  have been  prepared in
accordance with GAAP, and fairly present, on a consolidated basis, the financial
condition of the Companies and Litho and the Partnerships, as appropriate, as of
the  respective  dates  indicated  therein and the results of operations for the
respective periods indicated therein.  There has been no material adverse change
in the business,  condition (financial or otherwise),  operations, or properties
of the Companies taken as a whole,  Borrower,  or any Material  Subsidiary since
the effective date of the most recent financial  statements  referred to in this
Section.


<PAGE>


         Section 7.3 Corporate Action: No Breach. The execution,  delivery,  and
performance  by each Company of this  Agreement and the other Loan  Documents to
which such  Company is or may become a party and  compliance  with the terms and
provisions  hereof  and  thereof  have been  duly  authorized  by all  requisite
corporate action (or, if such Company is a partnership, then partnership action)
on the part of such  Company  and do not and will not (a)  violate  or  conflict
with, or result in a breach of, or require any consent under (i) the articles of
incorporation  or bylaws of such Company (or, if such Company is a  partnership,
then the partnership  agreement of such Company),  (ii) any material  applicable
law, rule, or regulation or any material order, writ,  injunction,  or decree of
any  Governmental  Authority or arbitrator,  or (iii) any material  agreement or
instrument  to which such  Company is a party or by which such Company or any of
its property is bound or subject (other than agreements and instruments relating
to Debt which will be paid off with the proceeds of the initial Advance), or (b)
constitute a material default under any such agreement or instrument (other than
agreements  and  instruments  relating  to Debt  which will be paid off with the
proceeds of the initial Advance), or result in the creation or imposition of any
Lien (except as provided in Article V) upon any of the revenues or assets of any
of the Companies.

         Section 7.4 Operation of Business.  Each of the  Companies  (other than
the Excepted Subsidiaries) possesses all licenses, permits, franchises, patents,
copyrights,  trademarks, and tradenames, or rights thereto, necessary to conduct
their  respective  businesses  substantially  as now  conducted and as presently
proposed to be  conducted.  None of the  Companies  is in violation of any valid
rights of others with respect to any of the foregoing  (except where the failure
to do so would not have a material  adverse  effect on the  business,  condition
(financial or otherwise),  operations or properties of the Companies  taken as a
whole, Borrower, or any Material Subsidiary).

         Section 7.5 Litigation and Judgments.  As of the date hereof, except as
disclosed on Schedule 7.5 hereto,  there is no action, suit,  investigation,  or
proceeding before or by any Governmental  Authority or arbitrator pending, or to
the knowledge of Borrower, threatened against or affecting any of the Companies,
that would,  if  adversely  determined,  have a material  adverse  effect on the
business,  condition  (financial or otherwise),  operations or properties of the
Companies taken as a whole,  Borrower, or any Material Subsidiary or the ability
of  Borrower  to pay and  perform  the  Obligations.  There  are no  outstanding
judgments against any Company.

         Section 7.6 Rights in Properties; Liens. Each of the Companies has good
and  indefeasible  title to or valid  leasehold  interests  in their  respective
material  properties and assets,  real and personal,  including the  properties,
assets, and leasehold interests reflected in the financial  statements described
in Section 7.2, and none of the properties,  assets,  or leasehold  interests of
any Company is subject to any Lien, except as permitted by Section 9.2.

         Section 7.7 Enforceability.  This Agreement constitutes,  and the other
Loan Documents to which Borrower is a party,  when delivered,  shall  constitute
the legal,  valid,  and binding  obligations  of Borrower,  enforceable  against
Borrower  in  accordance  with  their  respective  terms,  except as  limited by
bankruptcy,  insolvency,  or other laws of general  application  relating to the
enforcement of creditors'  rights. The Loan Documents to which each Guarantor is
a party,  when  delivered,  shall  constitute  the  legal,  valid,  and  binding
obligations of such Guarantor,  enforceable against such Guarantor in accordance
with their respective  terms,  except as limited by bankruptcy,  insolvency,  or
other laws of general  application  relating to the  enforcement  of  creditors'
rights.


<PAGE>


         Section 7.8 Approvals.  No authorization,  approval, or consent of, and
no filing or registration with, any Governmental  Authority or third party is or
will be necessary for the execution, delivery, or performance by Borrower or any
Guarantor of this  Agreement and the other Loan  Documents to which  Borrower or
any  Guarantor  is or may become a party or for the  validity or  enforceability
thereof.

     Section 7.9 Debt. As of the date hereof, the Companies have no Debt, except
as disclosed on Schedule 7.9.

         Section   7.10  Taxes.   The   Companies   (other  than  the   Excepted
Subsidiaries) have filed or extended all tax returns (federal, state, and local)
required to be filed, including all income, franchise, employment, property, and
sales tax returns, and have paid all of their respective  liabilities for taxes,
assessments,  governmental  charges,  and other  levies that are due and payable
other than certain state tax returns  required to be filed on or before the date
hereof.  Except as previously  disclosed to the Administrative Agent in writing,
no  Company  knows of any  pending  investigation  of any of them by any  taxing
authority or of any pending but unassessed tax liability of any of them,  except
relating to the Excepted Subsidiaries.

         Section 7.11 Use of Proceeds;  Margin Securities. No Company is engaged
principally, or as one of its important activities, in the business of extending
credit for the  purpose of  purchasing  or  carrying  margin  stock  (within the
meaning  of  Regulations  T, U, or X of the Board of  Governors  of the  Federal
Reserve  System),  and no part of the  proceeds of any  Advance  will be used to
purchase or carry any margin stock or to extend credit to others for the purpose
of  purchasing  or carrying  margin  stock,  except for  purchases of Borrower's
capital stock permitted by Section 9.4 hereof.

         Section 7.12 ERISA.  The  Companies  are in  compliance in all material
respects with all applicable provisions of ERISA. Neither a Reportable Event nor
a Prohibited  Transaction  has occurred  and is  continuing  with respect to any
Plan.  No notice of intent to terminate a Plan has been filed,  nor has any Plan
been terminated.  No circumstances  exist which constitute grounds entitling the
PBGC to institute proceedings to terminate,  or appoint a trustee to administer,
a Plan, nor has the PBGC instituted any such proceedings.  None of the Companies
nor  any  ERISA   Affiliate  has  completely  or  partially   withdrawn  from  a
Multi-employer  Plan.  The  Companies  and each ERISA  Affiliate  have met their
minimum funding requirements under ERISA with respect to all of their Plans, and
the  present  value of all vested  benefits  under each Plan does not exceed the
fair market value of all Plan assets  allocable to such benefits,  as determined
on the most recent  valuation,  date of the Plan and in  accordance  with ERISA.
None of the Companies nor any ERISA  Affiliate has incurred any liability to the
PBGC under ERISA.

         Section 7.13  Disclosure.  All factual  information  (taken as a whole)
furnished  by or on behalf of  Borrower  in  writing  to any Agent or any Lender
(including,  without limitation,  all factual information  contained in the Loan
Documents) for purposes of or in connection with this Agreement,  the other Loan
Documents or any  transaction  contemplated  herein or therein is, and all other
such factual  information (taken as a whole) hereafter furnished by or on behalf
of Borrower in writing will be, true and  accurate in all  material  respects on
the date as of which such factual  information  is dated or certified and is not
(and such factual  information  (taken as a whole) hereafter  furnished will not
be)  incomplete  by omitting to state any facts  necessary  to make such factual
information  (taken as a whole) not  misleading in any material  respect at such
time in light of the  circumstances  under which such  factual  information  was
provided.


<PAGE>


         Section 7.14  Subsidiaries;  Partnerships.  Each of the Guarantors is a
direct or  indirect  wholly-owned  Subsidiary  of  Borrower,  and as of the date
hereof,  together with the Partnerships  listed on Schedule 3, constitute all of
the Subsidiaries of Borrower.  Schedule 7.14.1,  as the same may be amended from
time to time to reflect transactions permitted by this Agreement, sets forth the
outstanding shares of capital stock (or other ownership  interests) and the name
of  each  shareholder  of  each  of the  Subsidiaries  of  Borrower.  All of the
outstanding  capital  stock of Borrower  and each of its  Subsidiaries  has been
validly issued,  is fully paid, and is  nonassessable.  Schedule 7.14.2,  as the
same may be amended from time to time to reflect transactions  permitted by this
Agreement,  sets forth the outstanding partnership interests of the Partnerships
owned by each of the Companies.

         Section 7.15 Agreements.  Except for the Senior Subordinated Indenture,
the Senior  Subordinated  Notes,  and as set forth on Schedule 7.15, none of the
Companies is a party to any  indenture,  loan,  or credit  agreement,  or to any
lease or other  agreement or instrument,  or subject to any charter or corporate
restriction which could reasonably be expected to have a material adverse effect
on the business, condition (financial or otherwise), operations or properties of
the  Companies  taken as a whole,  Borrower,  or any Material  Subsidiary or the
ability of Borrower or any  Guarantor to pay and perform its  obligations  under
the Loan  Documents to which it is a party.  None of the Companies is in default
in any material respect in the performance, observance, or fulfillment of any of
the  obligations,  covenants,  or  conditions  contained  in  any  agreement  or
instrument to which it is a party, which default, in the aggregate with all such
other defaults, would have a material adverse affect on the business,  condition
(financial or otherwise),  operations or properties of the Companies  taken as a
whole, Borrower, or any Material Subsidiary.

     Section   7.16   Compliance   with   Legal    Requirements;    Governmental
Authorizations.

         (a) Except for the Excepted  Subsidiaries  and as set forth in Schedule
7.16.1:  (i) each Company is in  compliance  in all material  respects with each
Legal Requirement that is or was applicable to it or to the conduct or operation
of its  business  or the  ownership  or use of any of its  assets;  and  (ii) no
Company has received  any notice or other  communication  from any  Governmental
Authority or other Person of any event or circumstance  which could constitute a
violation of, or failure to comply with, any Legal Requirement.

         (b) Except for the Excepted  Subsidiaries  and as set forth in Schedule
7.16:  (i) each  Company  is in  material  compliance  with all of the terms and
requirements of each Governmental  Authorization  held by such Company;  (ii) no
Company has received  any notice or other  communication  from any  Governmental
Authority or other Person of, any event or circumstance which could constitute a
violation  of,  or  failure  to  comply  with,  any term or  requirement  of any
Governmental   Authorization,   or  of  any  actual  or  potential   revocation,
withdrawal,  cancellation  or termination of, or material  modification  to, any
Governmental  Authorization;  (iii) all applications required to have been filed
for the renewal of any required Governmental Authorizations have been duly filed
on a timely basis with the appropriate Governmental  Authorities,  and all other
filings   required  to  have  been  made  with  respect  to  such   Governmental
Authorizations  have  been  duly  made on a timely  basis  with the  appropriate
Governmental Authorities;  (iv) all Governmental Authorizations of the Companies
are  transferable to the Companies;  (v) upon  consummation of the  transactions
contemplated  hereby,  the Companies  will  lawfully hold all such  Governmental
Authorizations; and (vi) none of such Governmental Authorizations will terminate
upon  consummation  of the  transactions  contemplated  hereby.  Except  for the
Excepted  Subsidiaries  and as set forth on Schedule 7.16, each of the Companies
possesses the necessary Governmental Authorizations (i) necessary to permit each
Company to lawfully conduct and operate its respective business in the manner it
currently  conducts and operates such business and to permit such Company to own
and use its  assets  in the  manner  in which it  currently  owns and uses  such
assets, and (ii) necessary to permit each Company,  upon the consummation of the
transactions  contemplated  hereby, to lawfully conduct and operate its business
and to permit each Company to own and use its assets,  where the failure to have
such  Governmental  Authorization  would have a material  adverse  effect on the
business,  condition  (financial or otherwise),  operations or properties of the
Companies taken as a whole, Borrower, or any Material Subsidiary.


<PAGE>


     Section 7.17 Investment Company Act. No Company is an "investment  company"
within the meaning of the Investment Company Act of 1940, as amended.

         Section  7.18  Public  Utility  Holding  Company  Act.  No Company is a
"holding  company"  or a  "subsidiary  company"  of a  "holding  company"  or an
"affiliate" of a "holding  company" or a "public  utility" within the meaning of
the Public Utility Holding Company Act of 1935, as amended.

     Section 7.19 Environmental  Matters.  Except as disclosed on Schedule 7.19,
as the same may be amended from time to time, hereto:

         (a)  Each of the  Companies  and all of  their  respective  properties,
assets,  and  operations  are in  compliance  in all material  respects with all
Environmental Laws. No Company is aware of, nor have any of them received notice
of, any past, present, or future conditions,  events, activities,  practices, or
incidents  which may  interfere  with or  prevent  the  material  compliance  or
continued  material  compliance  of any Company with all material  Environmental
Laws; and

         (b) The  Companies  have  obtained all material  permits,  licenses and
authorizations  that are required under applicable  Environmental  Laws, and all
such  permits are in good  standing  and each  Company is in  compliance  is all
material respects with all of the terms and conditions of such permits.

         Section 7.20 Year 2000 Compliance. Borrower represents that it is aware
of the possible impact of the year 2000 problem (that is, the risk that computer
applications may not be able to properly perform date-sensitive  functions after
December  31,  1999)  upon its  computer  applications  and  on-going  business.
Borrower  represents that any corrective action necessary will be taken and that
the year 2000  problem  will not  result  in a  material  adverse  change in the
Companies' business condition (financial or otherwise),  operations,  properties
or prospects, or ability to repay the Obligations.

                       ARTICLE VIII -- POSITIVE COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe each of the following positive covenants:

     Section  8.1   Reporting   Requirements.   Borrower  will  furnish  to  the
Administrative Agent and each Lender:

         (a) Annual Financial Statements. As soon as available, and in any event
within  ninety-five  (95) days after the end of each  fiscal  year of  Borrower,
beginning  with the fiscal year ending  December  31, 1998, a copy of the annual
audit report of the Companies for such fiscal year containing, on a consolidated
basis, balance sheets and statements of income, retained earnings, and cash flow
as at the end of such  fiscal  year and for the twelve  (12)-month  period  then
ended,  in each case  setting  forth in  comparative  form the  figures  for the
preceding fiscal year,  audited by independent  certified public  accountants of
recognized standing, and accompanied by an opinion of such independent certified
public accountants stating that such report has been prepared in accordance with
GAAP;


<PAGE>


         (b) Monthly  Financial  Statements.  As soon as  available,  and in any
event  within forty (40) days after the end of each month of each fiscal year of
Borrower, a copy of an unaudited financial report of the Companies as of the end
of such month and for the portion of the fiscal year then ended, containing,  on
a  consolidated  basis,  balance  sheets and  statements  of income and retained
earnings,  in each case setting  forth in  comparative  form the figures for the
corresponding  period  of the  preceding  fiscal  year,  certified  by the chief
financial  officer of Borrower to have been prepared in accordance with GAAP and
to fairly and accurately  present  (subject to year-end audit  adjustments)  the
financial   condition  and  results  of  operations  of  the  Companies,   on  a
consolidated basis, at the date and for the periods indicated therein;

         (c) Quarterly Financial  Statements.  As soon as available,  and in any
event within  forty-five  (45) days after the end of each quarter of each fiscal
year of Borrower, a copy of an unaudited financial report of the Companies as of
the end of such  quarter  and for the  portion  of the fiscal  year then  ended,
containing,  on a consolidated  basis,  balance sheets and statements of income,
retained earnings, and cash flow, in each case setting forth in comparative form
the figures for the corresponding period of the preceding fiscal year, certified
by the chief  financial  officer of Borrower to have been prepared in accordance
with GAAP and to fairly  and  accurately  present  (subject  to  year-end  audit
adjustments) the financial condition and results of operations of the Companies,
on a consolidated basis, at the date and for the periods indicated therein,  and
a copy of an unaudited  financial report of Prime RVC and its Subsidiaries as of
the end of such quarter  beginning with the fiscal quarter ending March 31, 2000
and for the portion of the fiscal year then ended, containing, on a consolidated
and  consolidating  basis,  balance  sheets and  statements of income,  retained
earnings,  and cash flow,  in each case setting  forth in  comparative  form the
figures for the corresponding  period of the preceding fiscal year, certified by
the chief  financial  officer or treasurer of Borrower to have been  prepared in
accordance with GAAP and to fairly and accurately  present  (subject to year-end
audit  adjustments)  the financial  condition and results of operations of Prime
RVC and its Subsidiaries, on a consolidated and consolidating basis, at the date
and for the periods indicated therein;

         (d) Compliance  Certificate.  Concurrently with the delivery of each of
the financial  statements  referred to in Section  8.1(a) and within  forty-five
(45) days after the end of each of the first  three (3) fiscal  quarters of each
fiscal year of Borrower,  a certificate of the chief executive,  chief financial
officer or treasurer of Borrower,  in  substantially  the form of Exhibit F, (i)
stating  that to such  officer's  knowledge,  no  Default  has  occurred  and is
continuing,  or if a Default has occurred and is  continuing,  a statement as to
the nature  thereof and the action  that is  proposed  to be taken with  respect
thereto,  and (ii) showing in reasonable  detail the calculations  demonstrating
compliance with Article X;

     (e) Accounts Receivable Aging Report. As soon as available and in any event
within  forty  (40) days  after the end of each  month,  an aged  listing of the
accounts  receivable of each of Borrower and its  Subsidiaries  as of the end of
such month in a form reasonably satisfactory to the Administrative Agent;

     (f)  Business  Plan and Budget.  As soon as  available  and in any event by
January  15 of each  year,  a copy of the annual  budget  and  business  plan of
Borrower and its Subsidiaries for such fiscal year, together with details of the
assumptions, if any, underlying such budget and business plan;

     (g)  Management  Letters.  Promptly  upon  receipt  thereof,  a copy of any
management  letter or written  report  submitted  to any Company by  independent
certified public accountants with respect to the business,  condition (financial
or otherwise), operations, or properties of any Company;



<PAGE>


         (h) Notice of  Litigation.  Promptly  after the  commencement  thereof,
notice of all actions,  suits, and proceedings before any Governmental Authority
or arbitrator affecting Borrower or any of its Subsidiaries which, if determined
adversely  to Borrower  or any such  Subsidiary,  could have a material  adverse
effect  on  the  business,  condition  (financial  or  otherwise),  options,  or
properties of Borrower, any Subsidiary or the Companies (taken as a whole);

         (i) Notice of Default. As soon as possible and in any event within five
(5) days after  Borrower  knows of the  occurrence  of each  Default,  a written
notice  setting  forth the details of such Default and the action that  Borrower
has taken and proposes to take with respect thereto;

         (j) ERISA Reports. Promptly after the filing or receipt thereof, copies
of all reports,  including  annual reports,  and notices which any Company files
with or receives from the PBGC or the U.S.  Department of Labor under ERISA; and
as soon as  possible  and in any event  within  five (5) days after any  Company
knows or has reason to know that any Reportable Event or Prohibited  Transaction
has  occurred  with  respect to any Plan or that the PBGC,  or any  Company  has
instituted or will  institute  proceedings  under Title IV of ERISA to terminate
any Plan, a certificate of the chief financial officer of Borrower setting forth
the  details  as to such  Reportable  Event or  Prohibited  Transaction  or Plan
termination and the action that Borrower proposes to take with respect thereto;

         (k) Reports to Other Creditors.  Promptly after the furnishing thereof,
copies  of  any  statement  or  report  furnished  by  Borrower  or  any  of its
Subsidiaries to any other creditor to which any Company owes $250,000.00 or more
or to the trustee under the Senior Subordinated Indenture, pursuant to the terms
of any  indenture,  loan,  or  credit or  similar  agreement  and not  otherwise
required to be furnished to the Administrative Agent and the Lenders pursuant to
any other clause of this Section;

         (l) Proxy Statements,  Etc. As soon as available,  one (1) copy of each
financial statement,  report,  notice or proxy statement sent by Borrower to its
stockholders  generally  and one (1) copy of each  regular,  periodic or special
report,  registration  statement,  or  prospectus  filed  by  Borrower  with any
securities  exchange or the Securities and Exchange  Commission or any successor
agency including, without limitation, all Forms 10-K, 10-Q and 8-K and all other
periodic reports required to be filed under the Securities  Exchange Act of 1934
and the rules and regulations promulgated thereunder;

         (m)  Partnership  Lists.  As soon as  available,  and in any  event (a)
within thirty (30) days after the Administrative Agent requests such information
from  Borrower,  a list of the names and  addresses of each partner or member of
each of the  Partnerships  and  percentage  ownership  by each  Company  of each
Partnership;

         (n) Governmental Authorizations. Upon the request of the Administrative
Agent, but not more often than one (1) time during each fiscal year of Borrower,
a complete and accurate list of each Governmental  Authorization held by each of
Companies or that  otherwise  relate to the business of, or to any of the assets
owned or used by, each of the Companies;

         (o) Dilution  Reports.  Promptly upon the  occurrence of any Restricted
Transfer (as hereinafter  defined), a report setting forth the occurrence of any
Restricted Transfer, including the name of the Partnership, purchasers, purchase
price,   and  EBITDA  for  the   immediately   preceding  four  fiscal  quarters
attributable  thereto, and also of the contribution of any Partnership assets to
any  other  Partnership,   including  the  names  of  the  Partnerships,  assets
transferred, value thereof and consideration received;


<PAGE>


         (p) Partnership Actions.  Promptly after the incurrence thereof, notice
of any Partnership's (i) incurrence of Debt, (ii) change in accounting treatment
or reporting practices (which change shall not affect any reporting requirements
set  forth  herein  or the Loan  Documents),  except  as  permitted  by GAAP and
disclosed to the Administrative  Agent, (iii) change in tax reporting treatment,
except  as  permitted  by law,  (iv)  amendment  of any  partnership  agreement,
regulations,  or management  agreement  between such Partnership and any Company
and copies of any such  amendment  certified  by an officer of Borrower as being
true and correct, and (v) change in its insurance; and

     (q)  General  Information.  Promptly,  such  other  information  concerning
Borrower or any of its  Subsidiaries as the  Administrative  Agent or any Lender
may from time to time reasonably request.

         Section 8.2  Maintenance  of Existence;  Conduct of Business.  Borrower
will  preserve  and  maintain  its  corporate  existence  and all of its leases,
privileges, licenses, permits, franchises,  qualifications,  and rights that are
necessary or desirable in the ordinary  conduct of its  business.  Borrower will
cause each of its Subsidiaries other than the Excepted Subsidiaries, to preserve
and maintain its corporate,  partnership  or other similar  existence and all of
its leases, privileges, licenses, permits, franchises, qualifications and rights
that are necessary or desirable in the ordinary conduct of its business, except,
in each case, where failure to do so would not have a material adverse effect on
the business,  condition  (financial or otherwise),  operations or properties of
the Companies taken as a whole,  Borrower, or any Material Subsidiary.  Borrower
will conduct,  and will cause each of its Subsidiaries to conduct,  its business
in an orderly and efficient manner in accordance with good business practices.

         Section 8.3  Maintenance of Properties.  Borrower will maintain,  keep,
and  preserve,  and  cause  each of its  Subsidiaries  to  maintain,  keep,  and
preserve, all of its properties (tangible and intangible) necessary or useful in
the proper conduct of its business in good working order and condition,  except,
in each case,  as  permitted by Section 9.8 or 9.9 or where the failure to do so
would not have a material adverse effect on the business,  condition  (financial
or  otherwise),  operations or  properties  of the  Companies  taken as a whole,
Borrower, or any Material Subsidiary.

         Section 8.4 Taxes and Claims. Borrower will pay or discharge,  and will
cause each of its Subsidiaries other than the Excepted  Subsidiaries,  to pay or
discharge,  at or before maturity or before becoming delinquent (a) all material
taxes, levies, assessments, and governmental charges imposed on it or its income
or profits or any of its material  property,  and (b) all material lawful claims
for labor,  material,  and supplies,  which, if unpaid, might become a Lien upon
any of its property; provided, however, that no Company shall be required to pay
or discharge any tax, levy,  assessment,  or governmental  charge which is being
contested in good faith by appropriate  proceedings  diligently pursued, and for
which adequate reserves have been established.


<PAGE>


         Section 8.5 Insurance.  Borrower will maintain,  and will cause each of
its Subsidiaries to maintain (except in the case of the  Partnerships,  in which
case Borrower shall maintain for the  Partnerships),  insurance with financially
sound and reputable  insurance companies in such amounts and covering such risks
as is usually carried by corporations  engaged in similar  businesses and owning
similar  properties in the same general  areas in which the  Companies  operate,
consistent  with past practices of the Companies and to the extent  available on
commercially reasonable terms, provided that in any event Borrower will maintain
and cause each of its Subsidiaries  (except in the case of the Partnerships,  in
which case Borrower shall maintain for the  Partnerships) to maintain  workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance, professional liability insurance, and business interruption insurance
reasonably   satisfactory  to  the  Lenders.   Each  insurance  policy  covering
Collateral shall name the Administrative Agent as loss payee, for the benefit of
the Lenders, as its interests may appear and shall provide that such policy will
not be canceled or reduced without thirty (30) days' prior written notice to the
Administrative  Agent.  Borrower will annually provide the Administrative  Agent
with all  certificates  of  insurance  evidencing  all  policies of insurance of
Borrower and its Subsidiaries.

         Section 8.6 Inspection  Rights. At any reasonable time and from time to
time after reasonable notice to Borrower,  Borrower will permit,  and will cause
each of its Subsidiaries to permit,  representatives of the Administrative Agent
and each Lender to examine,  copy, and make extracts from its books and records,
to visit and inspect its  properties,  and to discuss its business,  operations,
and financial  condition with its officers,  and  independent  certified  public
accountants.  Prior to removing  any such  copies or  extracts  from a Company's
premises,  such  Company's   representatives  shall  be  provided  a  reasonable
opportunity to review such information and mark or identify it as "confidential"
or "confidential information" as reasonably deemed appropriate by such Company.

         Section 8.7 Keeping Books and Records. Borrower will maintain, and will
cause each of its  Subsidiaries to maintain,  proper books of record and account
in which full,  true, and correct  entries in conformity with GAAP shall be made
of all dealings and transactions in relation to its business and activities.

         Section 8.8 Compliance with Laws.  Borrower will comply, and will cause
each of its Subsidiaries to comply,  in all material  respects with all material
applicable laws,  rules,  regulations,  orders,  and decrees of any Governmental
Authority or arbitrator.

         Section 8.9 Compliance with Agreements.  Borrower will comply, and will
cause each of its  Subsidiaries  to comply,  in all material  respects  with all
agreements, contracts, and instruments binding on it or affecting its properties
or business, except where the failure to do so would not have a material adverse
effect on the  business,  condition  (financial  or  otherwise),  operations  or
properties  of the  Companies  taken  as a  whole,  Borrower,  or  any  Material
Subsidiary.

         Section 8.10 Further Assurances. Borrower will (a), and will cause each
of its Subsidiaries  (other than the  Partnerships) to, execute and deliver such
further  agreements  and  instruments  and take  such  further  action as may be
reasonably requested by the Administrative Agent to carry out the provisions and
purposes of this  Agreement and the other Loan Documents and, (b) and will cause
each of its Subsidiaries (including the Partnerships) to, create,  preserve, and
perfect the Liens of the  Administrative  Agent, for the benefit of the Lenders,
in the Collateral.

         Section 8.11 ERISA.  Borrower  will comply,  and will cause each of its
Subsidiaries  to comply,  with all minimum funding  requirements,  and all other
material  requirements,  of ERISA, if applicable,  so as not to give rise to any
liability thereunder.

         Section 8.12 Information  Relating to Proposed  Acquisitions.  Borrower
will use its best  efforts  to keep the  Administrative  Agent  and the  Lenders
informed  of the  relevant  information  and  status of and will  share with the
Administrative  Agent and the Lenders and provide copies to the extent possible,
of all material due diligence  information  relating to any proposed Acquisition
with respect to which Borrower or any Subsidiary  enters into a letter of intent
or acquisition agreement, during the term of this Agreement.


<PAGE>


         Section  8.13  After-Acquired   Subsidiaries.   Concurrently  upon  the
formation  or  Acquisition  by Borrower  or any  Guarantor  of any  Wholly-Owned
Subsidiary  after  the date  hereof  (pursuant  to a  Permitted  Acquisition  or
otherwise)   (an   "After-Acquired   Subsidiary"),   Borrower  shall  cause  the
After-Acquired  Subsidiary to deliver  articles of  incorporation,  bylaws,  and
resolutions (or other corresponding  constituent documents) and such opinions as
the  Administrative  Agent shall  require  and to execute a Guaranty,  Guarantor
Security Agreement,  and Pledge Agreement (if applicable),  as shall be required
by the  Administrative  Agent to  create  first  priority  Liens in favor of the
Administrative  Agent,  for the benefit of the Lenders,  in such  After-Acquired
Subsidiary's assets, to secure the Obligations.

         Section 8.14 Syndication  Cooperation.  Borrower  acknowledges that the
Agents intend  promptly to commence to syndicate the  Commitments of the Lenders
in accordance  with the provisions of Section 13.6.  Borrower agrees to actively
assist  Agents  and  their   Affiliates  in  achieving  a  syndication  that  is
satisfactory  to Agents and Borrower and in preparing  information  requested by
Agents in connection  with arranging and  syndication of the  Commitments of the
Lenders  and to take  such  other  action  deemed  necessary  by Agents or their
Affiliates,  including  the  holding  of a formal  presentation  to  prospective
Lenders to achieve a successful  syndication of the  Commitments by Agents.  The
syndication  efforts will be accomplished  by a variety of means,  including the
preparation  of  a  confidential  information  memorandum  and  other  marketing
materials,  direct contact  during the  syndication  between  senior  management
(including, but not limited to, the chief executive officer, the chief financial
officer and treasurer of Borrower)  and advisors and  Affiliates of Borrower and
the proposed syndicate Lenders.

                        ARTICLE IX -- NEGATIVE COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe the following negative covenants:

         Section 9.1A Debt. Borrower will not incur,  create,  assume, or permit
to exist,  nor permit any of its Subsidiaries  (other than the  Partnerships) to
incur, create, assume, or permit to exist, any Debt, except:

          (a) Debt  owed to the  Agents  and the  Lenders  pursuant  to the Loan
     Documents;

          (b)  Existing Debt described on Schedule 7.9 hereto;

     (c)  The  Exchange  Notes  and  guaranties   thereof  by  any  Wholly-Owned
Subsidiary;

          (d) Debt owed to Borrower or to any Wholly-Owned Subsidiary;

         (e) Debt in an aggregate  principal amount not to exceed  $2,000,000.00
at any time  outstanding  the proceeds of which are used by Borrower or Litho to
purchase equipment, other than lithotripters, prostatrons, and lasers;

     (f) Any Company's  obligations as general  partner of a Partnership for the
Debt of such Partnership;

     (g) Any Company's Guarantee of Debt of any Partnership,  if such Company is
a general partner of such Partnership;

     (h) Debt not exceeding $1,750,000 in outstanding  principal amount incurred
by AK Associates,  L.L.C.  in connection with the acquisition and improvement of
real estate;

         (i)      Any Financial Hedge; and


<PAGE>


         (j)      The Advancing Term Facility and Guarantees thereof.

         Section 9.1B Debt of Refractive Entities. The Companies will not incur,
create,  assume,  or permit to exist Debt (other than the  Obligations  and Debt
under the Advancing Term Facility) exceeding $6,500,000 in outstanding principal
amount  incurred  to finance or  refinance  acquisitions  of  equipment  used in
correcting  refractive  error  of the eye,  provided  that of such  Debt,  Prime
Refractive Management,  L.L.C., any of its Subsidiaries,  or any Partnerships in
which  they are a  partner  may only be liable  for  $4,000,000  in  outstanding
principal amount of such Debt.

         Section  9.2  Limitation  on Liens.  Borrower  will not incur,  create,
assume,  or permit to exist, nor permit any of its Subsidiaries  (other than the
Partnerships) to incur, create, assume, or permit to exist, any Lien upon any of
their respective properties, assets, or revenues, whether now owned or hereafter
acquired, except:

         (a)      Liens disclosed on Schedule 9.2;

     (b) Purchase money Liens securing Debt  permitted by Section  9.1A(d),  (e)
and (k);

     (c) Liens in favor of the  Administrative  Agent,  for the  benefit  of the
Lenders or the counter-party under any Financial Hedge;

         (d) Encumbrances consisting of minor easements, zoning restrictions, or
other  restrictions on the use of real property that do not  (individually or in
the aggregate)  materially affect the value of the assets encumbered  thereby or
materially impair the ability of Borrower or any of its Subsidiaries to use such
assets in their  respective  businesses,  and none of which is  violated  in any
material respect by existing or proposed structures or land use;

         (e) Liens for taxes,  assessments,  or other governmental charges which
are not  delinquent  or which are being  contested  in good  faith and for which
adequate reserves have been established;

     (f)  Liens of  mechanics,  materialmen,  warehousemen,  carriers,  or other
similar  statutory  Liens  securing  obligations  that  are  not yet due and are
incurred in the ordinary course of business;

         (g) Liens  resulting  from good faith  deposits  to secure  payments of
workmen's  compensation  or other  social  security  programs  or to secure  the
performance of tenders,  statutory  obligations,  surety and appeal bonds, bids,
contracts  (other  than for  payment of Debt),  or leases  made in the  ordinary
course of business;

     (h)  Lien  on real  property  and  improvements  of AK  Associates,  L.L.C.
securing Debt described in Section 9.1A(h) above;

         (i) Liens  securing the Advancing  Term  Facility;  provided such Liens
granted by Borrower and the  Guarantors are  subordinated  in form and substance
satisfactory  to  the  Administrative  Agent  to  the  Liens  in  favor  of  the
Administrative Agent; and

         (j)  Liens  securing   subordinated  Debt  owing  to  PMOI  or  another
Guarantor,  the proceeds of which were used to finance a portion of the purchase
price of a Permitted Refractive Acquisition.


<PAGE>


     Section 9.3  Mergers,  Etc.  Except upon the prior  written  consent of the
Required  Lenders,  neither  Borrower nor any Guarantor will become a party to a
merger or consolidation,  except: (a) any of R.R. Litho, Inc., Ohio Litho, Inc.,
Prime  Diagnostic  Services,  Inc.,  Prime  Diagnostic  Corp. of Florida,  Prime
Practice Management,  Inc., Prime Cardiac Rehabilitation  Services,  Inc., Prime
Lithotripsy  Services,  Inc.,  Alabama Renal Stone  Institute,  Inc.,  and Prime
Kidney  Stone  Treatment,  Inc.  may merge or  consolidate  into  Prime  Medical
Operating,  Inc., so long as (w) Prime Medical Operating,  Inc. is the surviving
entity,  (x) no Default or Event of Default  exists or would exist as the result
of such merger or consolidation,  (y) no partnership agreement to which any such
Guarantor is a party would be breached by such merger or consolidation,  and (z)
Borrower and the applicable  Guarantors  give  Administrative  Agent at least 15
Business Days prior written notice of any proposed merger or  consolidation  and
execute and deliver any Guaranty Agreement, Guarantor Security Agreement, Pledge
Agreement,    Uniform   Commercial   Code   financing   statements,    corporate
documentation,  and opinions of counsel as required by the Administrative  Agent
to create or continue first priority Liens in favor of the Administrative Agent,
for the benefit of the Lenders,  in the assets of the surviving entity to secure
the Obligations, and (b) in connection with any Permitted Acquisition, Permitted
Other  Business  Acquisition,  or Permitted  Refractive  Acquisition  so long as
Borrower or a Guarantor is the surviving entity. Borrower will not, and will not
permit  any of its  Subsidiaries  (other  than the  Partnerships)  to,  wind-up,
dissolve or  liquidate  itself,  except as permitted  in  subsection  (a) above.
Except as otherwise permitted by this Agreement, Borrower will not, and will not
permit  any of its  Subsidiaries  to,  form,  incorporate,  acquire  or make any
investment in any  Subsidiary,  except (a) the  Subsidiaries  listed on Schedule
7.14.1,  (b)  Subsidiaries  acquired or formed through a Permitted  Acquisition,
Permitted Other Business Acquisition, Permitted Passive Investment, or Permitted
Refractive  Acquisition,  (c)  Subsidiaries  formed or acquired through the BDEC
Acquisition, or the Horizon Acquisition and (d) Wholly-Owned Subsidiaries formed
in accordance with Section 8.13.

         Section 9.4 Restricted  Payments.  Borrower will not declare or pay any
dividends or make any other payment or distribution  (whether in cash, property,
or obligations) on account of its capital stock, or redeem, purchase, retire, or
otherwise acquire any of its capital stock, or permit any of its Subsidiaries to
purchase or otherwise  acquire any capital  stock of Borrower,  or set apart any
money  for a  sinking  or  other  analogous  fund  for  any  dividend  or  other
distribution on its capital stock or for any redemption,  purchase,  retirement,
or other acquisition of any of its capital stock; provided,  however, that, from
the date hereof through and including the Termination Date,  Borrower may redeem
or retire and/or the Companies may purchase shares of Borrower's  capital stock,
whether through issuance and performance of a put agreement,  or otherwise,  for
an aggregate  consideration  of no more than  $11,993,000 on and after September
30, 1999,  provided that upon  completion of such  purchases or  redemptions  no
Default or Event of Default would exist or be continuing,  and provided  further
that the  proceeds  from the sale of any Stock  previously  redeemed by Borrower
shall increase the limit hereunder dollar for dollar to the extent such proceeds
have been applied as set forth in Section  3.3(b).  Borrower shall not permit to
exist any  arrangement,  agreement,  or corporate  governance  agreement,  which
directly or indirectly  prohibits or restricts any Subsidiary  from declaring or
paying  any  dividend  or  distribution,   on  account  of  its  capital  stock,
partnership,  limited liability company, or other ownership interests,  provided
that  provisions in such  agreements  providing for the payment of Debt prior to
the payment of any dividend or distribution shall not violate this Section.

         Section 9.5 Investments.  Borrower will not make, nor permit any of its
Subsidiaries  to make,  any  advance,  loan,  extension  of  credit,  or capital
contribution  to or  investment  in, or  purchase  or own,  or permit any of its
Subsidiaries to purchase or own, any stock, bonds, notes,  debentures,  or other
securities of, any Person, except:


<PAGE>


         (a) The Companies,  or any of them, may purchase (i) readily marketable
direct  obligations  of the United States of America or any agency  thereof with
maturities of one year or less from the date of acquisition,  (ii) fully insured
certificates  of deposit  with  maturities  of one year or less from the date of
acquisition  issued by any  commercial  bank  operating in the United  States of
America  having  capital  and  surplus  in excess of  $1,000,000,000,  and (iii)
commercial  paper of a domestic  issuer if at the time of purchase such paper is
rated in one (1) of the two (2) highest rating categories of Standard and Poor's
Rating  Group,  a division of McGraw  Hill,  Inc.,  a New York  corporation,  or
Moody's Investors Service, Inc.;

         (b)  The  Companies,  or any of  them,  may  make  loans  to  officers,
directors  and  employees  of any of them  provided  such  loans are made in the
ordinary  course of business,  and are in an aggregate  principal  amount of not
more than $200,000.00 at any time outstanding;

     (c)  Borrower may  continue to hold  capital  stock of American  Physicians
Service Group, Inc. held by Borrower on the date hereof;

         (d) The Borrower and Guarantors may create new Subsidiaries, hold stock
in Subsidiaries  and  themselves,  and engage in the  transactions  permitted by
Section 9.3 hereof, provided that Borrower complies with Section 8.13;

         (e)      Existing Permitted Passive Investments;

         (f) Permitted Acquisitions,  Permitted Other Business Acquisitions, and
Permitted Passive Investments;  provided however,  that Permitted  Acquisitions,
Permitted Other Business Acquisitions, and Permitted Passive Investments made by
Companies  other than the Borrower or a Guarantor shall not in the aggregate for
all such Companies exceed the lesser of: (a) $3,000,000.00; and (ii) 3% of Total
Equity;

         (g)      Permitted Refractive Acquisitions;

          (h)  Borrower may make a loan to AK  Associates,  L.L.C.  described in
               Section 9.1A(h) and Section 9.2(h) above;

         (i)      Any Financial Hedge;

         (j)      the BDEC Acquisition, and the Horizon Acquisition;

          (k)  the  $200,000  working  capital line of credit from PMOI or Prime
               RVC to Prime Refractive, L.L.C., in form and substance acceptable
               to Administrative Agent;

          (l)  the formation of and, as  applicable,  contribution  of assets to
               Prime/BDR Acquisition,  L.L.C.,  Prime/BDEC Acquisition,  L.L.C.,
               Prime  Refractive,   L.L.C.,  and  Prime  Refractive  Management,
               L.L.C.;

          (m)  the   aggregate   $11,035,000   loans  from  PMOI  to   Prime/BDR
               Acquisition,  L.L.C.,  the proceeds of which were used to finance
               the Horizon Acquisition;

          (n)  the purchase by PMOI of the  interests in Prime/BDR  Acquisition,
               L.L.C. owned by the other owners of Prime/BDR Acquisition, L.L.C.
               on  the  dates  and  for  the  purchase  price  required  by  the
               Contribution  Agreement (the  "Contribution  Agreement")  entered
               into  among  PMOI,  Borrower,   Prime/BDR  Acquisition,   L.L.C.,
               Prime/BDEC  Acquisition,  L.L.C., Mark Rosenberg,  the sellers of
               the  refractive  surgery eye center  assets,  and  certain  other
               parties; and


<PAGE>


         (o)      loans  by PMOI or any  other  Guarantor  to  LASIK  Investors,
                  L.L.C. required by the Contribution Agreement in effect on the
                  date  hereof,  so long as such  loans are  secured  by a first
                  priority   Lien   in  the   interests   being   acquired   and
                  Administrative  Agent on  behalf  of the  Lenders  receives  a
                  perfected, first priority lien in such loan and the Collateral
                  therefor.

         Section 9.6 Limitation on Issuance of Capital Stock.  Borrower will not
permit any of its Subsidiaries to at any time issue,  sell, assign, or otherwise
dispose of (a) any of its capital stock or other  ownership  interests,  (b) any
securities  exchangeable  for or  convertible  into or  carrying  any  rights to
acquire  any of its  capital  stock or  other  ownership  interests,  or (c) any
option,  warrant,  or other right to acquire  any of its capital  stock or other
ownership  interests;  provided,  however,  that any  Subsidiary of Borrower may
issue, sell, assign or otherwise dispose of its capital stock or other ownership
interests,  or securities  exchangeable for its capital stock or other ownership
interests, to Borrower or any other Wholly-Owned Subsidiary.

         Section 9.7 Transactions With Affiliates. Borrower will not enter into,
and will not permit any of its  Subsidiaries  to enter  into,  any  transaction,
including,  without limitation,  the purchase,  sale, or exchange of property or
the rendering of any service,  with any Affiliate of Borrower or any  Subsidiary
of Borrower,  except in the ordinary  course of Borrower's or such  Subsidiary's
business  and upon fair and  reasonable  terms no less  favorable to Borrower or
such Subsidiary than would be obtained in a comparable arm's-length  transaction
with a Person not an Affiliate of Borrower or such Subsidiary.  No Company shall
make any loan,  advance,  investment,  or  transfer  any assets to any  Excepted
Subsidiary,  so long as such Excepted  Subsidiary is not in good standing  where
incorporated.


<PAGE>


         Section  9.8  Disposition  of Assets.  Borrower  will not sell,  lease,
assign,  transfer,  or otherwise dispose of any of its assets, nor permit any of
its  Subsidiaries  (other  than  the  Partnerships)  to do so with  any of their
respective  assets,  except  (subject to the mandatory  prepayments  required by
Section 3.3) (a)  inter-Company  transfers  between  Borrower and a Wholly-Owned
Subsidiary or between  Wholly-Owned  Subsidiaries,  (b)  dispositions of assets,
other than  lithotripters,  in the ordinary course of business for consideration
of up to an aggregate amount of $1,000,000.00 during the term of this Agreement,
(and the Administrative Agent agrees to execute and deliver releases of Liens in
connection with such  dispositions),  (c)  dispositions by any Company of assets
used in  connection  with cardiac  rehabilitation  or  diagnostic  imaging,  (d)
dispositions of any tangible assets that are worn or obsolete, (e) contributions
of assets to Prime/BDEC Acquisition, L.L.C. as contemplated pursuant to the BDEC
Acquisition;  (f) the  sale by PMOI of its  ownership  interests  in  Prime/BDEC
Acquisition,  L.L.C. (or all of Prime/BDEC Acquisition,  L.L.C.'s assets) on the
dates  and  for the  purchase  price  required  by the  Contribution  Agreement,
provided that such tangible  assets are replaced by assets of similar  character
where  the  replacement  of such  asset  is  necessary  or  appropriate  for the
continued  conduct of such Company's  business as presently  conducted,  and (g)
transfers by Borrower or by any Subsidiary of interests in Partnerships, so long
as the aggregate  EBITDA  Transfer for all Restricted  Transfers does not exceed
the lesser of : (a) ten percent (10%) of Borrower's EBITDA for the most recently
ended four fiscal quarters,  and (b) $6,500,000 and included within such amount,
the aggregate EBITDA Transfer for all Restricted LASIK Transfers does not exceed
the  lesser  of:  (a) ten  percent  (10%) of the  EBITDA of Prime  RVC,  and (b)
$2,000,000.  "EBITDA Transfer" with respect to any Partnership  interests in any
Partnership  transferred  by Borrower or any  Subsidiary  shall equal the EBITDA
generated by such Partnership  interests for the last four fiscal quarters prior
to the date of such  transfer of each such  Partnership  interest.  A Restricted
Transfer  shall be any transfer or series of related  transfers  of  Partnership
interests in any one  Partnership  by Borrower or any  Subsidiary  in any 90 day
period,  in which the EBITDA Transfer equals or exceeds  $250,000.  A Restricted
LASIK  Transfer  shall  be any  transfer  or  series  of  related  transfers  of
Partnership  interests  by Prime  RVC or any of its  Subsidiaries  in which  the
EBITDA  Transfer  equals  or  exceeds  $250,000.  In the  case of any  transfers
pursuant to paragraph (g), after giving effect to such transfers, a Company must
Control such  Partnership.  Administrative  Agent is  authorized  to release any
liens on such Partnership interests transferred pursuant to this Section 9.8, as
further set forth in Section 5.3.

         Section  9.9 Sale and  Leaseback.  Borrower  will not enter  into,  nor
permit any of its Subsidiaries  (other than the Partnerships) to enter into, any
arrangement  with any Person (other than another  Company)  pursuant to which it
leases from such Person  equipment used in lithotripsy  operations that has been
or is to be sold or transferred,  directly or indirectly,  by it to such Person;
provided,  however,  that the Companies may enter into any arrangement  with any
Person  pursuant to which it leases  from such Person real or personal  property
not  used  in  lithotripsy  operations  that  has  been  or  is to  be  sold  or
transferred,  directly or  indirectly,  by it to such  Person,  in an  aggregate
amount of up to but not to exceed $500,000.00 during the term of this Agreement.

         Section 9.10 Prepayment of Debt.  Borrower will not prepay,  nor permit
any of its Subsidiaries to prepay,  any Debt except the  Obligations,  or redeem
the Senior Subordinated Notes other than a redemption of a portion of the Senior
Subordinated  Notes  pursuant  to  Section  3.07  of  the  Senior   Subordinated
Indenture,  so long as after  giving  effect  thereto,  no  Default  or Event of
Default would exist.

         Section 9.11 Nature of Business. Borrower will not, and will not permit
any of its Subsidiaries (other than the Partnerships) to, engage in any business
other  than the  businesses  in which  they are  engaged  on the date  hereof or
businesses  which  are  reasonably  related  thereto;  provided,  however,  that
Borrower  will not and will not permit any of its  Subsidiaries  (other than the
Partnerships)  not already in the business of providing  non-medical  management
services to cardiac  rehabilitation or diagnostic imaging operations,  to engage
in either such business.

         Section 9.12 Environmental Protection.  Borrower will not, and will not
permit any of its  Subsidiaries  to,  conduct  any  activity or use any of their
respective  properties or assets in any manner that could reasonably be expected
to violate any  Environmental  Law or create any  Environmental  Liabilities for
which Borrower or any of its Subsidiaries would be responsible.

         Section 9.13 Accounting.  Borrower will not, and will not permit any of
its  Subsidiaries  (other than the  Partnerships)  to, change its fiscal year or
make any change (a) in accounting  treatment or reporting  practices,  except as
permitted  by GAAP and  disclosed  to the  Administrative  Agent,  or (b) in tax
reporting treatment, except as permitted by law.

         Section  9.14  Amendment  of  Partnership  and  Management  Agreements.
Borrower  will not,  and will not permit any of its  Subsidiaries  to, amend any
partnership agreements,  regulations,  or articles of any of the Partnerships or
any management  agreements  between any Company and any of the Partnerships,  if
such amendment could reasonably be expected to have a material adverse effect on
the business,  condition (financial or otherwise),  operations, or properties of
the Companies taken as a whole, Borrower, or any Material Subsidiary.

         Section 9.15      Financial Hedges.

         (a) To the extent any Lender or its Affiliate  issues a Financial Hedge
to any  Company,  such Lender or its  Affiliate is afforded the benefits of (and
Borrower [or any Company by execution of Collateral Documents] hereby confirms a
grant  of)  Liens  in and to  the  Collateral  as  evidenced  by the  Collateral
Documents  to the  extent  of such  Lender's  (or  Affiliate  thereof's)  credit
exposure  under  such  Financial  Hedge;  such Lien is pari  passu  with that of
Administrative Agent on behalf of the Lenders.


<PAGE>


         (b)  Financial  Hedges  held  by any  Company  permitted  by  the  Loan
Documents,  shall be subject  to the  following:  (i) each such  Lender or other
institution  issuing a Financial  Hedge shall calculate its credit exposure in a
reasonable and customary manner; (ii) all documentation for such Financial Hedge
shall conform to ISDA standards and must be acceptable to  Administrative  Agent
with  respect  to  intercreditor  issues;  (iii) if issued by any  Lender or any
Affiliate  of a Lender to Borrower,  the credit  exposure  under such  Financial
Hedge shall be secured by Liens in and to the  Collateral  as  evidenced  by the
Collateral  Documents  on a pari passu  basis  with the Liens of  Administrative
Agent (held for the benefit of Lenders),  and such Lender or Affiliate issuing a
Financial  Hedge  shall,  by  acceptance  of the  benefits  of such Liens in the
Collateral  agree to the  provisions  of Section 12.6;  and (iv) such  Financial
Hedge shall be incurred in the ordinary  course of business and consistent  with
prior business practices of the Companies and not for speculative purposes.

         Section 9.16 Control of Prime Refractive, L.L.C. Borrower or one of its
Wholly-Owned  Subsidiaries must own at least 51% of the membership  interests in
and Control Prime Refractive, L.L.C.

                        ARTICLE X -- FINANCIAL COVENANTS

         Borrower  hereby  covenants and agrees that, as long as the Obligations
or any part thereof are outstanding or any Lender has any Commitment  hereunder,
Borrower will perform and observe the following financial covenants:

         Section 10.1 Total Net Funded Debt to EBITDA.  Borrower will not permit
the Total Net Funded Debt to EBITDA Ratio, determined as of the last day of each
fiscal  quarter of the Companies and for the four (4) fiscal quarter period then
ending, to exceed the ratio set forth opposite such period below:

================================================= ==============================

                                  Period Ratio

- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

January 1, 1998 through December 31, 2000                    3.50 to 1.0
- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

January 1, 2002 and thereafter                               3.00 to 1.0
================================================= ==============================

         Section 10.2 Senior Net Funded Debt To EBITDA Ratio.  Borrower will not
permit the Senior  Net  Funded  Debt to EBITDA  Ratio as of the last day of each
fiscal  quarter of  Borrower to exceed the ratio set forth  opposite  such dates
below:

================================================= ==============================

                                  Period Ratio

- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

January 1, 1998 through December 31, 2000                     2.50 to 1.0
- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

January 1, 2002 and thereafter                                2.00 to 1.0
================================================= ==============================

         Section 10.3 Debt Service Coverage Ratio.  Borrower will not permit the
Debt  Service  Coverage  Ratio  as of the  last day of each  fiscal  quarter  of
Borrower to be less than the ratio set forth opposite such dates below:


<PAGE>


================================================= ==============================

                                  Period Ratio

- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

January 1, 1998 through December 31, 2000                       1.50 to 1.0
- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

- ------------------------------------------------- ------------------------------
- ------------------------------------------------- ------------------------------

January 1, 2002 and thereafter                                  1.75 to 1.0
================================================= ==============================

         Section 10.4  Consolidated Net Worth.  Borrower shall not permit, as of
the last day of each fiscal quarter of Borrower,  its  Consolidated Net Worth to
be less than $86,005,000,  such amount to be increased beginning with the fiscal
quarter ending December 31, 1999, and on the last day of each successive  fiscal
quarter of Borrower  by an amount  equal to one  hundred  percent  (100%) of the
increase in net worth arising from any  Acquisition  or equity  issuance  during
such fiscal  quarter,  (b) increased on December 31, 1999 and on the last day of
each successive  fiscal quarter of Borrower,  by an amount equal to seventy-five
percent (75%) of positive  Consolidated Net Income for such fiscal quarter;  and
(c)  decreased  on any date after  September  30,  1999 by the amount of capital
stock of Borrower  repurchased  or retired by Borrower  or any  Subsidiary,  not
exceeding $11,993,000 in the aggregate.

                              ARTICLE XI -- DEFAULT

     Section 11.1 Events of Default.  Each of the  following  shall be deemed an
"Event  of  Default":

     (a) Borrower  shall fail to pay when due any amount of principal  under any
Note.

         (b)  Borrower  shall  fail to pay to the  Administrative  Agent  or any
Lender (through the  Administrative  Agent),  any interest on the Advances,  any
fees due  hereunder or under any other Loan  Document,  or any other part of the
Obligations  which  does not  constitute  principal  under the  Notes,  and such
failure  shall  continue for three (3) Business  Days after such payment  became
due.

         (c) Any  representation  or warranty made or deemed made by Borrower or
any Obligated Party (or any of their  respective  officers) in any Loan Document
or in any certificate,  report,  notice, or financial statement furnished at any
time in connection with this Agreement shall be false, misleading,  or erroneous
in any  material  respect  when made or deemed to have been made and the  effect
thereof  shall not have been cured  within ten (10)  Business  Days after notice
thereof to  Borrower  by the  Administrative  Agent or any Lender  (through  the
Administrative Agent).

         (d)  Borrower  shall  fail to  perform,  observe,  or  comply  with any
covenant,  agreement,  or  term  contained  in  Article  X; or  Borrower  or any
Obligated  Party shall fail to perform,  observe,  or comply with any  covenant,
agreement or term  contained in Section 8.1 (a),  (b), (c) or (d), or Article IX
and such failure  shall  continue for a period of three (3) Business  Days after
notice thereof to Borrower by the  Administrative  Agent or any Lender  (through
the  Administrative  Agent);  or Borrower or any  Obligated  Party shall fail to
perform, observe br comply with any other covenant, agreement, or term contained
in this  Agreement or any other Loan Document  (other than  covenants to pay the
Obligations)  and such failure shall  continue for a period of ten (10) Business
Days after notice thereof to Borrower by the Administrative  Agent or any Lender
(through the Administrative Agent).


<PAGE>


         (e)  Any  Company  shall  commence  a  voluntary   proceeding   seeking
liquidation, reorganization, or other relief with respect to itself or its debts
under any  bankruptcy,  insolvency,  or other  similar law now or  hereafter  in
effect or seeking the appointment of a trustee, receiver, liquidator, custodian,
or other similar  official of it or a substantial  part of its property or shall
consent to any such relief or to the appointment of or taking  possession by any
such official in an involuntary case or other proceeding commenced against it or
shall make a general  assignment for the benefit of creditors or shall generally
fail to pay its debts as they become due or shall take any  corporate  action to
authorize any of the foregoing.

         (f) An involuntary  proceeding  shall be commenced  against any Company
seeking liquidation,  reorganization,  or other relief with respect to it or its
debts under any bankruptcy, insolvency, or other similar law now or hereafter in
effect or seeking the appointment of a trustee, receiver, liquidator,  custodian
or other  similar  official for it or a substantial  part of its  property,  and
either such involuntary  proceeding shall remain  undismissed and unstayed for a
period of forty-five (45) days or an order for relief is entered.

         (g) Any Company  shall fail to discharge  within a period of forty-five
(45) days after the  commencement  thereof  any  attachment,  sequestration,  or
similar  proceeding or proceedings,  including  without  limitation any order of
forfeiture,  seizure or divestiture  (whether under RICO or otherwise) involving
an  aggregate  amount in excess of Five  Hundred  Thousand  and  00/100  Dollars
($500,000.00) against any of its assets or properties.

         (h) A final judgment or judgments for the payment of money in excess of
Five Hundred Thousand and 00/100 Dollars ($500,000.00) in the aggregate shall be
rendered  by a court or courts  against  any  Company  and the same shall not be
discharged  (or provision  shall not be made for such  discharge),  or a stay of
execution  thereof shall not be procured,  within  forty-five (45) days from the
date of entry  thereof  and such  Company  shall  not,  within  said  period  of
forty-five  (45) days, or such longer period during which  execution of the same
shall have been stayed,  appeal therefrom and cause the execution  thereof to be
stayed during such appeal.

         (i) Any Company shall fail to pay when due any principal of or interest
on the  Senior  Subordinated  Notes or on any  other  Debt  (including,  without
limitation,  the Advancing  Term Facility) in an aggregate  principal  amount of
Five Hundred  Thousand and 00/100 Dollars  ($500,000.00) or more (other than the
Obligations),  or the maturity of the Senior Subordinated Notes or any such Debt
shall  have been  accelerated,  or the  Senior  Subordinated  Notes  (except  in
connection  with the exchange  thereof for the Exchange  Notes) or any such Debt
shall have been required to be prepaid prior to the stated maturity thereof,  or
any event shall have occurred that permits (or, with the giving of notice or the
lapse of time or both,  would  permit)  any  holder  or  holders  of the  Senior
Subordinated Notes or such Debt or any Person acting on behalf of such holder or
holders to accelerate the maturity thereof or require any such prepayment.

         (j) This Agreement or any other Loan Document shall cease to be in full
force  and  effect  or  shall be  declared  null  and  void or the  validity  or
enforceability  thereof  shall be  contested  or  challenged  by  Borrower,  any
Subsidiary  of  Borrower,  any  Obligated  Party  or  any  of  their  respective
shareholders,  or  Borrower  or any  Obligated  Party shall deny that it has any
further liability or obligation under any of the Loan Documents,  or any Lien or
security interest created by the Loan Documents shall for any reason cease to be
a valid,  first priority perfected security interest in and Lien upon any of the
Collateral purported to be covered thereby.


<PAGE>


         (k) Any of the  following  events  shall occur or exist with respect to
Borrower or any ERISA Affiliate:  (i) any Prohibited  Transaction  involving any
Plan; (ii) any Reportable Event with respect to any Plan; (iii) the filing under
Section  4041 of  ERISA of a  notice  of  intent  to  terminate  any Plan or the
termination of any Plan;  (iv) any event or circumstance  that might  constitute
grounds entitling the PBGC to institute  proceedings under Section 4042 of ERISA
for the termination  of, or for the appointment of a trustee to administer,  any
Plan, or the institution by the PBGC of any such proceedings; or (v) complete or
partial  withdrawal  under  Section 4201 or 4204 of ERISA from a  Multi-employer
Plan or the  reorganization,  insolvency,  or termination of any  Multi-employer
Plan; and in each case above,  such event or condition,  together with all other
events or conditions,  if any, have subjected or could in the reasonable opinion
of the Required Lenders subject  Borrower,  or any of its  Subsidiaries,  to any
tax, penalty, or other liability to a Plan, a Multi-employer  Plan, the PBGC, or
otherwise (or any  combination  thereof) which in the aggregate  exceed or could
reasonably  be expected  to exceed  Five  Hundred  Thousand  and 00/100  Dollars
($500,000.00).

         (l)      Any Change in Control shall occur.

         Section  11.2  Remedies.  If any Event of  Default  shall  occur and be
continuing,  the  Administrative  Agent  may (and if  directed  by the  Required
Lenders, shall) do any one or more of the following:

                  (a)  Acceleration.  Declare all  outstanding  principal of and
         accrued and unpaid  interest on the Notes and all other  obligations of
         Borrower under the Loan Documents  immediately due and payable, and the
         same  shall  thereupon  become  immediately  due and  payable,  without
         notice,   demand,   presentment,   notice   of   dishonor,   notice  of
         acceleration,  notice  of  intent  to  accelerate,  protest,  or  other
         formalities  of any kind, all of which are hereby  expressly  waived by
         Borrower;

               (b) Termination of Commitments. Terminate the Commitments without
          notice to Borrower;

               (c) Judgment. Reduce any claim to judgment;

               (d) Foreclosure.  Foreclose or otherwise enforce any Lien granted
          to the Administrative  Agent for the benefit of itself and the Lenders
          to secure  payment and  performance  of the  Obligations in accordance
          with the terms of the Loan Documents; and

               (e) Rights.  Exercise any and all rights and remedies afforded by
          the laws of the  State of Texas or any other  jurisdiction,  by any of
          the Loan Documents, by equity, or otherwise;

provided,  however,  that  upon the  occurrence  of an Event  of  Default  under
subsection  (e) or (f) of Section 11.1,  the  Commitments  of all of the Lenders
shall automatically  terminate, and the outstanding principal of and accrued and
unpaid  interest on the Notes and all other  obligations  of Borrower  under the
Loan  Documents  shall  thereupon  become  immediately  due and payable  without
notice, demand, presentment, notice of dishonor, notice of acceleration,  notice
of intent to accelerate, protest, or other formalities of any kind, all of which
are hereby expressly waived by Borrower.

         Section 11.3 Performance by the Administrative Agent. If Borrower shall
fail to perform any covenant or agreement  in  accordance  with the terms of the
Loan Documents,  the Administrative  Agent may, at the direction of the Required
Lenders,  perform or attempt to perform such  covenant or agreement on behalf of
Borrower.  In such event,  Borrower shall, at the request of the  Administrative
Agent,  promptly  pay any amount  expended  by the  Administrative  Agent or the
Lenders in connection  with such  performance  or attempted  performance  to the
Administrative Agent at the Principal Office,  together with interest thereon at
the  Default  Rate  from  and  including  the  date of such  expenditure  to but
excluding  the  date  such  expenditure  is paid in  full.  Notwithstanding  the
foregoing,  it is expressly agreed that neither the Administrative Agent nor any
Lender shall have any liability or  responsibility  for the  performance  of any
obligation of Borrower under this Agreement or any of the other Loan Documents.


<PAGE>


                     ARTICLE XII -- THE ADMINISTRATIVE AGENT

         Section 12.1 Appointment,  Powers and Immunities.  In order to expedite
the various  transactions  contemplated  by this  agreement,  the Lenders hereby
irrevocably appoint and authorize Bank of America to act as their Administrative
Agent  hereunder  and under  each of the other Loan  Documents.  Bank of America
consents  to  such   appointment  and  agrees  to  perform  the  duties  of  the
Administrative  Agent as specified herein.  The Lenders authorize and direct the
Administrative Agent to take such action in their name and on their behalf under
the terms and  provisions of the Loan  Documents and to exercise such rights and
powers  thereunder  as  are  specifically   delegated  to  or  required  of  the
Administrative  Agent for the Lenders,  together  with such rights and powers as
are reasonably  incidental thereto. The Administrative Agent is hereby expressly
authorized to act as the Administrative  Agent on behalf of itself and the other
Lenders:

                  (a) To receive on behalf of each of the Lenders any payment of
         principal,  interest,  fees or  other  amounts  paid  pursuant  to this
         Agreement  and the Notes and to  distribute to each Lender its pro rata
         share of all payments so received as provided in this Agreement;

               (b) To receive all documents and items to be furnished  under the
          Loan Documents;

               (c) To act as  nominee  for and on behalf of the  Lenders  in and
          under the Loan Documents;

               (d) To arrange for the means whereby the funds of the Lenders are
          to be made available to Borrower;

                  (e)  To  distribute  to  the  Lenders  information,  requests,
         notices, payments, prepayments, documents and other items received from
         Borrower, the other Obligated Parties, and other Persons;

                  (f) To execute and deliver to  Borrower,  the other  Obligated
         Parties, and other Persons, all requests, demands, approvals,  notices,
         and consents received from the Lenders;

               (g) To the extent permitted by the Loan Documents, to exercise on
          behalf of each Lender all rights and  remedies of the Lenders upon the
          occurrence of any Event of Default;

                  (h) To accept,  execute,  and  deliver the  Borrower  Security
         Agreement,  the Guarantor Security  Agreements,  the Pledge Agreements,
         and any other security documents as the secured party; and

               (i) To  take  such  other  actions  as may  be  requested  by the
          Required Lenders.


<PAGE>


         Neither the Administrative  Agent nor any of its Affiliates,  officers,
directors, employees, attorneys, or agents shall be liable to any Lender for any
action  taken or omitted to be taken by any of them  hereunder  or  otherwise in
connection with this Agreement or any of the other Loan Documents (INCLUDING ANY
ACTION TAKEN OR OMITTED TO BE TAKEN BY SUCH PARTIES NEGLIGENTLY),  but excluding
such actions or omissions  arising from such  parties' own gross  negligence  or
willful  misconduct.  Without limiting the generality of the preceding sentence,
the  Administrative  Agent:  (i) may treat  the payee of any Note as the  holder
thereof until the Administrative Agent receives written notice of the assignment
or  transfer  thereof  signed  by such  payee  and in form  satisfactory  to the
Administrative Agent; (ii) shall have no duties or responsibilities except those
expressly set forth in this  Agreement and the other Loan  Documents,  and shall
not by reason of this  Agreement  or any other  Loan  Document  be a trustee  or
fiduciary for any Lender; (iii) shall not be required to initiate any litigation
or collection  proceedings  hereunder or under any other Loan Document except to
the extent requested by the Required  Lenders;  (iv) shall not be responsible to
the  Lenders  for  any  recitals,  statements,   representations  or  warranties
contained in this  Agreement or any other Loan Document,  or any  certificate or
other document referred to or provided for in, or received by any of them under,
this  Agreement  or any  other  Loan  Document,  or  for  the  value,  validity,
effectiveness,  enforceability,  or  sufficiency  of this Agreement or any other
Loan  Document  or any other  document  referred  to or  provided  for herein or
therein  or for any  failure by any  Person to  perform  any of its  obligations
hereunder or thereunder;  (v) may consult with legal counsel  (including counsel
for Borrower),  independent public accountants, and other experts selected by it
and shall not be liable  for any  action  taken or  omitted  to be taken in good
faith by it in  accordance  with the  advice of such  counsel,  accountants,  or
experts;  and (vi)  shall  incur no  liability  under or in  respect of any Loan
Document by acting upon any notice, consent, certificate, or other instrument or
writing  believed by it to be genuine and signed or sent by the proper  party or
parties.  As to any matters not expressly  provided for by this  Agreement,  the
Administrative  Agent  shall in all cases be fully  protected  in acting,  or in
refraining from acting, here under in accordance with instructions signed by the
Required  Lenders,  and such instructions of the Required Lenders and any action
taken or failure to act pursuant thereto shall be binding on all of the Lenders;
provided,  however,  that the Administrative Agent shall not be required to take
any action which exposes the Administrative Agent to personal liability or which
is contrary to this Agreement or any other Loan Document or applicable law.

         Section 12.2 Rights of Administrative  Agent as a Lender.  With respect
to its  Commitment,  the Advances  made by it and the Note issued to it, Bank of
America in its  capacity  as a Lender  hereunder  shall have the same rights and
powers hereunder as any other Lender and may exercise the same as though it were
not acting as the  Administrative  Agent,  and the term  "Lender"  or  "Lenders"
shall, unless the context otherwise indicates,  include the Administrative Agent
in its  individual  capacity.  The  Administrative  Agent and its Affiliates may
(without  having to account  therefor to any Lender) accept  deposits from, lend
money to, act as trustee under  indentures of, provide merchant banking services
to, and generally  engage in any kind of business with Borrower,  any Subsidiary
of Borrower, any other Obligated Party, and any other Person who may do business
with or own securities of Borrower or any other  Obligated  Party,  all as if it
were not  acting as the  Administrative  Agent and  without  any duty to account
therefor to the Lenders.

         Section 12.3  Sharing of Payments,  Etc. If any Lender shall obtain any
payment of any  principal  of or interest  on any Advance  made by it under this
Agreement or payment of any other  obligation under the Loan Documents then owed
by Borrower or any other  Obligated  Party to such  Lender,  whether  voluntary,
involuntary,  through  the  exercise  of any  right of  setoff,  lender's  lien,
counterclaim  or similar right,  or otherwise,  in excess of its pro rata share,
such Lender shall promptly purchase from the other Lenders participations in the
Advances held by them hereunder in such amounts, and make such other adjustments
from time to time as shall be necessary to cause such purchasing Lender to share
the excess payment ratably with each of the other Lenders in accordance with its
pro rata portion thereof. To such end, all of the Lenders shall make appropriate
adjustments among themselves (by the resale of participations sold or otherwise)
if all or any portion of such excess  payment is  thereafter  rescinded  or must
otherwise be restored. Borrower agrees, to the fullest extent it may effectively
do so under applicable law, that any Lender so purchasing a participation in the
Advances made by the other  Lenders may exercise all rights of setoff,  lender's
lien,  counterclaim,  or similar  rights with respect to such  participation  as
fully as if such  Lender  were a direct  holder of  Advances  to Borrower in the
amount of such participation.  Nothing contained herein shall require any Lender
to exercise  any such right or shall affect the right of any Lender to exercise,
and retain the benefits of exercising,  any such right with respect to any other
indebtedness or obligation of Borrower.


<PAGE>


         Section 12.4 Indemnification. THE LENDERS HEREBY AGREE TO INDEMNIFY THE
AGENTS FROM AND HOLD THE AGENTS  HARMLESS  AGAINST (TO THE EXTENT NOT REIMBURSED
UNDER SECTIONS 13.1 AND 13.2, BUT WITHOUT  LIMITING THE  OBLIGATIONS OF BORROWER
UNDER  SECTIONS  13.1 AND 13.2),  RATABLY IN  ACCORDANCE  WITH THEIR  RESPECTIVE
COMMITMENTS, ANY AND ALL LIABILITIES,  OBLIGATIONS,  LOSSES, DAMAGES, PENALTIES,
ACTIONS, JUDGMENTS,  DEFICIENCIES,  SUITS, COSTS, EXPENSES (INCLUDING ATTORNEYS'
FEES), AND  DISBURSEMENTS OF ANY KIND OR NATURE  WHATSOEVER WHICH MAY BE IMPOSED
ON, INCURRED BY, OR ASSERTED AGAINST ANY AGENT IN ANY WAY RELATING TO OR ARISING
OUT OF ANY OF THE LOAN  DOCUMENTS  OR ANY ACTION TAKEN OR OMITTED TO BE TAKEN BY
ANY AGENT UNDER OR IN RESPECT OF ANY OF THE LOAN DOCUMENTS INCLUDING ANY PORTION
OF THE  FOREGOING TO THE EXTENT  CAUSED BY THE ANY AGENT'S SOLE OR  CONTRIBUTORY
NEGLIGENCE; PROVIDED, FURTHER, THAT NO LENDER SHALL BE LIABLE FOR ANY PORTION OF
THE FOREGOING TO THE EXTENT  CAUSED BY ANY AGENT'S  GROSS  NEGLIGENCE OR WILLFUL
MISCONDUCT.  WITHOUT LIMITATION OF THE FOREGOING, IT IS THE EXPRESS INTENTION OF
THE  LENDERS  THAT THE  AGENTS  SHALL  BE  INDEMNIFIED  HEREUNDER  FROM AND HELD
HARMLESS  AGAINST  ALL  OF  SUCH  LIABILITIES,   OBLIGATIONS,  LOSSES,  DAMAGES,
PENALTIES, ACTIONS, JUDGMENTS,  DEFICIENCIES,  SUITS, COSTS, EXPENSES (INCLUDING
ATTORNEYS' FEES), AND DISBURSEMENTS OF ANY KIND OR NATURE DIRECTLY OR INDIRECTLY
ARISING OUT OF OR  RESULTING  FROM THE SOLE OR  CONTRIBUTORY  NEGLIGENCE  OF THE
AGENTS. WITHOUT LIMITING ANY OTHER PROVISION OF THIS SECTION, EACH LENDER AGREES
TO REIMBURSE EACH AGENT PROMPTLY UPON DEMAND FOR ITS PRO RATA SHARE  (CALCULATED
ON THE  BASIS  OF  THE  COMMITMENTS)  OF  ANY  AND  ALL  OUT-OF-POCKET  EXPENSES
(INCLUDING  ATTORNEYS'  FEES)  INCURRED  BY THE  AGENTS IN  CONNECTION  WITH THE
PREPARATION,  EXECUTION, DELIVERY,  ADMINISTRATION,  MODIFICATION,  AMENDMENT OR
ENFORCEMENT (WHETHER THROUGH NEGOTIATIONS,  LEGAL PROCEEDINGS, OR OTHERWISE) OF,
OR LEGAL  ADVICE  IN  RESPECT  OF  RIGHTS OR  RESPONSIBILITIES  UNDER,  THE LOAN
DOCUMENTS,  TO THE EXTENT THAT SUCH AGENT IS NOT REIMBURSED FOR SUCH EXPENSES BY
BORROWER.

         Section 12.5 Independent  Credit Decisions.  Each Lender agrees that it
has  independently  and without  reliance on any Agent or any other Lender,  and
based on such documents and information as it has deemed  appropriate,  made its
own credit  analysis of Borrower and decision to enter into this  Agreement  and
that it will,  independently  and without  reliance  upon any Agent or any other
Lender,  and  based  upon  such  documents  and  information  as it  shall  deem
appropriate  at the time,  continue to make its own  analysis  and  decisions in
taking or not  taking  action  under  this  Agreement  or any of the other  Loan
Documents.  The  Administrative  Agent  shall  not be  required  to keep  itself
informed as to the  performance or observance by Borrower or any Obligated Party
of this  Agreement or any other Loan  Document or to inspect the  properties  or
books of Borrower or any Obligated Party. Except for notices,  reports and other
documents and information  expressly  required to be furnished to the Lenders by
the  Administrative  Agent  hereunder  or under the other  Loan  Documents,  the
Administrative  Agent shall not have any duty or  responsibility  to provide any
Lender with any credit or other  financial  information  concerning the affairs,
financial  condition or business of Borrower or any  Obligated  Party (or any of
their Affiliates) which may come into the possession of the Administrative Agent
or any of its Affiliates.


<PAGE>


         Section 12.6 Several Commitments. The Commitments and other obligations
of the Lenders under this  Agreement  are several.  The default by any Lender in
making an Advance in accordance with its Commitment  shall not relieve the other
Lenders of their obligations  under this Agreement.  In the event of any default
by any  Lender  in  making  any  Advance,  each  nondefaulting  Lender  shall be
obligated  to make its Advance but shall not be  obligated to advance the amount
which the defaulting Lender was required to advance hereunder. In no event shall
any  Lender be  required  to advance  an amount or  amounts  which  shall in the
aggregate  exceed such Lender's  Commitment.  No Lender shall be responsible for
any act or omission of any other Lender.

         Section 12.7 Successor Administrative Agent. Subject to the appointment
and  acceptance  of a  successor  Administrative  Agent as provided  below,  the
Administrative  Agent may  resign at any time by giving  notice  thereof  to the
Lenders and  Borrower  and the  Administrative  Agent may be removed at any time
with or without  cause by the Required  Lenders.  Upon any such  resignation  or
removal,  the  Required  Lenders  will  have the right to  appoint  a  successor
Administrative   Agent  from  among  the  remaining  Lenders.  If  no  successor
Administrative  Agent shall have been so appointed  by the Required  Lenders and
shall have accepted such appointment  within thirty (30) days after the retiring
Administrative  Agent's giving of notice of resignation or the Required Lenders'
removal of the retiring  Administrative Agent, then the retiring  Administrative
Agent may, on behalf of the Lenders,  appoint a successor  Administrative Agent,
which shall be a commercial  bank organized  under the laws of the United States
of America or any State  thereof and having  combined  capital and surplus of at
least  One  Billion  Dollars  ($1,000,000,000).   Upon  the  acceptance  of  its
appointment as successor  Administrative  Agent,  such successor  Administrative
Agent shall  thereupon  succeed to and become  vested  with all rights,  powers,
privileges,  immunities,  and duties of the resigning or removed  Administrative
Agent,  and the  resigning or removed  Administrative  Agent shall be discharged
from its  duties  and  obligations  under  this  Agreement  and the  other  Loan
Documents.   After  any  Administrative   Agent's   resignation  or  removal  as
Administrative  Agent,  the  provisions  of this  Article XII shall  continue in
effect for its benefit in respect of any actions taken or omitted to be taken by
it while it was the Administrative Agent.

         Section 12.8      Independent Contractor.

         (a) The relationship between each Agent and each of the Lenders is that
of an  independent  contractor.  The use of the term "Agent" is for  convenience
only  and  is  used  to  describe,  as a form  of  convention,  the  independent
contractual  relationship  between each Agent and each of the  Lenders.  Nothing
contained in this  Agreement or the other Loan  Documents  shall be construed to
create an agency,  trust or other fiduciary  relationship  between any Agent and
any of the Lenders.

         (b) As an independent  contractor  empowered by the Lenders to exercise
certain  rights and perform  certain duties and  responsibilities  hereunder and
under the other Loan  Documents,  the  Administrative  Agent is  nevertheless  a
"representative"  of the  Lenders,  as that term is  defined in Article 1 of the
Uniform  Commercial Code, for purposes of actions for the benefit of the Lenders
and the  Administrative  Agent  with  respect  to all  collateral  security  and
guaranties  contemplated  by  the  Loan  Documents.  Such  actions  include  the
designation of the Administration  Agent as "secured party,"  "mortgagee" or the
like on all financing  statements and other documents and  instruments,  whether
recorded or  otherwise,  relating  to the  attachment,  perfection,  priority or
enforcement of any security interests, mortgages or deeds of trust in collateral
security   intended  to  secure  the  payment  or  performance  of  any  of  the
Obligations, all for the benefit of the Lenders and the Administrative Agent.


<PAGE>


                          ARTICLE XIII -- MISCELLANEOUS

         Section 13.1 Expenses. Borrower hereby agrees to pay on demand: (a) all
reasonable  costs and expenses of the Agents in connection with the preparation,
negotiation,  syndication,  execution,  and delivery of this  Agreement  and the
other  Loan  Documents  including,   without  limitation,  the  legal  fees  and
reasonable  expenses of legal counsel for the Agents;  (b) all reasonable  costs
and  expenses  of  the  Agents  in  connection  with  any  and  all  amendments,
modifications,   renewals,  extensions  and  supplements  of  any  of  the  Loan
Documents;  (c) all reasonable  costs and expenses of the Agents and the Lenders
in connection with any Default, including any work-outs,  amendments to any Loan
Documents,  or  negotiations  related  thereto,  and  the  enforcement  of  this
Agreement or any other Loan Document,  including,  without limitation,  the fees
and expenses of legal counsel and  professional  advisors for the Agents and the
Lenders;  (d)  all  transfer,  stamp,  documentary,   or  other  similar  taxes,
assessments,  or charges levied by any Governmental Authority in respect of this
Agreement  or any  of  the  other  Loan  Documents;  (e)  all  costs,  expenses,
assessments,   and  other  charges  incurred  in  connection  with  any  filing,
registration,  recording,  or  perfection  of  any  security  interest  or  Lien
contemplated  by this  Agreement or any other Loan  Document;  and (f) all other
reasonable  costs and expenses  incurred by the Agents in  connection  with this
Agreement or any other Loan Document,  including, without limitation, all costs,
expenses,  and other charges incurred in connection with obtaining any mortgagee
title insurance policy,  survey, audit,  appraisal in respect of the Collateral,
and other out-of-pocket costs and expenses.

         Section 13.2  Indemnification.  BORROWER SHALL INDEMNIFY THE AGENTS AND
EACH LENDER AND EACH AFFILIATE THEREOF AND THEIR RESPECTIVE OFFICERS, DIRECTORS,
EMPLOYEES,  ATTORNEYS,  AND AGENTS FROM, AND HOLD EACH OF THEM HARMLESS AGAINST,
ANY  AND  ALL  LOSSES,  LIABILITIES,   CLAIMS,  DAMAGES,  PENALTIES,  JUDGMENTS,
DISBURSEMENTS,  COSTS, AND EXPENSES  (INCLUDING  REASONABLE  ATTORNEYS' FEES) TO
WHICH ANY OF THEM MAY BECOME SUBJECT WHICH DIRECTLY OR INDIRECTLY  ARISE FROM OR
RELATE TO (A) THE NEGOTIATION, EXECUTION, DELIVERY, PERFORMANCE, ADMINISTRATION,
OR  ENFORCEMENT  OF ANY OF  THE  LOAN  DOCUMENTS,  (B)  ANY OF THE  TRANSACTIONS
CONTEMPLATED  BY  THE  LOAN  DOCUMENTS,  (C)  ANY  BREACH  BY  BORROWER  OF  ANY
REPRESENTATION,  WARRANTY,  COVENANT, OR OTHER AGREEMENT CONTAINED IN ANY OF THE
LOAN  DOCUMENTS,  (D)  THE  PRESENCE,  RELEASE,  THREATENED  RELEASE,  DISPOSAL,
REMOVAL,  OR CLEANUP OF ANY HAZARDOUS  MATERIAL  LOCATED ON, ABOUT,  WITHIN,  OR
AFFECTING  ANY OF THE  PROPERTIES  OR ASSETS OF  BORROWER OR ANY  SUBSIDIARY  OF
BORROWER, OR (E) ANY INVESTIGATION,  LITIGATION, OR OTHER PROCEEDING, INCLUDING,
WITHOUT  LIMITATION,   ANY  THREATENED   INVESTIGATION,   LITIGATION,  OR  OTHER
PROCEEDING  RELATING TO ANY OF THE  FOREGOING.  WITHOUT  LIMITING THE FOREGOING,
THIS INDEMNITY SHALL APPLY TO ANY LOSS, LIABILITY,  OBLIGATION, DAMAGE, PENALTY,
JUDGMENT,  CLAIM,  DEFICIENCY  OR EXPENSE  ARISING OUT OF THE SOLE OR CONCURRENT
NEGLIGENCE  OF ANY AGENT OR ANY  LENDER,  BUT AS TO ANY  AGENT OR  LENDER  SHALL
EXCLUDE ANY LOSS,  LIABILITY,  OBLIGATION,  DAMAGE,  PENALTY,  JUDGMENT,  CLAIM,
DEFICIENCY  OR  EXPENSE  ARISING  BY REASON OF THE GROSS  NEGLIGENCE  OR WILLFUL
MISCONDUCT OF SUCH AGENT OR LENDER.


<PAGE>


         Section 13.3 No Duty. All attorneys, accountants, appraisers, and other
professional  Persons  and  consultants  retained  by the Agents and the Lenders
shall have the right to act  exclusively  in the  interest of the Agents and the
Lenders and shall have no duty of disclosure,  duty of loyalty, duty of care, or
other duty or  obligation  of any type or nature  whatsoever  to  Borrower,  any
shareholder or Subsidiary of Borrower or any other Person.

         Section  13.4  No  Fiduciary  Relationship.  The  relationship  between
Borrower and each Lender is solely that of debtor and creditor,  and none of the
Agents nor any of the Lenders has any  fiduciary or other  special  relationship
with Borrower,  and no term or condition of any of the Loan  Documents  shall be
construed so as to deem the  relationship  between Borrower and any Lender to be
other than that of debtor and creditor.

         Section 13.5 No Waiver;  Cumulative Remedies. No failure on the part of
the Agents or any Lender to exercise and no delay in  exercising,  and no course
of dealing with respect to, any right,  power, or privilege under this Agreement
shall operate as a waiver thereof,  nor shall any single or partial  exercise of
any right,  power,  or  privilege  under this  Agreement  preclude  any other or
further  exercise  thereof  or  the  exercise  of any  other  right,  power,  or
privilege.  The rights and remedies provided for in this Agreement and the other
Loan  Documents  are  cumulative  and not  exclusive  of any rights and remedies
provided by law.

         Section 13.6      Successors and Assigns.

         (a) This  Agreement  shall be binding  upon and inure to the benefit of
the parties hereto and their respective successors and assigns. Borrower may not
assign or transfer any of its rights or obligations  hereunder without the prior
written consent of the Administrative  Agent and all of the Lenders.  Any Lender
may sell  participations to one or more banks or other institutions in or to all
or a portion of its rights and  obligations  under this  Agreement and the other
Loan  Documents  (including,  without  limitation,  all  or  a  portion  of  its
Commitments  and the Advances  owing to it);  provided,  however,  that (i) such
Lender's   obligations  under  this  Agreement  and  the  other  Loan  Documents
(including,  without limitation,  its Commitments) shall remain unchanged,  (ii)
such Lender shall remain solely  responsible to Borrower for the  performance of
such obligations, (iii) such Lender shall remain the holder of its Notes for all
purposes of this  Agreement,  (iv)  Borrower  shall  continue to deal solely and
directly  with  such  Lender  in  connection   with  such  Lender's  rights  and
obligations  under this  Agreement  and the other Loan  Documents,  and (v) such
Lender shall not sell a participation  that conveys to the participant the right
to vote or give or  withhold  consents  under this  Agreement  or any other Loan
Document,  other than the right to vote upon or consent to (A) any  increase  of
such Lender's  Commitments,  (B) any  reduction of the  principal  amount of, or
interest to be paid on, the  Advances of such Lender,  (C) any  reduction of any
commitment  fee or other amount  payable to such Lender under any Loan Document,
or (D) any  postponement  of any date for the  payment of any amount  payable in
respect of the Advances of such Lender.


<PAGE>


         (b)  Borrower  and  each of the  Lenders  agree  that  any  Lender  (an
"Assigning  Lender")  may at any time assign to one or more  Eligible  Assignees
all, or a portion of all, of its rights and obligations under this Agreement and
the other Loan  Documents  (including,  without  limitation,  its Commitment and
Advances) (each an "Assignee");  provided,  however, that (i) except in the case
of an  assignment  of  all of a  Lender's  rights  and  obligations  under  this
Agreement and the other Loan Documents,  or as otherwise  acceptable to Borrower
and the  Administrative  Agent the amount of the  Commitments  of the  assigning
Lender being assigned pursuant to each assignment  (determined as of the date of
the Assignment and Acceptance with respect to such assignment) shall in no event
be less than  $5,000,000.00,  and (ii) the parties to each such assignment shall
execute and deliver to the Administrative Agent for its acceptance and recording
in the Register (as defined below), an Assignment and Acceptance,  together with
the Note subject to such  assignment,  and a processing and  recordation  fee of
$3,500.00. Upon such execution,  delivery,  acceptance,  and recording, from and
after the effective date  specified in each  Assignment  and  Acceptance,  which
effective  date shall be at least  five (5)  Business  Days after the  execution
thereof,  or, if so specified in such  Assignment  and  Acceptance,  the date of
acceptance  thereof by the  Administrative  Agent,  (x) the assignee  thereunder
shall be a party  hereto as a  "Lender"  and,  to the  extent  that  rights  and
obligations  hereunder have been assigned to it pursuant to such  Assignment and
Acceptance,  have the rights and obligations of a Lender hereunder and under the
Loan Documents and (y) the Lender that is an assignor  thereunder  shall, to the
extent that rights and  obligations  hereunder have been assigned by it pursuant
to such  Assignment and  Acceptance,  relinquish its rights and be released from
its  obligations  under this Agreement and the other Loan Documents (and, in the
case of an Assignment and Acceptance  covering all or the remaining portion of a
Lender's  rights and  obligations  under the Loan  Documents,  such Lender shall
cease to be a party  thereto).  The  provisions  of Article IV and Section  13.2
shall continue with respect to such Assigning Lender.

         (c) By executing  and  delivering  an Assignment  and  Acceptance,  the
Assigning  Lender and its Assignee  confirm to and agree with each other and the
other parties hereto as follows:  (i) other than as provided in such  Assignment
and Acceptance,  such Assigning Lender makes no  representation  or warranty and
assumes  no  responsibility  with  respect  to any  statements,  warranties,  or
representations  made  in or in  connection  with  the  Loan  Documents  or  the
execution, legality, validity, and enforceability,  genuineness, sufficiency, or
value of the Loan  Documents  or any  other  instrument  or  document  furnished
pursuant thereto; (ii) such Assigning Lender makes no representation or warranty
and  assumes no  responsibility  with  respect  to the  financial  condition  of
Borrower or any Obligated  Party or the performance or observance by Borrower or
any  Obligated  Party of its  obligations  under the Loan  Documents;  (iii) the
Assignee  confirms that it has received copies of the Loan  Documents,  together
with  copies of the  financial  statements  referred  to in Section 7.2 and such
other  documents and  information  as it has deemed  appropriate to make its own
credit analysis and decision to enter into such Assignment and Acceptance;  (iv)
the Assignee will,  independently  and without reliance upon the  Administrative
Agent or such assignor and based on such  documents and  information as it shall
deem  appropriate  at the time,  continue  to make its own credit  decisions  in
taking or not taking action under this  Agreement and the other Loan  Documents;
(v) the Assignee  confirms  that it is an Eligible  Assignee;  (vi) the Assignee
appoints  and  authorizes  the  Administrative  Agent  to take  such  action  as
Administrative  Agent on its  behalf and  exercise  such  powers  under the Loan
Documents as are  delegated to the  Administrative  Agent by the terms  thereof,
together with such powers as are reasonably  incidental  thereto;  and (vii) the
Assignee  agrees that it will perform in accordance  with their terms all of the
obligations  which  by the  terms  of the  Loan  Documents  are  required  to be
performed by it as a Lender.

         (d) The  Administrative  Agent shall maintain at its Principal Office a
copy of each  Assignment  and  Acceptance  delivered to and accepted by it and a
register for the  recordation  of the names and addresses of the Lenders and the
Commitment  of, and principal  amount of the Advances owing to, each Lender from
time to time (the  "Register").  The entries in the Register shall be conclusive
and  binding  for  all  purposes,  absent  manifest  error,  and  Borrower,  the
Administrative  Agent,  and the  Lenders  may treat  each  Person  whose name is
recorded in the Register as a Lender  hereunder for all purposes  under the Loan
Documents.  The Register  shall be available  for  inspection by Borrower or any
Lender  at any  reasonable  time and from  time to time  upon  reasonable  prior
notice.


<PAGE>


         (e) Upon its receipt of an  Assignment  and  Acceptance  executed by an
assigning Lender and Assignee  representing  that it is an Eligible Assignee (or
other  assignee  permitted  hereunder),  together  with any Note subject to such
assignment,  the  Administrative  Agent shall, if such Assignment and Acceptance
has been  completed  and is in  substantially  the form of Exhibit B, (i) accept
such Assignment and Acceptance, (ii) record the information contained therein in
the Register,  and (iii) give prompt written notice thereof to Borrower.  Within
five (5)  Business  Days after its  receipt  of such  notice,  Borrower,  at its
expense,  shall execute and deliver to the Administrative  Agent in exchange for
the surrendered Note a new Note to the order of such Eligible Assignee (or other
assignee  permitted  hereunder)  in an  amount  equal  to  the  portion  of  the
Commitments assumed by it pursuant to such Assignment and Acceptance and, if the
Assigning  Lender has retained a portion of the  Commitments,  a new Note to the
order  of  the  Assigning  Lender  in an  amount  equal  to the  portion  of the
Commitments retained by it hereunder (each such promissory note shall constitute
a "Note" for  purposes  of the Loan  Documents).  Such new Notes  shall be in an
aggregate principal amount of the surrendered Note, shall be dated the effective
date of such Assignment and Acceptance,  and shall otherwise be in substantially
the form of Exhibit C.

         (f) Any Lender may, in connection with any assignment or  participation
or proposed  assignment or participation  pursuant to this Section,  disclose to
the Assignee or participant or proposed Assignee or participant, any information
relating to Borrower or any Subsidiary of Borrower  furnished to such, Lender by
or on behalf of Borrower or any of its Subsidiaries.

         (g)  Notwithstanding  any other term of this Agreement to the contrary,
any Lender may  (without  requesting  the  consent of either the  Administrative
Agent or  Borrower)  pledge  its Notes to a Federal  Reserve  Bank in support of
borrowings made by such Lender from such Federal Reserve Bank.

         (h)  Notwithstanding  any other term of this Agreement to the contrary,
any Lender may assign all,  or a portion of all,  of its rights and  obligations
under  this  Agreement  and  the  other  Loan  Documents   (including,   without
limitation,  its  Commitment and Advances) to an Affiliate of such Lender or any
other Lender provided that:

                  (i) such assignor  Lender has obtained the written  consent of
         the  Administrative  Agent  (which  consent  shall not be  unreasonably
         delayed or withheld)  if the effect of such  assignment  or  delegation
         shall entitle such Affiliate or other Lender to claim compensation from
         Borrower pursuant to Article IV; and

                  (ii) in every other case,  such assignor  Lender has furnished
         notice to, but not obtained the consent of, the Administrative Agent.

         Section 13.7 Survival.  All representations and warranties made in this
Agreement  or  any  other  Loan  Document  or in  any  document,  statement,  or
certificate  furnished  in  connection  with this  Agreement  shall  survive the
execution and delivery of this Agreement and the other Loan Documents  until the
Obligations  have been paid and performed in full, and no  investigation  by the
Administrative   Agent  or  any  Lender  or  any   closing   shall   affect  the
representations  and warranties or the right of the Administrative  Agent or any
Lender  to rely  upon  them.  Without  prejudice  to the  survival  of any other
obligation of Borrower  hereunder,  the obligations of Borrower under Article IV
and Sections 13.1 and 13.2 shall survive  repayment of the Notes and termination
of the Commitments.  The obligations of the Administrative Agent and the Lenders
under Section 13.18 shall survive  repayment of the Notes and termination of the
Commitments.

         Section 13.8 ENTIRE AGREEMENT. THIS AGREEMENT, THE NOTES, AND THE OTHER
LOAN DOCUMENTS  REFERRED TO HEREIN EMBODY THE FINAL,  ENTIRE AGREEMENT AMONG THE
PARTIES  HERETO  AND  SUPERSEDE  ANY  AND  ALL  PRIOR  COMMITMENTS,  AGREEMENTS,
REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER WRITTEN OR ORAL, RELATING TO THE
SUBJECT  MATTER  HEREOF AND MAY NOT BE  CONTRADICTED  OR VARIED BY  EVIDENCE  OF
PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT  ORAL  AGREEMENTS OR  DISCUSSIONS OF THE
PARTIES HERETO. THERE ARE NO ORAL AGREEMENTS AMONG THE PARTIES HERETO.


<PAGE>


         Section 13.9  Amendments,  Etc. No amendment or waiver of any provision
of this Agreement,  the Notes, or any other Loan Document to which Borrower is a
party,  nor any consent to any  departure  by Borrower  therefrom,  shall in any
event be  effective  unless  the same  shall be  agreed or  consented  to by the
Required  Lenders  and  Borrower,  and each  such  waiver  or  consent  shall be
effective only in the specific  instance and for the specific  purpose for which
given; provided, that no amendment,  waiver, or consent shall, unless in writing
and signed by all of the  Lenders and  Borrower,  do any of the  following:  (a)
increase  Commitments  of the Lenders or subject  the Lenders to any  additional
obligations;  (b) reduce the principal of, or interest on, the Notes or any fees
or other  amounts  payable to the Lenders,  (but not the  Administrative  Agent)
hereunder; (c) alter the allocation among Lenders of, or postpone any date fixed
for any payment or  prepayment  (whether or not  mandatory)  of principal of, or
interest  on,  the  Notes  or  any  fees  or  other   amounts   payable  to  the
Administrative Agent or the Lenders hereunder;  (d) change the percentage of the
Commitments  or of the  aggregate  unpaid  principal  amount of the Notes or the
number of Lenders which shall be required for the Lenders or any of them to take
any action  under this  Agreement;  (e) change any  provision  contained in this
Section 13.9; or (f) release any material  Guarantor or any material  portion of
the   Collateral,   except  in  accordance  with  the  relevant  Loan  Document.
Notwithstanding   anything  to  the  contrary  contained  in  this  Section,  no
amendment,  waiver, or consent shall be made with respect to Article XII without
the prior written consent of the Administrative Agent.

         Section  13.10  Maximum  Interest  Rate.  Regardless  of any  provision
contained  in any Loan  Document,  neither  Administrative  Agent nor any Lender
shall ever be entitled to contract  for,  charge,  take,  reserve,  receive,  or
apply, as interest on all or any part of the  Obligations,  any amount in excess
of the  Maximum  Rate,  and, if Lenders  ever do so,  then such excess  shall be
deemed a partial  prepayment of principal and treated  hereunder as such and any
remaining  excess shall be refunded to Borrower.  In determining if the interest
paid or payable  exceeds the Maximum Rate,  Borrower and Lenders  shall,  to the
maximum extent  permitted under  applicable Law, (a) treat all Advances as but a
single extension of credit (and Lenders and Borrower agree that such is the case
and that provision  herein for multiple  Advances is for convenience  only), (b)
characterize any nonprincipal payment as an expense, fee, or premium rather than
as interest,  (c) exclude voluntary prepayments and the effects thereof, and (d)
amortize,  prorate, allocate, and spread the total amount of interest throughout
the entire contemplated term of the Obligations. However, if the Obligations are
paid  and  performed  in full  prior to the end of the  full  contemplated  term
thereof, and if the interest received for the actual period of existence thereof
exceeds the Maximum  Amount,  Lenders  shall  refund such  excess,  and, in such
event,  Lenders  shall not,  to the extent  permitted  by Law, be subject to any
penalties provided by any laws for contracting for, charging, taking, reserving,
or receiving interest in excess of the Maximum Amount. The "Maximum Rate" or the
"Maximum  Amount,"  mean the "weekly  ceiling" from time to time in effect under
Texas Finance Code ss. 303.305, as amended.

         Section 13.11 Notices.  All notices and other  communications  provided
for in this  Agreement and the other Loan Documents to which Borrower is a party
shall be given or made by  telecopy  or in  writing  and  telecopied,  mailed by
certified mail return receipt requested,  or delivered to the intended recipient
at the "Address for Notices"  specified  below its name on the  signature  pages
hereof, or, as to any party at such other address as shall be designated by such
party in a notice to each other party  given in  accordance  with this  Section.
Except as otherwise provided in this Agreement, all such communications shall be
deemed to have  been  duly  given  when  transmitted  by  telecopy,  subject  to
telephone  confirmation of receipt, or when personally delivered or, in the case
of a mailed  notice,  when duly  deposited  in the mails,  in each case given or
addressed as aforesaid;  provided,  however, notices to the Administrative Agent
pursuant  to  Article  II  shall  not  be  effective   until   received  by  the
Administrative Agent.


<PAGE>


         Section 13.12  Governing Law. THIS  AGREEMENT  SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.

         Section 13.13  Counterparts.  This  Agreement may be executed in one or
more counterparts,  each of which shall be deemed an original,  but all of which
together shall constitute one and the same instrument.

         Section 13.14  Severability.  Any provision of this Agreement held by a
court of competent  jurisdiction to be invalid or unenforceable shall not impair
or invalidate  the remainder of this  Agreement and the effect  thereof shall be
confined to the provision held to be invalid or illegal.

     Section 13.15 Headings.  The headings,  captions,  and arrangements used in
this Agreement are for convenience only and shall not affect the  interpretation
of this Agreement.

         Section 13.16  Construction.  Borrower,  the Administrative  Agent, and
each Lender  acknowledges that each of them has had the benefit of legal counsel
of its own choice and has been afforded an  opportunity to review this Agreement
and the other Loan Documents with its legal counsel.

         Section 13.17 Independence of Covenants.  All covenants hereunder shall
be given  independent  effect so that if a particular action or condition is not
permitted  by any of such  covenants,  the fact that it would be permitted by an
exception to, or be otherwise  within the limitations of, another covenant shall
not avoid the  occurrence of a Default if such action is taken or such condition
exists.

         Section 13.18     Confidentiality.

         (a) The Agents and each Lender (each, a "Lending Party") agrees to keep
confidential  any Confidential  Information;  provided that nothing herein shall
prevent any Lending  Party from  disclosing  such  information  (a) to any other
Lending Party or any Affiliate of any Lending Party,  or any officer,  director,
employee, agent, or advisor of any Lending Party or any Affiliate of any Lending
Party, (b) to any other Person if reasonably incidental to the administration of
the credit  facility  provided  herein,  (c) as  required by any law,  rule,  or
regulation,  (d) upon the order of any court or administrative  agency, (e) upon
the request or demand of any regulatory  agency or authority,  (f) in connection
with any  litigation  to which  such  Lending  Party may be a party,  (g) to the
extent  necessary  in  connection  with the  exercise  of any remedy  under this
Agreement  or  any  other  Loan   Document,   and  (h)  subject  to   provisions
substantially  similar  to those  contained  in this  Section,  to any actual or
proposed   participant  or  Assignee.   Furthermore,   and  notwithstanding  the
foregoing,  no Lending Party shall provide any  Confidential  Information to any
officer,  director,  employee,  agent or advisor of any  Affiliate  of a Lending
Party if such officer, director,  employee, agent or advisor's position involves
the ability to transact  trades in, or solicit or accept orders for the purchase
or sale of, the common stock of Borrower.

         (b) The  Lending  Parties are aware that the United  States  securities
laws prohibit any Person who has received material,  non-public information such
as is the  subject of this  Section  13.18  from an issuer  from  purchasing  or
selling the securities of such issuer or from  communicating such information to
any other Person under circumstances in which it is reasonably  foreseeable that
such Person is likely to purchase or sell such securities.


<PAGE>


         (c) The Companies and the Lending  Parties agree that monetary  damages
would not be a  sufficient  remedy for any breach of this  Section  13.18 by the
Lending Parties and that, in addition to all other remedies, the Companies shall
be entitled to specific  performance and injunction or other equitable relief as
a remedy for any such breach.

         (d) The  restrictions  and  obligations  of this  Section  13.18  shall
survive the repayment of the  Obligations and shall continue to bind the Lending
Parties.

         Section 13.19  Restatement of Original  Credit  Agreement.  The parties
hereto agree that, after all conditions  precedent set forth in Section 6.1 have
been satisfied or waived:  (a) the Obligations  (as defined  herein)  represent,
among  other  things,  the  amendment,   extension,   and  modification  of  the
"Obligations" (as defined in the Original Credit Agreement);  (b) this Agreement
is intended to, and does hereby,  restate,  consolidate,  renew, extend,  amend,
modify,  supersede,  and replace the Original Credit  Agreement in its entirety;
(c) the Notes, if any, executed pursuant to this Agreement amend, renew, extend,
modify,  replace,  substitute  for, and supersede in their  entirety (but do not
extinguish,  the Debt arising under) the promissory notes issued pursuant to the
Original Credit Agreement,  which existing promissory notes shall be returned to
Administrative  Agent  promptly  after the Closing Date,  marked  "cancelled and
replaced," and, thereafter,  delivered by Administrative Agent to Borrower;  and
(d) the entering into and performance of their respective obligations under this
Agreement and the transactions evidenced hereby do not constitute a novation.

         Section 13.20  Assignments and Assumptions  Among Lenders.  The Lenders
hereby agree among  themselves  (and Borrower and  Guarantors  hereby consent to
such agreement) that,  concurrently  with the execution  hereof,  there shall be
deemed  to  have  occurred  assignments  and  assumptions  with  respect  to the
Obligations,  liens,  rights, and obligations under this Agreement and the other
Loan Documents (including, without limitation, the Commitments) such that, after
giving effect to such assignments and assumptions,  the Lender's Commitments are
as stated on  Schedule  1, and the  Lenders  hereby  make such  assignments  and
assumptions.

         Section 13.21 Waiver of Jury Trial. TO THE FULLEST EXTENT  PERMITTED BY
APPLICABLE LAW, BORROWER HEREBY  IRREVOCABLY AND EXPRESSLY WAIVES ALL RIGHT TO A
TRIAL BY JURY IN ANY ACTION,  PROCEEDING,  OR  COUNTERCLAIM  (WHETHER BASED UPON
CONTRACT,  TORT,  OR  OTHERWISE)  ARISING  OUT OF OR RELATING TO ANY OF THE LOAN
DOCUMENTS OR THE TRANSACTIONS  CONTEMPLATED  THEREBY OR THE ACTIONS OF ANY AGENT
OR ANY LENDER IN THE NEGOTIATION, ADMINISTRATION, OR ENFORCEMENT THEREOF.


<PAGE>


         Section  13.22  Choice of Forum;  Consent to  Service  of  Process  and
Jurisdiction.  Any suit,  action or proceeding  against Borrower with respect to
this Agreement or the Loan  Documents,  or any judgment  entered by any court in
respect  thereof,  may be brought  in the  courts of the State of Texas,  Travis
County,  or in the United  States courts  located in the State of Texas,  as the
Administrative  Agent shall,  at the direction of the Required  Lenders elect in
their sole discretion,  and Borrower  irrevocably  submits to the  non-exclusive
jurisdiction  of such courts for the purpose of any suit,  action or proceeding.
Borrower  irrevocably  consents to the service of process in any suit, action or
proceeding in said court by the mailing thereof by the  Administrative  Agent by
registered  or certified  mail,  postage  prepaid to  Borrower's  address  shown
opposite its name on the signature pages hereof. Nothing herein or in any of the
other Loan Documents shall affect the right of the Administrative Agent to serve
process in any other  manner  permitted  by law or shall  limit the right of the
Administrative  Agent to bring any action or proceeding against Borrower or with
respect  to any of its  property  in  courts  in other  jurisdictions.  Borrower
irrevocably  waives any objections  which it may now or hereafter have to laying
of venue of any suit,  action or  proceeding  arising out of or relating to this
Agreement or the other Loan Documents brought in the courts located in the State
of Texas,  Dallas County,  and hereby further  irrevocably waives any claim that
any such suit,  action or proceeding  brought in any such court has been brought
in any  inconvenient  forum.  Any action or proceeding  by Borrower  against the
Administrative  Agent or any Lender shall be brought only in a court  located in
Travis County, Texas.

         Section  13.23  Chapter 346.  Borrower  agrees that Chapter 346, of the
Texas Finance Code, as amended (which  regulates  certain  revolving credit loan
documents and revolving tri-party accounts) does not apply to the Obligations.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.

                             SIGNATURE PAGES FOLLOW.


<PAGE>



                   Fourth Amended and Restated Loan Agreement

                                 Signature Page

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

                                    BORROWER:

                                                PRIME MEDICAL SERVICES, INC.

                                                By:/s/ Teena E. Belcik
                                                       Teena E. Belcik
                                                       Vice President-Treasurer

                                                   Address for Notices:

                                                   1301 Capital of Texas Highway

                                                   Suite C-300
                                                   Austin, Texas 78746
                                                   Attention: Treasurer

                                                   Fax No.: (512) 328-8510
                                                   Telephone No.: (512) 314-4554




<PAGE>


                                                     BANK OF AMERICA:

                                                     BANK OF AMERICA, N.A.

                                            as Administrative Agent and a Lender

                                                 By: /s/ Daniel H. Penkar
                                                          Daniel H. Penkar
                                                          Senior Vice President

                                         Address for Notices:
                                         515 Congress Avenue, 11th Floor
                                         Post Office Box 908
                                         Austin, Texas  78701-0908
                                         Attention: Wade Morgan

                                         Fax No.: (512) 397-2052
                                         Telephone No.: (512) 397-2241

                                         Lending Office for Base Rate Advances:
                                         515 Congress Avenue, 11th Floor
                                         Post Office Box 908
                                         Austin, TX  78701-0908

                                         Lending Office for Eurodollar Advances:
                                         515 Congress Avenue, 11th Floor
                                         Post Office Box 908
                                         Austin, TX  78701-0908




<PAGE>


                                   BANKBOSTON:

                                           BANKBOSTON, N.A.,

                                           as Documentation Agent, and  a Lender

                                           By: /s/ Walter J. Marullo
                                                Walter J. Marullo
                                                Vice President

                                    Address for Notices:

                                    100 Federal Street, MS 01-08-05
                                    P.O. Box 2016
                                    Boston, Massachusetts 02106
                                    Attention: Walter J. Marullo, Vice President

                                            Fax No.: (617)  434-2472
                                            Telephone No.: (617)  434-2308

                                          Lending Office for Base Rate Advances:
                                           100 Federal Street
                                           P. 0. Box 2016
                                           Boston, MA  02106

                                         Lending Office for Eurodollar Advances:
                                           100 Federal Street
                                           P.O. Box 2016
                                           Boston, MA  02106


<PAGE>


                                                     BANK ONE, TEXAS, N.A.,

                                                         as Lender

                                               By: Edward W. Lick, Jr.
                                               Edward W. Lick, Jr.
                                               Vice President

                                                  Address for Notices:
                                                  221 West 6th Street, Suite 200
                                                  Austin, Texas 78701
                                                  Attention: Ed Lick

                                                  Fax No.: (512) 479-5720
                                                  Telephone No.: (512) 479-5730

                                         Lending Office for Base Rate Advances:
                                          Bank One, Austin
                                          221 West 6th Street, Suite 200
                                          Austin, TX  78701

                                         Lending Office for Eurodollar Advances:
                                          Bank One, Austin
                                          221 West 6th Street, Suite 200
                                          Austin, TX  78701



<PAGE>


                                         CREDIT LYONNAIS NEW YORK BRANCH

                                              as Lender

                                                     By: /s/ John Oberle
                                                              John Oberle
                                                              Vice President

                                                 Address for Notices:
                                                 1301 Avenue of the Americas
                                                 New York, New York 10019-6022
                                                 Attention: John Oberle

                                                 Fax No.: (212) 261-3440
                                                 Telephone No.: (212) 261-7344

                                         Lending Office for Base Rate Advances:
                                         Credit Lyonnais New York Branch
                                         1301 Avenue of the Americas
                                         New York, NY  10019-6022

                                         Lending Office for Eurodollar Advances:
                                         Credit Lyonnais New York Branch
                                         1301 Avenue of the Americas
                                         New York, NY  10019-6022


<PAGE>


                                        FLEET NATIONAL BANK,

                                               as Lender

                                       By: /s/ Walter J. Marullo
                                                   Walter J. Marullo
                                                   Vice President

                                    Address for Notices:

                                    100 Federal Street, MS 01-08-05
                                    P.O. Box 2016
                                    Boston, Massachusetts 02106
                                    Attention: Walter J. Marullo, Vice President

                                          Fax No.: (617) 434-2472
                                          Telephone No.: (617) 434-2308

                                          Lending Office for Base Rate Advances:
                                                     Fleet National Bank
                                                     One Federal Street
                                                     Mail Stop: MA OF D07B
                                                     Boston, MA  02110

                                         Lending Office for Eurodollar Advances:
                                                     Fleet National Bank
                                                     One Federal Street
                                                     Mail Stop:  MA OF D07B
                                                     Boston, MA  02110


<PAGE>


                                 IMPERIAL BANK,

                                    as Lender

                                                     By: /s/ M. Metheany
                                                     Name: M. Metheany
                                                     Title: Vice President

                                                  Address for Notices:
                                                  226 Airport Parkway
                                                  San Jose, California  95110
                                                  Attention: Kelly Davis

                                                  Fax No.: (408) 451-8586
                                                  Telephone No.: (408) 451-8589


                            Lending Office for Base Rate Advances:
                                                     Imperial Bank
                                                     226 Airport Parkway
                                                     San Jose, CA  95110

                            Lending Office for Eurodollar Advances:
                                                     Imperial Bank
                                                     226 Airport Parkway
                                                     San Jose, CA  95110


<PAGE>

                              LASALLE BANK, NATIONAL ASSOCIATION

                                    as Lender

                                                     By: /s/ Dana Friedman
                                                     Name: Dana Friedman
                                                     Title: Lending Officer

                                            Address for Notices:
                                            135 South LaSalle Street
                                            Chicago, Illinois  60603
                                            Attention: Dana Friedman

                                            Fax No.: (312) 904-6457
                                            Telephone No.: (312) 904-6583

                                         Lending Office for Base Rate Advances:
                                         LaSalle Bank, National Association
                                         135 South LaSalle Street
                                         Chicago, IL  60603

                                         Lending Office for Eurodollar Advances:
                                         LaSalle Bank, National Association
                                         135 South LaSalle Street
                                         Chicago, IL  60603



<PAGE>

                                        COOPERATIEVE CENTRALE RAIFFEISEN -
                                        BOERENLEENBANK B.A., "RABOBANK
                                        NEDERLAND", NEW YORK BRANCH,  as Lender



                                                     By: /s/ J. David Thomas
                                                              J. David Thomas
                                                              Vice President

                                                     By: /s/ W. Pieter C. Kodde
                                                              W. Pieter C. Kodde
                                                              Vice President

                                        Address for Notices:
                                        245 Park Avenue
                                        New York, New York  10167
                                        Attention: Corporate Services Department

                                                  Fax. No.: (212) 818-0233
                                                  Telephone No.: (212) 916-7800

                                           cc:     1201 West Peachtree Street,
                                                   Suite 3450
                                                   Atlanta, Georgia 30309-3400
                                                   Attention: Terrell Boyle

                                                   Fax. No.: (404) 877-9150
                                                   Telephone No.: (404) 877-9106

                                      Lending Office for Base Rate Advances:
                                            Cooperatieve Centrale Raiffeisen -
                                            Boerenleenbank B.A., "Rabobank
                                            Nederland", New York Branch
                                            245 Park Avenue
                                            New York, NY  10167

                                        Lending Office for Eurodollar Advances:
                                           Cooperatieve Centrale Raiffeisen -
                                           Boerenleenbank B.A., "Rabobank
                                           Nederland", New York Branch
                                           245 Park Avenue
                                           New York, NY  10167





<PAGE>





GUARANTY FEDERAL BANK, F.S.B.

By: /s/ Chris Harkrider
       Chris Harkrider
       Vice President

Addresses for Notices:

301 Congress Avenue
Suite 300
Austin, TX  78701
Attention:  Chris Harkrider

Fax No.:     (512) 320-1041
Telephone No.:  (512) 320-1205

Lending Office for Base Rate Advances:

Guaranty Federal Bank, F.S.B.
8333 Douglas Avenue
Dallas, TX 75225

Lending Office for Eurodollar Advances:

Guaranty Federal Bank, F.S.B.
8333 Douglas Avenue
Dallas, TX 75225




                                                   Pledge and Security Agreement



                          PLEDGE AND SECURITY AGREEMENT

         THIS  PLEDGE  AND  SECURITY  AGREEMENT  (the  "Agreement")  dated as of
January 31,  2000,  is by and between OHIO LITHO,  INC., a Delaware  corporation
("Pledgor"), whose street address is 1301 Capital of Texas Highway, Suite C-300,
Austin, Texas 78746-6550,  for the benefit of BANK OF AMERICA,  N.A., a national
banking association ("B of A"), whose street address is 901 Main Street, Dallas,
Texas 75202, not in its individual  capacity but solely as administrative  agent
for itself and each of the other banks or lending institutions (each, a "Lender"
and collectively, the "Lender") which is or may from time to time become a party
to the Loan Agreement (as hereinbelow defined) (in such capacity,  together with
its successors in such capacity, the "Administrative Agent").

                                R E C I T A L S:

     A. Prime Medical Services, Inc., a Delaware corporation  ("Borrower"),  has
entered into that certain Fourth Amended and Restated Loan Agreement dated as of
the date hereof with B of A as Administrative Agent and as a Lender, BankBoston,
N.A., as Documentation Agent and as a Lender, and the other Lenders from time to
time party thereto, as amended,  waived, restated, and supplemented from time to
time ("Loan Agreement").

         B. Pledgor and certain  other  guarantors  have  executed  that certain
Guaranty  Agreement  dated as of the date  hereof  (as the same may be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
Pledgor has guaranteed to the Agents (as defined in the Loan  Agreement) and the
Lenders  the full and  complete  payment  and  performance  of the  liabilities,
obligations,  and  indebtedness  of the  Borrower  to the Agents and the Lenders
under the Loan Documents (as defined in the Loan Agreement).

     C. As a condition to entering into the Loan Agreement, Pledgor must execute
and deliver this Agreement.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, Pledgor agrees with the Administrative Agent as follows:

                                    ARTICLE I

                                   DEFINITIONS

         (a) Each term used herein and defined in the Loan Agreement  shall have
the  meaning  assigned to it in the Loan  Agreement,  unless  otherwise  defined
herein or the context otherwise requires.

         (b) In addition,  as used herein,  the  following  terms shall,  unless
otherwise indicated, have the following meanings:

         "Borrower" has the meaning set forth in the recitals.

         "Code" shall mean the Uniform Commercial Code as in effect in the State
of Texas.


<PAGE>



                                                   Pledge and Security Agreement

                                        3



         "Collateral"  shall mean the assets and interests of Pledgor identified
in Section 2.1 hereof.

         "Event of  Default"  shall have the  meaning  assigned  to such term in
Section 5.1.

         "Guaranty" shall mean that certain  Guaranty  Agreement dated as of the
date hereof, executed by Pledgor and certain other guarantors for the benefit of
the Agents and the Lenders, guaranteeing the full payment and performance of the
Obligations, as amended, modified, confirmed, and extended from time to time.

         "Partnerships"  shall mean (a) those partnerships and limited liability
companies  listed on  Exhibit  A  attached  hereto  and  incorporated  herein by
reference,  as such  partnerships  or limited  liability  companies exist or may
hereinafter be restated,  amended or restructured,  (b) any  partnership,  joint
venture,  or limited  liability  company in which  Pledgor  shall,  at any time,
become  a  limited  or  general  partner,   venturer,  or  member,  or  (c)  any
partnership, joint venture or corporation formed as a result of the restructure,
reorganization or amendment of the Partnerships.

         "Partnership  Agreements"  shall  mean (a) those  agreements  listed on
Exhibit B attached hereto and  incorporated  herein by reference  (together with
any  modifications,  amendments or  restatements  thereof),  and (b) partnership
agreements,  joint venture agreements,  or organizational  agreements for any of
the partnerships,  joint ventures,  or limited liability  companies described in
clause  (b) of  the  definition  of  "Partnerships"  above  (together  with  any
modifications,  amendments or restatements thereof), and "Partnership Agreement"
means any one of the Partnership Agreements.

         "Pledged Partnership Interests" shall mean all of Pledgor's partnership
interests,  whether general or limited, venture, or membership interests, in the
Partnerships,  including,  without limitation, all of Pledgor's right, title and
interest now or hereafter accruing under the Partnership Agreements with respect
to any  interest  now owned or  hereafter  acquired  or owned by  Pledgor in the
Partnerships,  and including all  distributions,  allocations,  proceeds,  fees,
preferences,  payments or other benefits,  which Pledgor now is or may hereafter
become  entitled to receive with respect to such  interests in the  Partnerships
and with respect to the repayment of all loans now or hereafter  made by Pledgor
to the Partnerships,  and Pledgor's undivided  percentage interest in the assets
of the Partnerships.

         "Secured  Indebtedness" shall have the meaning assigned to such term in
Section 2.1(c) hereof.

         "Security Interests" shall mean the pledge, collateral assignment,  and
security interests securing the Secured  Indebtedness,  including (i) the pledge
and  security  interest in the  Pledged  Partnership  Interests  granted in this
Agreement  and  (ii)  all  other  security  interests  created  or  assigned  as
additional security for the Secured  Indebtedness  pursuant to the provisions of
this Agreement.

         (c) Whenever the context so requires,  the neuter  gender  includes the
masculine and  feminine,  and the singular  number  includes the plural and vice
versa.


<PAGE>


                                   ARTICLE II

                            COLLATERAL AND OBLIGATION

         SECTION 2.1       Grant of Security Interest.
                           --------------------------

         (a) As collateral  security for Secured  Indebtedness,  Pledgor  hereby
pledges and grants to the Administrative  Agent, for the benefit of the Lenders,
a first  priority  lien on and  security  interest  in and to,  and  agrees  and
acknowledges  that the  Administrative  Agent has, and shall continue to have, a
security interest in and to, and assigns, transfers,  pledges and conveys to the
Administrative  Agent, all of Pledgor's right,  title and interest in and to the
following  described  collateral  (the  "Collateral")  now  owned  or  hereafter
acquired,  wherever  located,  howsoever  arising or  created,  and  whether now
existing or hereafter arising, existing or created:

                    (i)  the  Pledged  Partnership  Interests  and all rights of
                         Pledgor with respect  thereto and all proceeds,  income
                         and profits therefrom;

                  (ii)     all of Pledgor's  distribution rights, income rights,
                           liquidation  interest,   accounts,  contract  rights,
                           general intangibles,  notes, instruments,  drafts and
                           documents   relating  to  the   Pledged   Partnership
                           Interests;

                  (iii)    to the extent attributable to the Pledged Partnership
                           Interests,  all promissory  notes,  notes receivable,
                           accounts,  accounts  receivable and instruments owned
                           or held by Pledgor or, in which Pledgor owns or holds
                           an   interest,    evidencing   obligations   of   the
                           Partnerships;

                  (iv)     all liens, security interests,  collateral,  property
                           and  assets  securing  any of the  promissory  notes,
                           notes receivables,  instruments,  accounts receivable
                           and other  claims and  interest  described  in clause
                           (iii) above;

                    (v)  all books, files, computer records,  computer software,
                         electronic  information  and other  files,  records  or
                         information  relating  to any or all of the  foregoing;
                         and

                  (vi)     all substitutions,  replacements, products, proceeds,
                           income and profits arising from any of the foregoing;
                           including without limitation insurance proceeds.

         (b)  The  Security   Interests  are  granted  and  the   Collateral  is
collaterally  assigned as security only and shall not subject the Administrative
Agent or any holder of the  Secured  Indebtedness  to, or transfer or in any way
affect or modify,  any obligation or liability of Pledgor with respect to any of
the Collateral.

         (c)  The   Collateral   shall   secure   the   following   obligations,
indebtedness,  and liabilities  (whether at stated maturity,  by acceleration or
otherwise)  (all  such   obligations,   indebtedness,   and  liabilities   being
hereinafter sometimes called the "Secured Indebtedness"):

                    (i)  the  Obligations and the  obligations,  liabilities and
                         indebtedness  of Pledgor to the Agents and the  Lenders
                         under the Guaranty;



<PAGE>


                  (ii)     all reasonable costs and expenses, including, without
                           limitation,  all reasonable attorneys' fees and legal
                           expenses, incurred by any of the Agents or any Lender
                           to preserve and maintain the Collateral,  collect the
                           obligations   herein  described,   and  enforce  this
                           Agreement; and

          (iii)all  extensions,  renewals,  and  modifications  of  any  of  the
               foregoing.

     SECTION 2.2 Consent.  To the extent any Partnership  Agreement requires the
consent or agreement of Pledgor to the transfer,  conveyance,  or encumbrance as
security  for the  Secured  Indebtedness  of all or any  portion of the  Pledged
Partnership  Interests,  Pledgor hereby irrevocably consents to (a) the grant of
the security  interest  described in Section 2.1 of this Agreement,  and (b) any
transfer or  conveyance  of the Pledged  Partnership  Interests  pursuant to the
Administrative  Agent's exercise of its rights and remedies under Section 5.4 of
this Agreement or under any other Loan Document.

         SECTION 2.3 Pledgor  Remains  Liable.  Notwithstanding  anything to the
contrary contained herein, (a) Pledgor shall remain liable under the Partnership
Agreements  to the  extent set forth  therein  to perform  all of its duties and
obligations  thereunder  to the same  extent as if this  Agreement  had not been
executed  (b) the  exercise  by the  Administrative  Agent of any of its  rights
hereunder shall not release Pledgor from any of its duties or obligations  under
the contracts and  agreements  included in the  Collateral,  and (c) neither the
Administrative Agent nor any Lender shall have any obligation or liability under
the  Partnership  Agreements  by  reason  of  this  Agreement,   nor  shall  the
Administrative  Agent  or  any  Lender  be  obligated  to  perform  any  of  the
obligations or duties of Pledgor  thereunder or to take any action to collect or
enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         REPRESENTATIONS AND WARRANTIES

         Pledgor hereby represents and warrants to the  Administrative  Agent as
follows:

         (a) Pledgor has good and indefeasible title to the Pledged  Partnership
Interests  and  other  Collateral  free and  clear of any  Lien  except  for the
Security  Interests created by this Agreement and the security interests granted
in  favor  of  Bank of  America,  N.A.,  as  Administrative  Agent  ("Refractive
Administrative  Agent")  under the Loan  Agreement  dated the date  hereof  (the
"Refractive  Loan  Agreement")  among  Prime  Refractive   Management,   L.L.C.,
Refractive  Administrative Agent, BankBoston,  N.A., as documentation agent, and
the lenders from time to time party thereto ("Refractive Lenders"),  and has all
necessary  authority to pledge and collaterally  assign the Pledged  Partnership
Interests and other Collateral as security for the Secured  Obligations and such
assignment  and transfer is not contrary to or in conflict with the  Partnership
Agreements or any other agreement;

         (b) No  financing  statement  or other  instrument  similar  in  effect
covering all or any part of the  Collateral is on file in any recording  office,
except such as may have been filed in favor of the Administrative Agent relating
to this Agreement or those in favor of Refractive Administrative Agent;

     (c) This  Agreement  has been duly executed and delivered by Pledgor and is
the legal and binding  obligation of Pledgor  enforceable in accordance with its
terms;


<PAGE>


         (d) Upon  execution  of this  Agreement  and an  appropriate  financing
statement  by  Pledgor  and the  recording  of the  financing  statement  in the
appropriate office, the Administrative  Agent will have a valid, first and prior
perfected security interest in the Collateral;

         (e) Neither the  execution  and  delivery  of this  Agreement,  nor the
consummation of any of the transactions hereby contemplated, nor compliance with
the terms and provisions hereof, will contravene or materially conflict with (i)
any material  provision of law,  statute or  regulation  to which Pledgor or the
Partnerships  is  subject  or  (ii)  any  judgment,  license,  order  or  permit
applicable to Pledgor or the Partnerships.  No consent, approval,  authorization
or  order of any  court,  governmental  authority,  partner  or  third  party is
required that has not been received or taken (i) for the grant by Pledgor of the
Security  Interests,  (ii) for the  execution,  delivery or  performance of this
Agreement by Pledgor,  (iii) for the  perfection of the Security  Interests,  or
(iv) except for such notices as are required by the Code or the Loan  Agreement,
for  the  exercise  by the  Administrative  Agent  of its  rights  and  remedies
hereunder (provided,  however,  that the purchaser of the Collateral at any sale
thereof  pursuant to Section 5.4 hereof may be required to obtain the consent of
the partners in the  Partnerships  and/or satisfy other  conditions set forth in
the Partnership  Agreements prior to such purchaser's  admission as a partner in
the Partnership);

     (f) The chief  executive  office and principal place of business of Pledgor
is in Austin, Travis County, Texas; and

         (g) To the best  knowledge  and belief of  Pledgor,  Pledgor  has fully
performed each and every one of his obligations and duties under the Partnership
Agreements  on or prior to the date due;  Pledgor has not received any notice of
any  default  in  the  performance  of his  obligations  under  the  Partnership
Agreements or of any situation which could give rise to such an event of default
thereunder.

                                   ARTICLE IV

                               PLEDGOR'S COVENANTS

         Pledgor hereby covenants and agrees with the Administrative  Agent that
until the Secured Indebtedness is paid and performed in full:

     (a)  Pledgor  will  not  cause,  permit  or  consent  to any  amendment  or
modification  to the  Partnership  Agreements  in effect  as of the date  hereof
except as permitted in the Loan Agreement;

         (b)  Pledgor  will  pay and  discharge  promptly  when  due all  taxes,
assessments,  forced contributions,  governmental charges, fines, penalties, and
any other lawful claims, of every  description,  payable by Pledgor with respect
to (or  which,  if not paid  could  result  in an  encumbrance  upon) any of the
Collateral, except as otherwise permitted by the terms of the Loan Agreement. In
the  event  that  Pledgor  should,  for any  reason,  fail to pay and  discharge
promptly any taxes,  assessments,  forced  contributions,  governmental charges,
fines, or penalties when due (subject to the provisions of the Loan  Agreement),
then the Administrative  Agent shall be authorized,  but shall not be obligated,
to pay the same, with full  subrogation to all rights of any Person by reason of
such  payment,  and the  amounts  so paid,  together  with  interest  thereon as
provided herein, shall be secured by the Security Interests;


<PAGE>


         (c) Pledgor will not sell, transfer, mortgage or otherwise encumber any
Collateral  in any  manner,  except  for  the  security  interest  in  favor  of
Refractive  Administrative Agent, without first obtaining the written consent of
the  Administrative  Agent.  Any  written  consent to any such  sale,  mortgage,
transfer or encumbrance  shall not be construed to be a waiver of this provision
in respect of any subsequent proposed sale, mortgage, transfer or encumbrance;

         (d)  Pledgor  will,  at its  expense and in such manner and form as the
Administrative Agent may from time to time reasonably require, execute, deliver,
file  and  record  any  financing   statement,   specific  assignment  or  other
instruments,  certificates  or  papers  and take any  other  action  that may be
necessary or desirable,  or that the Administrative  Agent may from time to time
reasonably  request,  in order to  create,  preserve,  perfect or  validate  any
Security Interest or to enable the Administrative  Agent to exercise and enforce
its rights  hereunder with respect to any of the Collateral.  In the event,  for
any  reason,  that the law of any  jurisdiction  other  than the  State of Texas
becomes or is applicable to the Collateral,  or any part thereof, Pledgor agrees
to execute and deliver all such instruments and to do all such other things that
may be necessary or  appropriate  to preserve,  protect and enforce the Security
Interests of the Administrative  Agent under the law of such other jurisdiction,
to at least the same extent that the Security Interests would be protected under
the Code. To the extent permitted by applicable law,  Pledgor hereby  authorizes
the  Administrative  Agent  to  execute  and  file,  in the name of  Pledgor  or
otherwise,  Uniform Commercial Code financing statements that the Administrative
Agent in its sole  discretion  may deem  necessary  or  appropriate  to  further
perfect the Security Interests;

         (e) If Pledgor receives,  by virtue of being or having been an owner of
any of the Collateral, any notes, other instruments, options, cash distributions
or any other distribution,  resulting from a Capital Event (hereinafter defined)
Pledgor  shall  receive the same in trust for the benefit of the  Administrative
Agent,  shall immediately  notify the  Administrative  Agent of such receipt and
shall  immediately  take all such actions and execute all such  documents as the
Administrative  Agent deems  necessary or  appropriate  to continue or create as
first and prior perfected Liens, in favor of the  Administrative  Agent covering
such notes, other instruments,  options, cash distributions. As used herein, the
term  "Capital  Event" shall mean any event  generating or resulting in revenues
not attributable to the normal business operations of the Partnerships including
without   limitation,   any  mortgaging  of  assets,   refinancing  of  existing
indebtedness of any Partnership,  condemnation of any assets of any Partnership,
sale or transfer of any assets of any Partnership outside the ordinary course of
business,  or payment of insurance proceeds.  At all times other than during the
continuance  of an Event of Default,  Pledgor  shall be entitled to receive free
from the security  interest  hereof any note,  other  instrument,  option,  cash
distribution  or any other  distribution  resulting  from any event other than a
Capital Event;

         (f) Pledgor will notify the  Administrative  Agent in writing  prior to
the removal of Pledgor's chief  executive  office or principal place of business
from the State of Texas;

         (g) Pledgor shall cause to be obtained any and all waivers and consents
necessary to make  effective the grant  contained in and to perfect the security
interest  granted to the  Administrative  Agent  pursuant to Section 2.1 hereof,
including without limitation,  all necessary waivers and consents from the other
partners, if any, of each Partnership;

         (h) Pledgor shall perform fully all obligations  imposed upon it by any
agreements  or  instruments  concerning  all or  any  part  of  the  Collateral,
including  without  limitation the Partnership  Agreements and shall maintain in
full force and effect all such agreements and  instruments,  and shall not amend
or modify,  or consent to the amendment or  modification  of such  agreements or
instruments, without the prior written consent of the Administrative Agent; and


<PAGE>


         (i)  Pledgor  shall  promptly  notify the  Administrative  Agent of any
material adverse change in any material fact or material circumstance  warranted
or represented by Pledgor in this Agreement or in any other writing furnished by
Pledgor to the  Administrative  Agent in connection  with the  Collateral or the
Secured Indebtedness,  and shall promptly notify the Administrative Agent of any
claim,  action or  proceeding  affecting  title to the  Collateral,  or any part
thereof,  or  the  Security  Interests  herein,  and,  at  the  request  of  the
Administrative  Agent, shall appear and defend, at Pledgor's  expense,  any such
action or proceeding.

                                    ARTICLE V

                    GENERAL AUTHORITY AND POWERS AND REMEDIES

         SECTION 5.1       Events of Default.
                           -----------------

         Pledgor shall be in default under this  Agreement upon the happening of
any of the  following  events  or  conditions  (hereinafter  called an "Event of
Default"):

         (a)      An Event of Default under the Loan Agreement shall occur; or

     (b) The ownership of any of the  Collateral  becomes  vested in a person or
entity other than Pledgor, except as permitted hereunder; or

     (c) The Administrative Agent's Liens in any of the Collateral should become
unenforceable, or cease to be first priority Liens.

         SECTION 5.2 Right to Receive  Distributions.  The Administrative  Agent
shall  have the  right,  at any time  following  the  occurrence  and during the
continuation of an Event of Default,  to receive all payments and  distributions
made to Pledgor upon or with  respect to the  Collateral  and Pledgor  agrees to
take all such action as the  Administrative  Agent may reasonably deem necessary
or appropriate to give effect to such right.

         SECTION 5.3 General Authority.  Pledgor hereby irrevocably appoints the
Administrative  Agent,  and its  successors  and  assigns,  the true and  lawful
attorney-in-fact  of Pledgor,  with full power of  substitution,  in the name of
Pledgor,  for the sole  use and  benefit  of the  Administrative  Agent,  but at
Pledgor's expense,  to the extent permitted by law to exercise,  at any time and
from time to time  following the  occurrence  and during the  continuance  of an
Event of Default,  all or any of the following powers with respect to all or any
of the Collateral:

     (a) to ask,  demand,  sue for,  collect,  receive and give  acquittance and
receipts for any and all monies due or to become due upon or by virtue thereof;

     (b) to  receive,  endorse,  and  collect  any drafts or other  instruments,
documents and chattel paper,
in connection with clause (a) preceding;

     (c) to  settle,  compromise,  compound,  prosecute  or defend any action or
proceeding with respect thereto;



<PAGE>


         (d)  subject  to  Section  5.4  hereof,  to sell,  transfer,  assign or
otherwise  deal in or with  the  same  or the  proceeds  thereof  as  fully  and
effectually as if the Administrative Agent were the absolute owner thereof; and

     (e) to extend  the time of payment  of any or all  thereof  and to make any
allowance and other adjustments with reference thereto.

In addition,  the  Administrative  Agent, at any time, either before or after an
Event of Default, shall have the right, together with such accountants and other
agents or representatives as they may from time to time designate,  to visit and
inspect the Partnerships'  properties,  assets, books, records and documents and
to discuss the Partnerships'  affairs,  finances and accounts with Pledgor's and
the Partnerships'  representatives,  officers or directors,  during all business
hours as the  Administrative  Agent  may  designate,  and to make and take  away
copies of the  Partnerships'  records  at the  Administrative  Agent's  expense.
Pledgor  shall  furnish  to  Administrative  Agent  any  information  reasonably
requested by the Administrative Agent in connection with the Collateral. Pledgor
will maintain complete and accurate books and records regarding the Collateral.

         SECTION 5.4       Remedies Upon Default.
                           ---------------------

         (a) If any Event of Default shall have occurred and is continuing,  the
Administrative  Agent,  at its option,  without demand,  presentment,  notice of
acceleration,  intention to  accelerate or other notice (which are fully waived)
may:

                  (1) exercise all the rights of a secured  party under the Code
         (whether  or not the Code is in effect in the  jurisdiction  where such
         rights are exercise, unless prohibited by applicable law).

               (2) apply the cash, if any, then held by the Administrative Agent
          as Collateral as specified in Section 5.6.

                  (3) sell all of the  Collateral  or any part thereof at public
         or private sale or at any broker's board or on any securities exchange,
         for cash,  upon  credit or for  future  delivery,  and at such price or
         prices as the  Administrative  Agent may reasonably deem  satisfactory.
         Upon the  Administrative  Agent's  demand,  Pledgor will take all steps
         necessary to prepare the  Collateral  for and  otherwise  assist in any
         proposed  disposition  of the  Collateral.  Any  holder of the  Secured
         Indebtedness  may be the  purchaser of any or all of the  Collateral so
         sold at any public sale (or, if the Collateral is of a type customarily
         sold in a  recognized  market or is of a type  which is the  subject of
         widely distributed standard price quotations,  at any private sale) and
         thereafter  hold the same  absolutely,  free from any right or claim of
         whatsoever kind. Any holder of the Secured  Indebtedness shall have the
         right to offset  the amount of its bid  against an equal  amount of the
         Secured Indebtedness held by such holder.


<PAGE>


         Pledgor agrees that, because of the Securities Act of 1933, as amended,
         or any other laws or regulations,  and for other reasons,  there may be
         legal  and/or  practical  restrictions  or  limitations  affecting  the
         Administrative  Agent in any attempts to dispose of certain portions of
         the  Collateral  and for the  enforcement  of their  rights.  For these
         reasons,  the Administrative Agent is hereby authorized by Pledgor, but
         not obligated,  upon the occurrence and during the  continuation  of an
         Event of Default,  to sell all or any part of the Collateral at private
         sale,  subject to  investment  letter or in any other manner which will
         not require the  Collateral,  or any part thereof,  to be registered in
         accordance  with the Securities  Act of 1933, as amended,  or the rules
         and  regulations   promulgated   thereunder,   or  any  other  laws  or
         regulations,  at a  reasonable  price  at such  private  sale or  other
         distribution in the manner  mentioned above.  Pledgor  understands that
         the  Administrative  Agent  may in its  discretion  approach  a limited
         number of potential purchasers and that a sale under such circumstances
         may  yield a lower  price  for the  Collateral,  or any  part or  party
         thereof,  than would  otherwise be obtainable if such  collateral  were
         either  afforded  to  a  larger  number  or  potential  purchasers,  or
         registered or sold in the open market. Pledgor agrees that such private
         sale  shall be deemed to have  been made in a  commercially  reasonable
         manner,  and that the  Administrative  Agent has no obligation to delay
         sale of any  Collateral to permit the issuer thereof to register it for
         public sale under any applicable federal or state securities laws.

         The  Administrative  Agent is authorized,  in connection  with any such
         sale (i) to restrict the prospective bidders on or purchasers of any of
         the Collateral to a limited number of sophisticated  investors who will
         represent and agree that they are  purchasing for their own account for
         investment  and not with a view to the  distribution  or sale of any of
         such Collateral and (ii) to impose such other limitations or conditions
         in connection with any such sale as the Administrative Agent reasonably
         deems  necessary  in order  to  comply  with  applicable  law.  Pledgor
         covenants  and agrees that it will execute and deliver  such  documents
         and take such other action as the Administrative Agent reasonably deems
         necessary  in order that any such sale may be made in  compliance  with
         applicable law. Upon any such sale the Administrative  Agent shall have
         the right to deliver,  assign and transfer to the purchaser thereof the
         Collateral  so sold.  Each  purchaser  at any such sale  shall hold the
         Collateral so sold absolutely,  free from any claim or right of Pledgor
         of  whatsoever  kind,  including  any equity or right of  redemption of
         Pledgor.  Pledgor,  to the extent  permitted by applicable  law, hereby
         specifically  waives all rights of redemption,  stay or appraisal which
         it has or may have under any law now existing or hereafter enacted.

         Pledgor   agrees   that  five  (5)  days'   written   notice  from  the
         Administrative Agent to Pledgor of the Administrative Agent's intention
         to make any such public or private sale or sale at a broker's  board or
         on a securities  exchange shall  constitute  "reasonable  notification"
         within the meaning of Section  9-504(c) of the Code.  Such notice shall
         (1) in case of a public  sale,  state the time and place fixed for such
         sale,  (2) in  case  of sale at a  broker's  board  or on a  securities
         exchange,  state the board or  exchange  at which  such a sale is to be
         made and the day on which the  Collateral,  or the  portion  thereof so
         being sold, will first be offered to sale at such board or exchange and
         (3) in the case of a private sale,  state the day after which such sale
         may be consummated.  Any such public sale shall be held at such time or
         times within ordinary business hours and at such place or places as the
         Administrative  Agent may fix in the notice of such  sale.  At any such
         sale,  the  Collateral  may be  sold in one  lot as an  entirety  or in
         separate parcels, as the Administrative Agent may reasonably determine.
         The  Administrative  Agent shall not be obligated to make any such sale
         pursuant to any such  notice.  The  Administrative  Agent may,  without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place  fixed  for the  sale,  and such  sale may be made at any time or
         place to which the same may be so adjourned.


<PAGE>


         In case of any sale of all or any part of the  Collateral  on credit or
         for future  delivery,  the  Collateral  so sold may be  retained by the
         Administrative  Agent until the selling  price is paid by the purchaser
         thereof,  but the Administrative Agent shall not incur any liability in
         case  of the  failure  of  such  purchaser  to  take up and pay for the
         Collateral so sold and in case of any such failure, such Collateral may
         again be sold upon like notice.  The Administrative  Agent,  instead of
         exercising the power of sale herein conferred upon it, may proceed by a
         suit or suits at law or in equity to foreclose  the Security  Interests
         and sell the Collateral,  or any portion  thereof,  under a judgment or
         decree of a court or courts of competent jurisdiction.

         (b)  Without  the  limiting  the   foregoing,   or  imposing  upon  the
Administrative  Agent any  obligations or duties not required by applicable law,
Pledgor acknowledges and agrees that, in foreclosing upon any of the Collateral,
or exercising  any other rights or remedies  provided the  Administrative  Agent
hereunder or under applicable law, the  Administrative  Agent may, but shall not
be required to (1) qualify or restrict prospective  purchasers of the Collateral
by requiring evidence of sophistication and/or  creditworthiness,  and requiring
the execution and delivery of confidentiality  agreements or other documents and
agreements as a condition to such prospective purchasers' receipt of information
regarding the Collateral or participation  in any public or private  foreclosure
sale process; (2) provide to prospective  purchasers the Partnership  Agreements
and business and financial information  regarding the Partnerships  available in
the files of the Administrative  Agent at the time of commencing the foreclosure
process,  without the requirement that the Administrative  Agent obtain, or seek
to  obtain,  any  updated  business  or  financial  information  or  Partnership
Agreements, or verify, or certify to prospective purchasers, the accuracy of any
such business or financial  information or Partnership  Agreements;  (3) sell at
foreclosure  all, or a portion but not all, of the rights,  titles and interests
of  Pledgor  in a  particular  Partnership  or group of  Partnerships;  it being
further  specifically  acknowledged  by Pledgor  that  limitations  or potential
limitations  on  the  transfer  of  certain  Collateral  under  the  Partnership
Agreements or other  applicable  agreements or law may limit the  Administrative
Agent's right or ability to foreclose  upon or sell certain  rights,  titles and
interests  of  Pledgor  in the  Partnerships;  (4)  offer  for  sale,  and sell,
partnership  interests  either with, or without,  first  employing an appraiser,
investment  banker, or broker with respect to the evaluation of Collateral,  the
solicitation of purchasers for Collateral, or the manner of sale of Collateral.

         (c) The  Administrative  Agent  shall  have all  rights,  remedies  and
recourse  granted in the Loan Agreement and the other Loan Documents or existing
at common law or equity (including  specifically those granted by the Code), and
such rights and  remedies (1) shall be  cumulative  and  concurrent,  (2) may be
pursued separately,  successively or concurrently  against Pledgor and any party
obligated to pay or perform the Obligations, any of the Collateral, or any other
security  for  any  of  the   Obligations,   at  the  sole   discretion  of  the
Administrative  Agent,  and (3) may be exercised  as often as occasion  therefor
shall arise, it being agreed by Pledgor that the exercise or failure to exercise
any such  rights  or  remedies  shall in no event be  construed  as a waiver  or
release thereof or of any other right, remedy or recourse.

         (d)  Notwithstanding  a  foreclosure  upon  any  of the  Collateral  or
exercise of any other remedy by the  Administrative  Agent in connection with an
Event of Default,  Pledgor shall not be subrogated  thereby to any rights of the
Administrative Agent against the Collateral or any other security for any of the
Obligations.  Pledgor shall not be deemed to be the owner of any interest in any
of  the  Obligations  until  all  of  the  Obligations  have  been  paid  to the
Administrative Agent and are fully performed and discharged.

         (e)  All  recitals  in  any  instrument  of  assignment  or  any  other
instrument executed by the Administrative  Agent incident to the sale, transfer,
assignment or other  disposition  or  utilization  of the Collateral or any part
thereof  hereunder  shall be presumptive  evidence of the matters stated therein
and all  prerequisites  of such sale or other action  contained in such recitals
shall be presumed to have been performed or to have occurred.


<PAGE>


         SECTION  5.5  Waivers  by  Pledgor.  In case of any  Event of  Default,
neither Pledgor nor anyone claiming by, through or under Pledgor,  to the extent
Pledgor  may  lawfully  so  agree,  shall or will set up,  claim or seek to take
advantage of any appraisement,  valuation, stay, extension or redemption law now
or hereafter in force in any locality  where any of the  Collateral  is situated
for purposes of applicable law, in order to prevent or hinder the enforcement of
this  Agreement,  or the  absolute  sale of the  Collateral,  or the  final  and
absolute putting into possession  thereof,  immediately  after such sale, of the
purchaser thereof;  and Pledgor in Pledgor's own right and for all who may claim
under Pledgor, hereby waives, to the fullest extent that Pledgor may lawfully do
so, the benefit of any and all right to have the  Collateral  marshaled upon any
enforcement of the Security  Interests  herein granted,  and Pledgor agrees that
the  Administrative  Agent or any  court  having  jurisdiction  to  enforce  the
Security Interests may sell the Collateral in parts or as an entirety.

         SECTION 5.6  Application of Proceeds.  The  Administrative  Agent shall
apply  the  proceeds  of any  foreclosure  sale or  other  realization  upon the
Collateral  as follows  (as  modified,  if  necessary,  by the  requirements  of
applicable law):

         (a) First,  to the payment of all reasonable  costs and expenses of any
foreclosure   and  collection   hereunder  and  all  proceedings  in  connection
therewith, including reasonable compensation to Administrative Agent's counsel;

         (b) Then,  to the  reimbursement  of the  Administrative  Agent for all
disbursements made by the Administrative  Agent for taxes,  assessments or liens
superior to the Security Interests and which the Administrative Agent shall deem
expedient to pay;

     (c) Then, to the  reimbursement of the  Administrative  Agent for any other
disbursements  made by, or reasonable  expenses incurred by, the  Administrative
Agent in accordance with the terms hereof;

     (d) Then,  to the Secured  Indebtedness,  in any manner  determined  by the
Administrative Agent in its sole discretion;

     (e)  Then,  to  the  Refractive  Administrative  Agent  until  all  secured
obligations of Pledgor to it and Refractive Lenders have been paid; and

     (f)      The remainder of such proceeds, if any, shall be paid to Pledgor.

         The foregoing  application  provisions shall apply not only to proceeds
resulting from foreclosure but also to proceeds or distributions  resulting from
any other claim,  (including claims made in bankruptcy  proceedings),  action or
proceeding  to  enforce  or  protect  the  Administrative  Agent's  lien  in the
Collateral.

         SECTION  5.7  Enforcement  of  Secured  Indebtedness.  Nothing  in this
Agreement  shall affect or impair the  unconditional  and absolute  right of the
Administrative  Agent to enforce the Secured  Indebtedness  as and when the same
shall become due in accordance  with the terms of the Loan Documents  whether by
acceleration or otherwise.


<PAGE>



                                   ARTICLE VI

                                  MISCELLANEOUS

         SECTION 6.1 Terms Commercially Reasonable.  The terms of this Agreement
shall be deemed  commercially  reasonable  within  the  meaning  of the  Uniform
Commercial Code in effect and applicable hereto.

         SECTION 6.2 Headings.  The headings of articles and sections herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope or intent of any provision of this Agreement.

         SECTION   6.3   Amendments.   No   change,   amendment,   modification,
cancellation  or discharge of any  provision  of this  Agreement  shall be valid
unless consented to in writing by the Administrative  Agent and Pledgor (subject
to the terms of the Loan Agreement).

         SECTION  6.4  Assignment  of the  Administrative  Agent's  Rights.  The
Administrative  Agent  shall have the right to assign all or any  portion of its
rights  under  this  Agreement  to  any  subsequent  holder  or  holders  of the
Obligations.

         SECTION  6.5 Parties in  Interest.  As and when used  herein,  the term
"Pledgor"  shall mean and include  Pledgor  herein named and his  successors and
permitted assigns,  and the term  "Administrative  Agent" shall mean and include
the  Administrative  Agent herein named and his successors and assigns,  and all
covenants and  agreements  herein shall be binding upon and inure to the benefit
of Pledgor and the Administrative  Agent and their respective assigns,  provided
that  Pledgor  shall have no right to assign his rights  hereunder  to any other
Person  except  in  connection  with  a  transfer  of the  Collateral  permitted
hereunder.

         SECTION  6.6  APPLICABLE  LAWS.  THIS  AGREEMENT  SHALL  BE  CONSTRUED,
INTERPRETED  AND  ENFORCED  UNDER AND PURSUANT TO THE LAWS OF THE STATE OF TEXAS
AND  APPLICABLE  FEDERAL LAW. IF ANY  PROVISION OF THIS  AGREEMENT IS HELD TO BE
INVALID  OR  UNENFORCEABLE,   THE  VALIDITY  AND  ENFORCEABILITY  OF  THE  OTHER
PROVISIONS OF THIS AGREEMENT SHALL REMAIN UNAFFECTED.

         SECTION 6.7 Notices.  Any notices or other  communications  required or
permitted to be given by this Agreement or any other  documents and  instruments
referred  to herein  must be given in  accordance  with  Section  11 of the Loan
Agreement, to the address of such party as follows:

   If to the Administrative Agent:
                                  515 Congress Avenue, 11th Floor
                                  Austin, Texas 78701
                                  Attn: Wade Morgan

                    If to Pledgor:
                                  1301 Capital of Texas Highway
                                  Suite C-300
                                  Austin, Texas 78746-6550
                                  Attn: Treasurer


<PAGE>


         SECTION 6.8  Financing  Statement.  The  Administrative  Agent shall be
entitled  at any  time to file a  photographic  or  other  reproduction  of this
Agreement as a financing statement,  but the failure of the Administrative Agent
to do so shall not impair the validity or enforceability of this Agreement.

         SECTION  6.9  Obligations  Absolute.  All  rights and  remedies  of the
Administrative  Agent hereunder,  and all obligations of the Pledgor  hereunder,
shall be absolute and unconditional irrespective of:

          (a) any lack of validity or  enforceability  of the Loan  Agreement or
     any of the other  Loan  Documents  or any  other  agreement  or  instrument
     relating to any of the foregoing;

          (b) any change in the time,  manner, or place of payment of, or in any
     other term of, all or any of the  Obligations,  or any other  amendment  or
     waiver of or any consent to any departure from the Loan Agreement or any of
     the other Loan Documents;

          (c) any exchange,  release, or nonperfection of any Collateral, or any
     release or  amendment  or waiver of or consent  to any  departure  from any
     guarantee, for all or any of the Obligations; or

                  (d) any other circumstance  (other than payment in full of the
         Obligations) that might otherwise constitute a defense available to, or
         a discharge of, Pledgor.

         SECTION 6.10  Confirmation  of Liens.  Pledgor  acknowledges  that this
Agreement has been given in amendment, renewal, restatement, and confirmation of
Pledgor's  obligations,  covenants,  and agreements  contained in the Pledge and
Security  Agreements  previously  executed by Pledgor in favor of Administrative
Agent and the Lenders, including,  without limitation, that dated April 26, 1996
(the "Previous  Pledge").  Pledgor further  confirms and agrees that neither the
execution of the Loan Agreement or any other Loan Document,  or the consummation
of the transactions described therein, shall in any way affect the liens granted
under the  Previous  Pledge  or the  perfection  or  priority  thereof,  and the
obligations  evidenced by the Previous  Pledge shall  continue in full force and
effect as modified, amended and restated by the terms contained herein.

         SECTION 6.11  Counterparts.  This Agreement may be executed in multiple
counterparts,  each of which shall be deemed to be an original, but all of which
shall  constitute  one and the  same  instrument,  and in  making  proof of this
Agreement it shall not be necessary to produce or account for more than one such
counterpart.


<PAGE>


         SECTION  6.12 ENTIRE  AGREEMENT.  THIS  AGREEMENT  EMBODIES  THE FINAL,
ENTIRE  AGREEMENT  OF  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  WITH  RESPECT TO
PLEDGOR'S PLEDGE OF THE PLEDGED  PARTNERSHIP  INTERESTS AND RESTATES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN OR ORAL,  RELATING TO THE  SUBJECT  MATTER  HEREOF.  THIS  AGREEMENT  IS
INTENDED  BY  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  AS A FINAL  AND  COMPLETE
EXPRESSION  OF THE TERMS OF THIS  AGREEMENT,  AND NO COURSE OF  DEALING  BETWEEN
PLEDGOR,  THE  AGENTS  OR THE  LENDERS,  NO  COURSE  OF  PERFORMANCE,  NO  TRADE
PRACTICES,  AND  NO  EVIDENCE  OF  PRIOR,  CONTEMPORANEOUS  OR  SUBSEQUENT  ORAL
AGREEMENTS OR  DISCUSSIONS  OR OTHER  EXTRINSIC  EVIDENCE OF ANY NATURE SHALL BE
USED TO CONTRADICT, VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS AGREEMENT. THERE
ARE NO ORAL AGREEMENTS AMONG PLEDGOR, THE AGENTS AND THE LENDERS.

                     [REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGES FOLLOW.]


<PAGE>



                                                   Pledge and Security Agreement

         IN WITNESS  WHEREOF,  Pledgor has executed this Agreement as of the day
and year first above written.

                                    PLEDGOR:

                                                     OHIO LITHO, INC.,
                                                       a Delaware corporation

                                                     By: /s/ Teena E. Belcik
                                                              Teena E. Belcik
                                                              Treasurer


<PAGE>



                                                                       Exhibit A



                                    EXHIBIT A

                                  PARTNERSHIPS

Ohio Mobile Lithotripter, Ltd.

Ohio Mobile Lithotripter II, Ltd.





<PAGE>



                                                                       Exhibit B



                                    EXHIBIT B

                             PARTNERSHIP AGREEMENTS

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter,  Ltd. dated August 1, 1991, as amended by First Amendment to First
Amended and Restated  Agreement of Limited  Partnership dated as of December 31,
1992

Certificate of Limited Partnership of Ohio Mobile  Lithotripter,  Ltd. dated May
21, 1991

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter II, Ltd.

Certificate of Limited  Partnership of Ohio Mobile  Lithotripter  II, Ltd. dated
August 23, 1995




                          Pledge and Security Agreement



                          PLEDGE AND SECURITY AGREEMENT

         THIS  PLEDGE  AND  SECURITY  AGREEMENT  (the  "Agreement")  dated as of
January 31,  2000,  is by and between OHIO LITHO,  INC., a Delaware  corporation
("Pledgor"), whose street address is 1301 Capital of Texas Highway, Suite C-300,
Austin, Texas 78746-6550,  for the benefit of BANK OF AMERICA,  N.A., a national
banking association ("B of A"), whose street address is 901 Main Street, Dallas,
Texas 75202, not in its individual  capacity but solely as administrative  agent
for itself and each of the other banks or lending institutions (each, a "Lender"
and collectively, the "Lender") which is or may from time to time become a party
to the Loan Agreement (as hereinbelow defined) (in such capacity,  together with
its successors in such capacity, the "Administrative Agent").

                                R E C I T A L S:

     A.  Prime  Refractive  Management,  L.L.C.,  a Delaware  limited  liability
company  ("Borrower"),  has entered into that certain Loan Agreement dated as of
the date hereof with B of A as Administrative Agent and as a Lender, BankBoston,
N.A., as Documentation Agent and as a Lender, and the other Lenders from time to
time party thereto, as amended,  waived, restated, and supplemented from time to
time ("Loan Agreement").

         B. Pledgor and certain  other  guarantors  have  executed  that certain
Guaranty  Agreement  dated as of the date  hereof  (as the same may be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
Pledgor has guaranteed to the Agents (as defined in the Loan  Agreement) and the
Lenders  the full and  complete  payment  and  performance  of the  liabilities,
obligations,  and  indebtedness  of the  Borrower  to the Agents and the Lenders
under the Loan Documents (as defined in the Loan Agreement).

     C. As a condition to entering into the Loan Agreement, Pledgor must execute
and deliver this Agreement.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, Pledgor agrees with the Administrative Agent as follows:

                                    ARTICLE I

                                   DEFINITIONS

         (a) Each term used herein and defined in the Loan Agreement  shall have
the  meaning  assigned to it in the Loan  Agreement,  unless  otherwise  defined
herein or the context otherwise requires.

         (b) In addition,  as used herein,  the  following  terms shall,  unless
otherwise indicated, have the following meanings:

         "Borrower" has the meaning set forth in the recitals.

         "Code" shall mean the Uniform Commercial Code as in effect in the State
of Texas.

         "Collateral"  shall mean the assets and interests of Pledgor identified
in Section 2.1 hereof.


<PAGE>



                          Pledge and Security Agreement

                                       12



         "Event of  Default"  shall have the  meaning  assigned  to such term in
Section 5.1.

         "Guaranty" shall mean that certain  Guaranty  Agreement dated as of the
date hereof, executed by Pledgor and certain other guarantors for the benefit of
the Agents and the Lenders, guaranteeing the full payment and performance of the
Obligations, as amended, modified, confirmed, and extended from time to time.

         "Partnerships"  shall mean (a) those partnerships and limited liability
companies  listed on  Exhibit  A  attached  hereto  and  incorporated  herein by
reference,  as such  partnerships  or limited  liability  companies exist or may
hereinafter be restated,  amended or restructured,  (b) any  partnership,  joint
venture,  or limited  liability  company in which  Pledgor  shall,  at any time,
become  a  limited  or  general  partner,   venturer,  or  member,  or  (c)  any
partnership, joint venture or corporation formed as a result of the restructure,
reorganization or amendment of the Partnerships.

         "Partnership  Agreements"  shall  mean (a) those  agreements  listed on
Exhibit B attached hereto and  incorporated  herein by reference  (together with
any  modifications,  amendments or  restatements  thereof),  and (b) partnership
agreements,  joint venture agreements,  or organizational  agreements for any of
the partnerships,  joint ventures,  or limited liability  companies described in
clause  (b) of  the  definition  of  "Partnerships"  above  (together  with  any
modifications,  amendments or restatements thereof), and "Partnership Agreement"
means any one of the Partnership Agreements.

         "Pledged Partnership Interests" shall mean all of Pledgor's partnership
interests,  whether general or limited, venture, or membership interests, in the
Partnerships,  including,  without limitation, all of Pledgor's right, title and
interest now or hereafter accruing under the Partnership Agreements with respect
to any  interest  now owned or  hereafter  acquired  or owned by  Pledgor in the
Partnerships,  and including all  distributions,  allocations,  proceeds,  fees,
preferences,  payments or other benefits,  which Pledgor now is or may hereafter
become  entitled to receive with respect to such  interests in the  Partnerships
and with respect to the repayment of all loans now or hereafter  made by Pledgor
to the Partnerships,  and Pledgor's undivided  percentage interest in the assets
of the Partnerships.

         "Secured  Indebtedness" shall have the meaning assigned to such term in
Section 2.1(c) hereof.

         "Security Interests" shall mean the pledge, collateral assignment,  and
security interests securing the Secured  Indebtedness,  including (i) the pledge
and  security  interest in the  Pledged  Partnership  Interests  granted in this
Agreement  and  (ii)  all  other  security  interests  created  or  assigned  as
additional security for the Secured  Indebtedness  pursuant to the provisions of
this Agreement.

         (c) Whenever the context so requires,  the neuter  gender  includes the
masculine and  feminine,  and the singular  number  includes the plural and vice
versa.


<PAGE>


                                   ARTICLE II

                            COLLATERAL AND OBLIGATION

         SECTION 2.1       Grant of Security Interest.
                           --------------------------

         (a) As collateral  security for Secured  Indebtedness,  Pledgor  hereby
pledges and grants to the Administrative  Agent, for the benefit of the Lenders,
a lien on and security  interest in and to, and agrees and acknowledges that the
Administrative Agent has, and shall continue to have, a security interest in and
to, and assigns, transfers, pledges and conveys to the Administrative Agent, all
of  Pledgor's  right,  title  and  interest  in and to the  following  described
collateral (the "Collateral") now owned or hereafter acquired, wherever located,
howsoever  arising or created,  and whether now existing or  hereafter  arising,
existing or created,  subject to a first lien in favor of Bank of America, N.A.,
as Administrative Agent ("Prime  Administrative Agent") under the Fourth Amended
and Restated Loan Agreement  dated the date hereof (the "Prime Loan  Agreement")
among Prime Medical  Services,  Inc., Prime  Administrative  Agent,  BankBoston,
N.A., as  documentation  agent,  and the lenders ("Prime  Lenders") from time to
time thereunder:

                    (i)  the  Pledged  Partnership  Interests  and all rights of
                         Pledgor with respect  thereto and all proceeds,  income
                         and profits therefrom;


                  (ii)     all of Pledgor's  distribution rights, income rights,
                           liquidation  interest,   accounts,  contract  rights,
                           general intangibles,  notes, instruments,  drafts and
                           documents   relating  to  the   Pledged   Partnership
                           Interests;

                  (iii)    to the extent attributable to the Pledged Partnership
                           Interests,  all promissory  notes,  notes receivable,
                           accounts,  accounts  receivable and instruments owned
                           or held by Pledgor or, in which Pledgor owns or holds
                           an   interest,    evidencing   obligations   of   the
                           Partnerships;

                  (iv)     all liens, security interests,  collateral,  property
                           and  assets  securing  any of the  promissory  notes,
                           notes receivables,  instruments,  accounts receivable
                           and other  claims and  interest  described  in clause
                           (iii) above;

                    (v)  all books, files, computer records,  computer software,
                         electronic  information  and other  files,  records  or
                         information  relating  to any or all of the  foregoing;
                         and

                  (vi)     all substitutions,  replacements, products, proceeds,
                           income and profits arising from any of the foregoing;
                           including without limitation insurance proceeds.

         (b)  The  Security   Interests  are  granted  and  the   Collateral  is
collaterally  assigned as security only and shall not subject the Administrative
Agent or any holder of the  Secured  Indebtedness  to, or transfer or in any way
affect or modify,  any obligation or liability of Pledgor with respect to any of
the Collateral.

         (c)  The   Collateral   shall   secure   the   following   obligations,
indebtedness,  and liabilities  (whether at stated maturity,  by acceleration or
otherwise)  (all  such   obligations,   indebtedness,   and  liabilities   being
hereinafter sometimes called the "Secured Indebtedness"):


<PAGE>


                    (i)  the  Obligations and the  obligations,  liabilities and
                         indebtedness  of Pledgor to the Agents and the  Lenders
                         under the Guaranty;

                  (ii)     all reasonable costs and expenses, including, without
                           limitation,  all reasonable attorneys' fees and legal
                           expenses, incurred by any of the Agents or any Lender
                           to preserve and maintain the Collateral,  collect the
                           obligations   herein  described,   and  enforce  this
                           Agreement; and

                    (iii)all extensions,  renewals,  and modifications of any of
                         the foregoing.

         SECTION 2.2 Consent.  To the extent any Partnership  Agreement requires
the consent or agreement of Pledgor to the transfer,  conveyance, or encumbrance
as security  for the Secured  Indebtedness  of all or any portion of the Pledged
Partnership  Interests,  Pledgor hereby irrevocably consents to (a) the grant of
the security  interest  described in Section 2.1 of this Agreement,  and (b) any
transfer or  conveyance  of the Pledged  Partnership  Interests  pursuant to the
Administrative  Agent's exercise of its rights and remedies under Section 5.4 of
this Agreement or under any other Loan Document.

         SECTION 2.3 Pledgor  Remains  Liable.  Notwithstanding  anything to the
contrary contained herein, (a) Pledgor shall remain liable under the Partnership
Agreements  to the  extent set forth  therein  to perform  all of its duties and
obligations  thereunder  to the same  extent as if this  Agreement  had not been
executed  (b) the  exercise  by the  Administrative  Agent of any of its  rights
hereunder shall not release Pledgor from any of its duties or obligations  under
the contracts and  agreements  included in the  Collateral,  and (c) neither the
Administrative Agent nor any Lender shall have any obligation or liability under
the  Partnership  Agreements  by  reason  of  this  Agreement,   nor  shall  the
Administrative  Agent  or  any  Lender  be  obligated  to  perform  any  of  the
obligations or duties of Pledgor  thereunder or to take any action to collect or
enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         REPRESENTATIONS AND WARRANTIES

         Pledgor hereby represents and warrants to the  Administrative  Agent as
follows:

         (a) Pledgor has good and indefeasible title to the Pledged  Partnership
Interests  and  other  Collateral  free and  clear of any  Lien  except  for the
Security  Interests created by this Agreement and the security interests granted
in favor of Prime  Administrative  Agent,  and has all  necessary  authority  to
pledge and  collaterally  assign the  Pledged  Partnership  Interests  and other
Collateral  as security  for the Secured  Obligations  and such  assignment  and
transfer is not contrary to or in conflict  with the  Partnership  Agreements or
any other agreement;

         (b) No  financing  statement  or other  instrument  similar  in  effect
covering all or any part of the  Collateral is on file in any recording  office,
except such as may have been filed in favor of the Administrative Agent relating
to this Agreement or those in favor of Prime Administrative Agent;

     (c) This  Agreement  has been duly executed and delivered by Pledgor and is
the legal and binding  obligation of Pledgor  enforceable in accordance with its
terms;



<PAGE>


         (d) Upon  execution  of this  Agreement  and an  appropriate  financing
statement  by  Pledgor  and the  recording  of the  financing  statement  in the
appropriate  office,  the  Administrative  Agent  will  have a valid,  perfected
security  interest in the  Collateral,  subject  only to the prior lien of Prime
Administrative Agent;

         (e) Neither the  execution  and  delivery  of this  Agreement,  nor the
consummation of any of the transactions hereby contemplated, nor compliance with
the terms and provisions hereof, will contravene or materially conflict with (i)
any material  provision of law,  statute or  regulation  to which Pledgor or the
Partnerships  is  subject  or  (ii)  any  judgment,  license,  order  or  permit
applicable to Pledgor or the Partnerships.  No consent, approval,  authorization
or  order of any  court,  governmental  authority,  partner  or  third  party is
required that has not been received or taken (i) for the grant by Pledgor of the
Security  Interests,  (ii) for the  execution,  delivery or  performance of this
Agreement by Pledgor,  (iii) for the  perfection of the Security  Interests,  or
(iv) except for such notices as are required by the Code or the Loan  Agreement,
for  the  exercise  by the  Administrative  Agent  of its  rights  and  remedies
hereunder (provided,  however,  that the purchaser of the Collateral at any sale
thereof  pursuant to Section 5.4 hereof may be required to obtain the consent of
the partners in the  Partnerships  and/or satisfy other  conditions set forth in
the Partnership  Agreements prior to such purchaser's  admission as a partner in
the Partnership);

     (f) The chief  executive  office and principal place of business of Pledgor
is in Austin, Travis County, Texas; and

         (g) To the best  knowledge  and belief of  Pledgor,  Pledgor  has fully
performed each and every one of his obligations and duties under the Partnership
Agreements  on or prior to the date due;  Pledgor has not received any notice of
any  default  in  the  performance  of his  obligations  under  the  Partnership
Agreements or of any situation which could give rise to such an event of default
thereunder.

                                   ARTICLE IV

                               PLEDGOR'S COVENANTS

         Pledgor hereby covenants and agrees with the Administrative  Agent that
until the Secured Indebtedness is paid and performed in full:

         (a)  Pledgor  will not cause,  permit or consent  to any  amendment  or
modification  to the  Partnership  Agreements  in effect  as of the date  hereof
except as permitted in the Prime Loan Agreement;

         (b)  Pledgor  will  pay and  discharge  promptly  when  due all  taxes,
assessments,  forced contributions,  governmental charges, fines, penalties, and
any other lawful claims, of every  description,  payable by Pledgor with respect
to (or  which,  if not paid  could  result  in an  encumbrance  upon) any of the
Collateral, except as otherwise permitted by the terms of the Loan Agreement. In
the  event  that  Pledgor  should,  for any  reason,  fail to pay and  discharge
promptly any taxes,  assessments,  forced  contributions,  governmental charges,
fines,  or  penalties  when due  (subject  to the  provisions  of the Prime Loan
Agreement),  then the Administrative Agent shall be authorized, but shall not be
obligated, to pay the same, with full subrogation to all rights of any Person by
reason of such payment,  and the amounts so paid, together with interest thereon
as provided herein, shall be secured by the Security Interests;


<PAGE>


         (c) Pledgor will not sell, transfer, mortgage or otherwise encumber any
Collateral  in any manner,  except for the  security  interest in favor of Prime
Administrative  Agent,  without  first  obtaining  the  written  consent  of the
Administrative  Agent. Any written consent to any such sale, mortgage,  transfer
or  encumbrance  shall  not be  construed  to be a waiver of this  provision  in
respect of any subsequent proposed sale, mortgage, transfer or encumbrance;

         (d)  Pledgor  will,  at its  expense and in such manner and form as the
Administrative Agent may from time to time reasonably require, execute, deliver,
file  and  record  any  financing   statement,   specific  assignment  or  other
instruments,  certificates  or  papers  and take any  other  action  that may be
necessary or desirable,  or that the Administrative  Agent may from time to time
reasonably  request,  in order to  create,  preserve,  perfect or  validate  any
Security Interest or to enable the Administrative  Agent to exercise and enforce
its rights  hereunder with respect to any of the Collateral.  In the event,  for
any  reason,  that the law of any  jurisdiction  other  than the  State of Texas
becomes or is applicable to the Collateral,  or any part thereof, Pledgor agrees
to execute and deliver all such instruments and to do all such other things that
may be necessary or  appropriate  to preserve,  protect and enforce the Security
Interests of the Administrative  Agent under the law of such other jurisdiction,
to at least the same extent that the Security Interests would be protected under
the Code. To the extent permitted by applicable law,  Pledgor hereby  authorizes
the  Administrative  Agent  to  execute  and  file,  in the name of  Pledgor  or
otherwise,  Uniform Commercial Code financing statements that the Administrative
Agent in its sole  discretion  may deem  necessary  or  appropriate  to  further
perfect the Security Interests;

         (e) If Pledgor receives,  by virtue of being or having been an owner of
any of the Collateral, any notes, other instruments, options, cash distributions
or any other distribution,  resulting from a Capital Event (hereinafter defined)
Pledgor  shall  receive the same in trust for the benefit of the  Administrative
Agent,  shall immediately  notify the  Administrative  Agent of such receipt and
shall  immediately  take all such actions and execute all such  documents as the
Administrative  Agent deems  necessary or  appropriate  to continue or create as
perfected Liens, in favor of the Administrative Agent covering such notes, other
instruments, options, cash distributions, subject ony to the prior lien in favor
of the Prime  Administrative  Agent.  As used herein,  the term "Capital  Event"
shall mean any event generating or resulting in revenues not attributable to the
normal business operations of the Partnerships including without limitation, any
mortgaging of assets,  refinancing of existing  indebtedness of any Partnership,
condemnation of any assets of any Partnership, sale or transfer of any assets of
any Partnership outside the ordinary course of business, or payment of insurance
proceeds. At all times other than during the continuance of an Event of Default,
Pledgor shall be entitled to receive free from the security  interest hereof any
note, other  instrument,  option,  cash  distribution or any other  distribution
resulting from any event other than a Capital Event;

         (f) Pledgor will notify the  Administrative  Agent in writing  prior to
the removal of Pledgor's chief  executive  office or principal place of business
from the State of Texas;

         (g) Pledgor shall cause to be obtained any and all waivers and consents
necessary to make  effective the grant  contained in and to perfect the security
interest  granted to the  Administrative  Agent  pursuant to Section 2.1 hereof,
including without limitation,  all necessary waivers and consents from the other
partners, if any, of each Partnership;

         (h) Pledgor shall perform fully all obligations  imposed upon it by any
agreements  or  instruments  concerning  all or  any  part  of  the  Collateral,
including  without  limitation the Partnership  Agreements and shall maintain in
full force and effect all such agreements and  instruments,  and shall not amend
or modify,  or consent to the amendment or  modification  of such  agreements or
instruments, without the prior written consent of the Administrative Agent; and


<PAGE>


         (i)  Pledgor  shall  promptly  notify the  Administrative  Agent of any
material adverse change in any material fact or material circumstance  warranted
or represented by Pledgor in this Agreement or in any other writing furnished by
Pledgor to the  Administrative  Agent in connection  with the  Collateral or the
Secured Indebtedness,  and shall promptly notify the Administrative Agent of any
claim,  action or  proceeding  affecting  title to the  Collateral,  or any part
thereof,  or  the  Security  Interests  herein,  and,  at  the  request  of  the
Administrative  Agent, shall appear and defend, at Pledgor's  expense,  any such
action or proceeding.

                                    ARTICLE V

                    GENERAL AUTHORITY AND POWERS AND REMEDIES

         SECTION 5.1       Events of Default.
                           -----------------

         Pledgor shall be in default under this  Agreement upon the happening of
any of the  following  events  or  conditions  (hereinafter  called an "Event of
Default"):

         (a)      An Event of Default under the Loan Agreement shall occur; or

     (b) The ownership of any of the  Collateral  becomes  vested in a person or
entity other than Pledgor, except as permitted hereunder; or

         (c) The  Administrative  Agent's Liens in any of the Collateral  should
become  unenforceable,  or cease to be first priority Liens, subject only to the
prior lien of Prime Administrative Agent.

         SECTION 5.2 Right to Receive  Distributions.  The Administrative  Agent
shall  have the  right,  at any time  following  the  occurrence  and during the
continuation of an Event of Default,  to receive all payments and  distributions
made to Pledgor upon or with  respect to the  Collateral  and Pledgor  agrees to
take all such action as the  Administrative  Agent may reasonably deem necessary
or appropriate to give effect to such right.

         SECTION 5.3 General Authority.  Pledgor hereby irrevocably appoints the
Administrative  Agent,  and its  successors  and  assigns,  the true and  lawful
attorney-in-fact  of Pledgor,  with full power of  substitution,  in the name of
Pledgor,  for the sole  use and  benefit  of the  Administrative  Agent,  but at
Pledgor's expense,  to the extent permitted by law to exercise,  at any time and
from time to time  following the  occurrence  and during the  continuance  of an
Event of Default,  all or any of the following powers with respect to all or any
of the Collateral:

     (a) to ask,  demand,  sue for,  collect,  receive and give  acquittance and
receipts for any and all monies due or to become due upon or by virtue thereof;

     (b) to  receive,  endorse,  and  collect  any drafts or other  instruments,
documents and chattel paper, in connection with clause (a) preceding;

     (c) to  settle,  compromise,  compound,  prosecute  or defend any action or
proceeding with respect thereto;

         (d)  subject  to  Section  5.4  hereof,  to sell,  transfer,  assign or
otherwise  deal in or with  the  same  or the  proceeds  thereof  as  fully  and
effectually as if the Administrative Agent were the absolute owner thereof; and


<PAGE>


     (e) to extend  the time of payment  of any or all  thereof  and to make any
allowance and other adjustments with reference thereto.

In addition,  the  Administrative  Agent, at any time, either before or after an
Event of Default, shall have the right, together with such accountants and other
agents or representatives as they may from time to time designate,  to visit and
inspect the Partnerships'  properties,  assets, books, records and documents and
to discuss the Partnerships'  affairs,  finances and accounts with Pledgor's and
the Partnerships'  representatives,  officers or directors,  during all business
hours as the  Administrative  Agent  may  designate,  and to make and take  away
copies of the  Partnerships'  records  at the  Administrative  Agent's  expense.
Pledgor  shall  furnish  to  Administrative  Agent  any  information  reasonably
requested by the Administrative Agent in connection with the Collateral. Pledgor
will maintain complete and accurate books and records regarding the Collateral.

         SECTION 5.4       Remedies Upon Default.
                           ---------------------

         (a) If any Event of Default shall have occurred and is continuing,  the
Administrative  Agent,  at its option,  without demand,  presentment,  notice of
acceleration,  intention to  accelerate or other notice (which are fully waived)
may:

                  (1) exercise all the rights of a secured  party under the Code
         (whether  or not the Code is in effect in the  jurisdiction  where such
         rights are exercise, unless prohibited by applicable law).

     (2) apply  the  cash,  if any,  then  held by the  Administrative  Agent as
Collateral as specified in Section 5.6.

                  (3) sell all of the  Collateral  or any part thereof at public
         or private sale or at any broker's board or on any securities exchange,
         for cash,  upon  credit or for  future  delivery,  and at such price or
         prices as the  Administrative  Agent may reasonably deem  satisfactory.
         Upon the  Administrative  Agent's  demand,  Pledgor will take all steps
         necessary to prepare the  Collateral  for and  otherwise  assist in any
         proposed  disposition  of the  Collateral.  Any  holder of the  Secured
         Indebtedness  may be the  purchaser of any or all of the  Collateral so
         sold at any public sale (or, if the Collateral is of a type customarily
         sold in a  recognized  market or is of a type  which is the  subject of
         widely distributed standard price quotations,  at any private sale) and
         thereafter  hold the same  absolutely,  free from any right or claim of
         whatsoever kind. Any holder of the Secured  Indebtedness shall have the
         right to offset  the amount of its bid  against an equal  amount of the
         Secured Indebtedness held by such holder.


<PAGE>


         Pledgor agrees that, because of the Securities Act of 1933, as amended,
         or any other laws or regulations,  and for other reasons,  there may be
         legal  and/or  practical  restrictions  or  limitations  affecting  the
         Administrative  Agent in any attempts to dispose of certain portions of
         the  Collateral  and for the  enforcement  of their  rights.  For these
         reasons,  the Administrative Agent is hereby authorized by Pledgor, but
         not obligated,  upon the occurrence and during the  continuation  of an
         Event of Default,  to sell all or any part of the Collateral at private
         sale,  subject to  investment  letter or in any other manner which will
         not require the  Collateral,  or any part thereof,  to be registered in
         accordance  with the Securities  Act of 1933, as amended,  or the rules
         and  regulations   promulgated   thereunder,   or  any  other  laws  or
         regulations,  at a  reasonable  price  at such  private  sale or  other
         distribution in the manner  mentioned above.  Pledgor  understands that
         the  Administrative  Agent  may in its  discretion  approach  a limited
         number of potential purchasers and that a sale under such circumstances
         may  yield a lower  price  for the  Collateral,  or any  part or  party
         thereof,  than would  otherwise be obtainable if such  collateral  were
         either  afforded  to  a  larger  number  or  potential  purchasers,  or
         registered or sold in the open market. Pledgor agrees that such private
         sale  shall be deemed to have  been made in a  commercially  reasonable
         manner,  and that the  Administrative  Agent has no obligation to delay
         sale of any  Collateral to permit the issuer thereof to register it for
         public sale under any applicable federal or state securities laws.

         The  Administrative  Agent is authorized,  in connection  with any such
         sale (i) to restrict the prospective bidders on or purchasers of any of
         the Collateral to a limited number of sophisticated  investors who will
         represent and agree that they are  purchasing for their own account for
         investment  and not with a view to the  distribution  or sale of any of
         such Collateral and (ii) to impose such other limitations or conditions
         in connection with any such sale as the Administrative Agent reasonably
         deems  necessary  in order  to  comply  with  applicable  law.  Pledgor
         covenants  and agrees that it will execute and deliver  such  documents
         and take such other action as the Administrative Agent reasonably deems
         necessary  in order that any such sale may be made in  compliance  with
         applicable law. Upon any such sale the Administrative  Agent shall have
         the right to deliver,  assign and transfer to the purchaser thereof the
         Collateral  so sold.  Each  purchaser  at any such sale  shall hold the
         Collateral so sold absolutely,  free from any claim or right of Pledgor
         of  whatsoever  kind,  including  any equity or right of  redemption of
         Pledgor.  Pledgor,  to the extent  permitted by applicable  law, hereby
         specifically  waives all rights of redemption,  stay or appraisal which
         it has or may have under any law now existing or hereafter enacted.

         Pledgor   agrees   that  five  (5)  days'   written   notice  from  the
         Administrative Agent to Pledgor of the Administrative Agent's intention
         to make any such public or private sale or sale at a broker's  board or
         on a securities  exchange shall  constitute  "reasonable  notification"
         within the meaning of Section  9-504(c) of the Code.  Such notice shall
         (1) in case of a public  sale,  state the time and place fixed for such
         sale,  (2) in  case  of sale at a  broker's  board  or on a  securities
         exchange,  state the board or  exchange  at which  such a sale is to be
         made and the day on which the  Collateral,  or the  portion  thereof so
         being sold, will first be offered to sale at such board or exchange and
         (3) in the case of a private sale,  state the day after which such sale
         may be consummated.  Any such public sale shall be held at such time or
         times within ordinary business hours and at such place or places as the
         Administrative  Agent may fix in the notice of such  sale.  At any such
         sale,  the  Collateral  may be  sold in one  lot as an  entirety  or in
         separate parcels, as the Administrative Agent may reasonably determine.
         The  Administrative  Agent shall not be obligated to make any such sale
         pursuant to any such  notice.  The  Administrative  Agent may,  without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place  fixed  for the  sale,  and such  sale may be made at any time or
         place to which the same may be so adjourned.

         In case of any sale of all or any part of the  Collateral  on credit or
         for future  delivery,  the  Collateral  so sold may be  retained by the
         Administrative  Agent until the selling  price is paid by the purchaser
         thereof,  but the Administrative Agent shall not incur any liability in
         case  of the  failure  of  such  purchaser  to  take up and pay for the
         Collateral so sold and in case of any such failure, such Collateral may
         again be sold upon like notice.  The Administrative  Agent,  instead of
         exercising the power of sale herein conferred upon it, may proceed by a
         suit or suits at law or in equity to foreclose  the Security  Interests
         and sell the Collateral,  or any portion  thereof,  under a judgment or
         decree of a court or courts of competent jurisdiction.


<PAGE>


         (b)  Without  the  limiting  the   foregoing,   or  imposing  upon  the
Administrative  Agent any  obligations or duties not required by applicable law,
Pledgor acknowledges and agrees that, in foreclosing upon any of the Collateral,
or exercising  any other rights or remedies  provided the  Administrative  Agent
hereunder or under applicable law, the  Administrative  Agent may, but shall not
be required to (1) qualify or restrict prospective  purchasers of the Collateral
by requiring evidence of sophistication and/or  creditworthiness,  and requiring
the execution and delivery of confidentiality  agreements or other documents and
agreements as a condition to such prospective purchasers' receipt of information
regarding the Collateral or participation  in any public or private  foreclosure
sale process; (2) provide to prospective  purchasers the Partnership  Agreements
and business and financial information  regarding the Partnerships  available in
the files of the Administrative  Agent at the time of commencing the foreclosure
process,  without the requirement that the Administrative  Agent obtain, or seek
to  obtain,  any  updated  business  or  financial  information  or  Partnership
Agreements, or verify, or certify to prospective purchasers, the accuracy of any
such business or financial  information or Partnership  Agreements;  (3) sell at
foreclosure  all, or a portion but not all, of the rights,  titles and interests
of  Pledgor  in a  particular  Partnership  or group of  Partnerships;  it being
further  specifically  acknowledged  by Pledgor  that  limitations  or potential
limitations  on  the  transfer  of  certain  Collateral  under  the  Partnership
Agreements or other  applicable  agreements or law may limit the  Administrative
Agent's right or ability to foreclose  upon or sell certain  rights,  titles and
interests  of  Pledgor  in the  Partnerships;  (4)  offer  for  sale,  and sell,
partnership  interests  either with, or without,  first  employing an appraiser,
investment  banker, or broker with respect to the evaluation of Collateral,  the
solicitation of purchasers for Collateral, or the manner of sale of Collateral.

         (c) The  Administrative  Agent  shall  have all  rights,  remedies  and
recourse  granted in the Loan Agreement and the other Loan Documents or existing
at common law or equity (including  specifically those granted by the Code), and
such rights and  remedies (1) shall be  cumulative  and  concurrent,  (2) may be
pursued separately,  successively or concurrently  against Pledgor and any party
obligated to pay or perform the Obligations, any of the Collateral, or any other
security  for  any  of  the   Obligations,   at  the  sole   discretion  of  the
Administrative  Agent,  and (3) may be exercised  as often as occasion  therefor
shall arise, it being agreed by Pledgor that the exercise or failure to exercise
any such  rights  or  remedies  shall in no event be  construed  as a waiver  or
release thereof or of any other right, remedy or recourse.

         (d)  Notwithstanding  a  foreclosure  upon  any  of the  Collateral  or
exercise of any other remedy by the  Administrative  Agent in connection with an
Event of Default,  Pledgor shall not be subrogated  thereby to any rights of the
Administrative Agent against the Collateral or any other security for any of the
Obligations.  Pledgor shall not be deemed to be the owner of any interest in any
of  the  Obligations  until  all  of  the  Obligations  have  been  paid  to the
Administrative Agent and are fully performed and discharged.

         (e)  All  recitals  in  any  instrument  of  assignment  or  any  other
instrument executed by the Administrative  Agent incident to the sale, transfer,
assignment or other  disposition  or  utilization  of the Collateral or any part
thereof  hereunder  shall be presumptive  evidence of the matters stated therein
and all  prerequisites  of such sale or other action  contained in such recitals
shall be presumed to have been performed or to have occurred.


<PAGE>


         SECTION  5.5  Waivers  by  Pledgor.  In case of any  Event of  Default,
neither Pledgor nor anyone claiming by, through or under Pledgor,  to the extent
Pledgor  may  lawfully  so  agree,  shall or will set up,  claim or seek to take
advantage of any appraisement,  valuation, stay, extension or redemption law now
or hereafter in force in any locality  where any of the  Collateral  is situated
for purposes of applicable law, in order to prevent or hinder the enforcement of
this  Agreement,  or the  absolute  sale of the  Collateral,  or the  final  and
absolute putting into possession  thereof,  immediately  after such sale, of the
purchaser thereof;  and Pledgor in Pledgor's own right and for all who may claim
under Pledgor, hereby waives, to the fullest extent that Pledgor may lawfully do
so, the benefit of any and all right to have the  Collateral  marshaled upon any
enforcement of the Security  Interests  herein granted,  and Pledgor agrees that
the  Administrative  Agent or any  court  having  jurisdiction  to  enforce  the
Security Interests may sell the Collateral in parts or as an entirety.

         SECTION 5.6  Application of Proceeds.  The  Administrative  Agent shall
apply  the  proceeds  of any  foreclosure  sale or  other  realization  upon the
Collateral  as follows  (as  modified,  if  necessary,  by the  requirements  of
applicable law):

         (a) First,  to the payment of all reasonable  costs and expenses of any
foreclosure   and  collection   hereunder  and  all  proceedings  in  connection
therewith, including reasonable compensation to Administrative Agent's counsel;

         (b) Then,  to the  reimbursement  of the  Administrative  Agent for all
disbursements made by the Administrative  Agent for taxes,  assessments or liens
superior to the Security Interests and which the Administrative Agent shall deem
expedient to pay;

     (c) Then, to the  reimbursement of the  Administrative  Agent for any other
disbursements  made by, or reasonable  expenses incurred by, the  Administrative
Agent in accordance with the terms hereof;

     (d) Then, to the Prime  Administrative  Agent until all secured obligations
of Pledgor to it and the Prime Lenders are paid;

     (e) Then,  to the Secured  Indebtedness,  in any manner  determined  by the
Administrative Agent in its sole discretion; and

     (f) The remainder of such proceeds, if any, shall be paid to Pledgor.

         The foregoing  application  provisions shall apply not only to proceeds
resulting from foreclosure but also to proceeds or distributions  resulting from
any other claim,  (including claims made in bankruptcy  proceedings),  action or
proceeding  to  enforce  or  protect  the  Administrative  Agent's  lien  in the
Collateral.

         SECTION  5.7  Enforcement  of  Secured  Indebtedness.  Nothing  in this
Agreement  shall affect or impair the  unconditional  and absolute  right of the
Administrative  Agent to enforce the Secured  Indebtedness  as and when the same
shall become due in accordance  with the terms of the Loan Documents  whether by
acceleration or otherwise.

                                   ARTICLE VI

                                  MISCELLANEOUS

         SECTION 6.1 Terms Commercially Reasonable.  The terms of this Agreement
shall be deemed  commercially  reasonable  within  the  meaning  of the  Uniform
Commercial Code in effect and applicable hereto.

         SECTION 6.2 Headings.  The headings of articles and sections herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope or intent of any provision of this Agreement.


<PAGE>


         SECTION   6.3   Amendments.   No   change,   amendment,   modification,
cancellation  or discharge of any  provision  of this  Agreement  shall be valid
unless consented to in writing by the Administrative  Agent and Pledgor (subject
to the terms of the Loan Agreement).

         SECTION  6.4  Assignment  of the  Administrative  Agent's  Rights.  The
Administrative  Agent  shall have the right to assign all or any  portion of its
rights  under  this  Agreement  to  any  subsequent  holder  or  holders  of the
Obligations.

         SECTION  6.5 Parties in  Interest.  As and when used  herein,  the term
"Pledgor"  shall mean and include  Pledgor  herein named and his  successors and
permitted assigns,  and the term  "Administrative  Agent" shall mean and include
the  Administrative  Agent herein named and his successors and assigns,  and all
covenants and  agreements  herein shall be binding upon and inure to the benefit
of Pledgor and the Administrative  Agent and their respective assigns,  provided
that  Pledgor  shall have no right to assign his rights  hereunder  to any other
Person  except  in  connection  with  a  transfer  of the  Collateral  permitted
hereunder.

         SECTION  6.6  APPLICABLE  LAWS.  THIS  AGREEMENT  SHALL  BE  CONSTRUED,
INTERPRETED  AND  ENFORCED  UNDER AND PURSUANT TO THE LAWS OF THE STATE OF TEXAS
AND  APPLICABLE  FEDERAL LAW. IF ANY  PROVISION OF THIS  AGREEMENT IS HELD TO BE
INVALID  OR  UNENFORCEABLE,   THE  VALIDITY  AND  ENFORCEABILITY  OF  THE  OTHER
PROVISIONS OF THIS AGREEMENT SHALL REMAIN UNAFFECTED.

         SECTION 6.7 Notices.  Any notices or other  communications  required or
permitted to be given by this Agreement or any other  documents and  instruments
referred  to herein  must be given in  accordance  with  Section  11 of the Loan
Agreement, to the address of such party as follows:

         If to the Administrative Agent:       515 Congress Avenue, 11th Floor

                                               Austin, Texas 78701

                                               Attn: Wade Morgan

         If to Pledgor:                        1301 Capital of Texas Highway

                                               Suite C-300

                                               Austin, Texas 78746-6550

                                               Attn: Treasurer

         SECTION 6.8  Financing  Statement.  The  Administrative  Agent shall be
entitled  at any  time to file a  photographic  or  other  reproduction  of this
Agreement as a financing statement,  but the failure of the Administrative Agent
to do so shall not impair the validity or enforceability of this Agreement.

         SECTION  6.9  Obligations  Absolute.  All  rights and  remedies  of the
Administrative  Agent hereunder,  and all obligations of the Pledgor  hereunder,
shall be absolute and unconditional irrespective of:

               (a) any lack of validity or  enforceability of the Loan Agreement
          or any  of  the  other  Loan  Documents  or  any  other  agreement  or
          instrument relating to any of the foregoing;

                  (b) any change in the time, manner, or place of payment of, or
         in any  other  term of,  all or any of the  Obligations,  or any  other
         amendment  or waiver of or any consent to any  departure  from the Loan
         Agreement or any of the other Loan Documents;


<PAGE>


               (c) any exchange, release, or nonperfection of any Collateral, or
          any release or amendment or waiver of or consent to any departure from
          any guarantee, for all or any of the Obligations; or

                  (d) any other circumstance  (other than payment in full of the
         Obligations) that might otherwise constitute a defense available to, or
         a discharge of, Pledgor.

         SECTION 6.10  Counterparts.  This Agreement may be executed in multiple
counterparts,  each of which shall be deemed to be an original, but all of which
shall  constitute  one and the  same  instrument,  and in  making  proof of this
Agreement it shall not be necessary to produce or account for more than one such
counterpart.

         SECTION  6.11 ENTIRE  AGREEMENT.  THIS  AGREEMENT  EMBODIES  THE FINAL,
ENTIRE  AGREEMENT  OF  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  WITH  RESPECT TO
PLEDGOR'S PLEDGE OF THE PLEDGED  PARTNERSHIP  INTERESTS AND RESTATES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN OR ORAL,  RELATING TO THE  SUBJECT  MATTER  HEREOF.  THIS  AGREEMENT  IS
INTENDED  BY  PLEDGOR,  THE  AGENTS  AND THE  LENDERS  AS A FINAL  AND  COMPLETE
EXPRESSION  OF THE TERMS OF THIS  AGREEMENT,  AND NO COURSE OF  DEALING  BETWEEN
PLEDGOR,  THE  AGENTS  OR THE  LENDERS,  NO  COURSE  OF  PERFORMANCE,  NO  TRADE
PRACTICES,  AND  NO  EVIDENCE  OF  PRIOR,  CONTEMPORANEOUS  OR  SUBSEQUENT  ORAL
AGREEMENTS OR  DISCUSSIONS  OR OTHER  EXTRINSIC  EVIDENCE OF ANY NATURE SHALL BE
USED TO CONTRADICT, VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS AGREEMENT. THERE
ARE NO ORAL AGREEMENTS AMONG PLEDGOR, THE AGENTS AND THE LENDERS.

                     [REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGES FOLLOW.]


<PAGE>



                          Pledge and Security Agreement

         IN WITNESS  WHEREOF,  Pledgor has executed this Agreement as of the day
and year first above written.

                                    PLEDGOR:

                                                     OHIO LITHO, INC.,
                                                       a Delaware corporation

                                                     By: /s/ Teena E. Belcik
                                                              Teena E. Belcik
                                                              Treasurer


<PAGE>



                                                                       Exhibit A



                                    EXHIBIT A

                                  PARTNERSHIPS

Ohio Mobile Lithotripter, Ltd.

Ohio Mobile Lithotripter II, Ltd.




<PAGE>



                                                                       Exhibit B



                                    EXHIBIT B

                             PARTNERSHIP AGREEMENTS

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter,  Ltd. dated August 1, 1991, as amended by First Amendment to First
Amended and Restated  Agreement of Limited  Partnership dated as of December 31,
1992

Certificate of Limited Partnership of Ohio Mobile  Lithotripter,  Ltd. dated May
21, 1991

First  Amended and  Restated  Agreement  of Limited  Partnership  of Ohio Mobile
Lithotripter II, Ltd.

Certificate of Limited  Partnership of Ohio Mobile  Lithotripter  II, Ltd. dated
August 23, 1995



                           Borrower Security Agreement

                           BORROWER SECURITY AGREEMENT

         THIS BORROWER SECURITY  AGREEMENT (the "Agreement") dated as of January
31, 2000, is executed by PRIME REFRACTIVE MANAGEMENT, L.L.C., a Delaware limited
liability company (the "Borrower"),  for the benefit of BANK OF AMERICA, N.A., a
national  banking  association  ("B of A"), not in its  individual  capacity but
solely as administrative agent for itself and each of the other Lenders (each, a
"Lender" and  collectively,  the "Lenders") as defined in the Loan Agreement (as
hereinafter defined) (in such capacity, together with its successors and assigns
in such capacity, the "Administrative Agent").

                                R E C I T A L S:
                                 - - - - - - - -

         A. Borrower,  B of A, as  administrative  agent,  BankBoston,  N.A., as
documentation  agent,  and the  Lenders  have  entered  into that  certain  Loan
Agreement  dated  January  __,  2000,  (as the  same may be  amended,  restated,
extended,  supplemented  or modified from time to time,  the "Loan  Agreement"),
pursuant to which the Lenders have agreed to make an advancing  term loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Fourteen Million and 00/100 Dollars ($14,000,000.00).

     B. The Agents and the Lenders have conditioned  their obligations under the
Loan  Agreement  upon  the  execution  and  delivery  of this  Agreement  by the
Borrower.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

                                    ARTICLE I

                                   Definitions

         Section 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         Section 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.

     Section  1.3  Additional  Definitions.  As  used  in  this  Agreement,  the
following terms shall have the following meanings:



<PAGE>





                                        3

                           Borrower Security Agreement

                  "Accounts"  means any  "account,"  as such term is  defined in
Article 9 of the UCC, now owned or hereafter  acquired by the Borrower,  and, in
any event, shall include, without limitation, each of the following, whether now
owned or hereafter  acquired by the Borrower:  (a) all rights of the Borrower to
payment for goods sold or leased or services rendered,  whether or not earned by
performance;  (b) all accounts receivable of the Borrower; (c) all rights of the
Borrower to receive any payment of money or other form of consideration; (d) all
security pledged,  assigned, or granted to or held by the Borrower to secure any
of the foregoing;  (e) all guaranties of, or  indemnifications  with respect to,
any of the foregoing;  and (f) all rights of the Borrower as an unpaid seller of
goods or  services,  including,  but not  limited  to, all rights of stoppage in
transit, replevin, reclamation, and resale.

                  "Chattel  Paper"  means any  "chattel  paper," as such term is
defined  in  Article  9 of the UCC,  now  owned  or  hereafter  acquired  by the
Borrower.

                  "Collateral" has the meaning  specified in Section 2.1 of this
Agreement.

                  "Document"  means any  "document,"  as such term is defined in
Article  9 of the  UCC,  now  owned  or  hereafter  acquired  by  the  Borrower,
including,  without limitation, all documents of title and warehouse receipts of
the Borrower.

                  "Equipment"  means any "equipment," as such term is defined in
Article 9 of the UCC,  now owned or hereafter  acquired by the Borrower  and, in
any  event,  shall  include,  without  limitation,  all  machinery,   equipment,
furnishings,  and fixtures  now owned or hereafter  acquired by the Borrower and
any and all additions,  substitutions, and replacements of any of the foregoing,
wherever located, together with all attachments,  components,  parts, equipment,
and accessories installed thereon or affixed thereto.

                  "General Intangibles" means any "general intangibles," as such
term is defined in Article 9 of the UCC, now owned or hereafter  acquired by the
Borrower  and, in any event,  shall  include,  without  limitation,  each of the
following,  whether now owned or hereafter acquired by the Borrower:  (a) all of
the Borrower's  patents,  patent  applications,  patent  rights,  service marks,
trademarks,  trade names, trade secrets,  intellectual property,  registrations,
goodwill,  copyrights,  franchises,  licenses, permits, proprietary information,
customer  lists,  designs,  and  inventions;  (b) all of the  Borrower's  books,
records, data, plans, manuals, computer software, and computer programs; (c) all
of the  Borrower's  contract  rights;  (d)  all of  the  Borrower's  partnership
interests,  joint venture,  limited liability  company,and  membership interests
(but only to the  extent  not  otherwise  pledged  to the  Administrative  Agent
pursuant  to  a  separate  pledge  or  security  agreement),  deposit  accounts,
investment accounts, and certificates of deposit; (e) all rights of the Borrower
to payment under letters of credit and similar  agreements;  (f) all tax refunds
and tax refund  claims of the  Borrower;  (g) all choses in action and causes of
action of the Borrower  (whether  arising in contract,  tort,  or otherwise  and
whether  or not  currently  in  litigation)  and all  judgments  in favor of the
Borrower;  (h) all  rights  and  claims of the  Borrower  under  warranties  and
indemnities;  and (i) all rights of the Borrower under any insurance, surety, or
similar contract or arrangement.

                  "Instrument"  means any  "instrument," as such term is defined
in Article 9 of the UCC and any note  payable to Borrower or its order  together
with all collateral  securing such note and all agreements and documents related
thereto or arising therefrom, now owned or hereafter acquired by the Borrower.

                  "Inventory"  means any "inventory," as such term is defined in
Article 9 of the UCC, now owned or hereafter  acquired by the Borrower,  and, in
any event, shall include, without limitation, each of the following, whether now
owned or hereafter  acquired by the Borrower:  (a) all goods and other  personal
property  of the  Borrower  that are  held for sale or lease or to be  furnished
under any contract of service; (b) all raw materials, work-in-process,  finished
goods,  inventory,  supplies,  and materials of the Borrower;  (c) all wrapping,
packaging,  advertising,  and shipping materials of the Borrower;  (d) all goods
that have been  returned  to,  repossessed  by, or  stopped  in  transit  by the
Borrower; and (e) all Documents evidencing any of the foregoing.

                  "Investment  Property"  means  "investment  property," as such
term is defined in Section 9.115(a)(6) of the Texas Business and Commerce Code.


<PAGE>


                  "Motor Vehicle" means all cars,  trucks,  vans and other motor
vehicles now owned or hereafter  acquired by the Borrower  which are used by the
Borrower for the transfer of lithotripters  and lithotripsy  related  equipment,
including without limitation,  those motor vehicles listed on Schedule 1 hereto,
and  any and all  attachments,  components,  parts,  equipment  and  accessories
installed thereon or affixed thereto.

                  "Proceeds"  means any  "proceeds,"  as such term is defined in
Article 9 of the UCC and, in any event,  shall  include,  but not be limited to,
(a) any and all  proceeds of any  insurance,  indemnity,  warranty,  or guaranty
payable to the Borrower from time to time with respect to any of the Collateral,
(b) any and all payments (in any form whatsoever) made or due and payable to the
Borrower from time to time in  connection  with any  requisition,  confiscation,
condemnation, seizure, or forfeiture of all or any part of the Collateral by any
Governmental  Authority  (or any  person  acting  under  color  of  Governmental
Authority),  and (c) any and all other amounts from time to time paid or payable
under or in connection with any of the Collateral.

                  "Securities" means all shares of stock of any Person now owned
or hereafter acquired by the Borrower including, without limitation, each of the
shares listed on Schedule 2 hereto,  and all dividends,  cash,  stock dividends,
instruments and other investment property from time to time received, receivable
by, or otherwise  distributed  to the Borrower for its own account in respect of
or in exchange for any or all of such shares, and the certificates  representing
such shares.

                  "UCC"  means the Uniform  Commercial  Code as in effect in the
State of Texas or, if so required with respect to any  particular  Collateral by
mandatory  provisions of  applicable  law, as in effect in the  jurisdiction  in
which such Collateral is located.

                                   ARTICLE II

                          Security Interest and Pledge

         Section 2.1 Security  Interest and Pledge.  The Borrower hereby pledges
and grants to the Administrative Agent, for the pro rata benefit of the Lenders,
a lien on and  security  interest in all of the  Borrower's  right,  title,  and
interest  in and to the  following,  whether now owned or  hereafter  arising or
acquired and wherever located (collectively, the "Collateral"):

                  (a)      all Accounts;

                  (b)      all Chattel Paper;

                  (c)      all Instruments;

                  (d)      all General Intangibles and all Securities;

                  (e)      all Investment Property;

                  (f)      all Documents;

     (g) all Equipment, including, without limitation, all Motor Vehicles;

                  (h)      all Inventory;


<PAGE>


     (i) all other goods and personal  property of the Borrower whether tangible
or intangible; and

                  (j) all Proceeds and products of any or all of the foregoing.

         Section 2.2  Secured  Indebtedness.  The  Collateral  shall  secure the
following  obligations,   indebtedness,   and  liabilities  (whether  at  stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

                  (a)      the Obligations;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the Collateral, collect the
obligations herein described, and enforce this Agreement; and

     (c) all extensions, renewals, and modifications of any of the foregoing.

         Section 2.3 Borrower  Remains Liable.  Notwithstanding  anything to the
contrary  contained  herein,  (a) the  Borrower  shall  remain  liable under the
contracts  and  agreements  included in the  Collateral  to the extent set forth
therein to perform  all of its duties  and  obligations  thereunder  to the same
extent as if this  Agreement  had not been  executed,  (b) the  exercise  by the
Administrative  Agent of any of its  rights  hereunder  shall  not  release  the
Borrower  from  any of  its  duties  or  obligations  under  the  contracts  and
agreements included in the Collateral,  and (c) neither the Administrative Agent
nor any Lender shall have any obligation or liability under any of the contracts
and agreements included in the Collateral by reason of this Agreement, nor shall
the  Administrative  Agent or any  Lender be  obligated  to  perform  any of the
obligations  or  duties  of the  Borrower  thereunder  or to take any  action to
collect or enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         Representations and Warranties

         To induce the Administrative Agent to enter into this Agreement and the
Agents and the Lenders to enter into the Loan Agreement, the Borrower represents
and warrants to the Administrative Agent that:

         Section 3.1 Title.  The  Borrower  is, and with  respect to  Collateral
acquired  after the date hereof the Borrower  will be, the legal and  beneficial
owner of the Collateral free and clear of any Lien,  security interest,  pledge,
claim or other  encumbrance  (except for Liens  permitted  by Section 9.2 of the
Loan  Agreement  and  liens in  favor  of the  Prime  Administrative  Agent  (as
hereinafter defined)) or, with respect to the Securities, any right or option on
the part of any Person (other than the Lenders) to purchase or otherwise acquire
the Securities or any part thereof,  except for the security  interests  granted
hereunder,  Liens permitted by Section 9.2 of the Loan  Agreement,  and liens in
favor of the Prime Administrative Agent (as hereinafter defined).  The liens and
security  interests  granted  herein are  subject and  subordinate  to the liens
granted in favor of Bank of America,  N.A.,  as  Administrative  Agent under the
Fourth  Amended and  Restated  Loan  Agreement  dated as of the date hereof (the
"Prime Loan  Agreement")  among Prime Medical  Services,  Inc., Bank of America,
N.A., as Administrative Agent (the "Prime  Administrative  Agent"),  BankBoston,
N.A., as Documentation Agent, and the lenders from time to time party thereto.


<PAGE>


         Section 3.2 Accounts.  Unless the Borrower has given the Administrative
Agent written  notice to the contrary,  whenever the security  interest  granted
hereunder  attaches  to an  Account,  the  Borrower  shall  be  deemed  to  have
represented and warranted to the Administrative  Agent as to each and all of its
Accounts  that (a) each Account is genuine and in all respects  what it purports
to be, (b) each Account  represents the legal,  valid, and binding obligation of
the account  Borrower  evidencing  indebtedness  unpaid and owed by such account
Borrower  arising out of the performance of labor or services by the Borrower or
the  sale or lease of goods by the  Borrower,  (c) the  amount  of each  Account
represented as owing is the correct amount  actually and  unconditionally  owing
except for normal trade  discounts  granted in the ordinary  course of business,
and (d) no Account is subject to any offset, counterclaim, or other defense.

         Section 3.3 Rule 144 Securities. With respect to all Collateral that is
Securities  which are subject to Rule 144 under the  Securities  Act of 1933, as
such rule and act are amended at the time in question and any successor in whole
or in part thereto, (a) the Borrower is the beneficial and record owner thereof,
free and clear of any Liens or transfer restrictions (other than restrictions on
the amount thereof which may be sold, and the manner in which sales may be made,
imposed by such Rule 144), (b) the Borrower  acquired such  Securities  directly
from the  issuer  thereof  more than two (2) years  prior to the date  hereof in
transactions  not  involving  any public  offering,  (c) the  Borrower  paid the
purchase  price  therefor  in cash  more  than two (2)  years  prior to the date
hereof,  (d) since such date of  acquisition,  the  Borrower has not had a short
position in, or any put or option to dispose of, any capital stock of any issuer
thereof or Securities  convertible into capital stock of any issuer thereof, (e)
neither the Borrower,  nor any person or entity, the sales of which are required
by Rule 144 to be  aggregated  with  the  sales  of the  Borrower,  has sold any
capital  stock of any  issuer of such  Securities  during  the period of six (6)
months  prior to the date  hereof,  other than sales  pursuant  to an  effective
registration  statement under the Securities Act of 1933, as amended, and (f) to
the Borrower's best  knowledge,  each issuer of such Securities has timely filed
all reports  required  to be filed by it under the  Securities  Exchange  Act of
1934, as amended.

         Section 3.4  Financing  Statements.  No financing  statement,  security
agreement,  or other Lien instrument  covering all or any part of the Collateral
is on file in any public  office,  except as may have been filed in favor of the
Prime Administrative Agent, any lender under the Prime Agreement, Administrative
Agent, or any Lender pursuant to this Agreement. The Borrower has not within the
past five (5) years had a trade name or done business  under any name other than
its legal name set forth at the beginning of this Agreement.

         Section  3.5  Principal  Place  of  Business.  The  principal  place of
business and chief  executive  office of the Borrower,  and the office where the
Borrower keeps its books and records,  is located at the address of the Borrower
shown on the signature pages of this Agreement.

         Section 3.6 Location of Collateral.  All Inventory and Equipment of the
Borrower are located at the places specified on Schedule 3 hereto.  The Borrower
has exclusive possession and control of its Inventory and Equipment. None of the
Inventory or  Equipment  of the Borrower is evidenced by a Document  (including,
without limitation,  a negotiable  document of title). All Instruments,  Chattel
Paper,  Securities and certificates of title of the Borrower have been delivered
to the Prime Administrative Agent, to perfect on its behalf and on behalf of the
Administrative Agent.


<PAGE>


         Section  3.7  Perfection.  Upon the filing of Uniform  Commercial  Code
financing  statements in the jurisdictions listed on Schedule 4 attached hereto,
and upon the  Administrative  Agent's  obtaining  possession  of all  Documents,
Instruments,  Chattel  Paper,  Securities  and  certificates  of  title  of  the
Borrower,   and  upon  the  Administrative  Agent's  obtaining  control  of  all
Investment Property,  the security interest in favor of the Administrative Agent
created  herein will  constitute  a valid and  perfected  Lien upon and security
interest in the Collateral,  subject to no equal or prior Lien,  except in favor
of the Prime  Administrative  Agent and as  permitted by Section 9.2 of the Loan
Agreement.

         Section 3.8 Independent Investigation.  The Borrower has, independently
and  without  reliance  upon any of the Agents or any Lender and based upon such
documents  and  information  as it has deemed  appropriate,  made its own credit
analysis  and  decision to enter into this  Agreement.  There are no  conditions
precedent to the full  effectiveness  of this Agreement that have not been fully
and permanently satisfied.

         Section 3.9  Litigation.  Except as  disclosed  on Schedule  7.5 to the
Prime  Agreement,  there  is  no  litigation,   investigation,  or  governmental
proceeding  threatened  against the Borrower or any of its  properties  which if
adversely  determined  would have a material adverse effect on the Collateral or
the financial condition,  operations,  or business of the Borrower, any Material
Subsidiary or the Companies taken as a whole.

                                   ARTICLE IV

                                    Covenants

         The Borrower  covenants and agrees with the  Administrative  Agent that
until the Secured Indebtedness is paid and performed in full and the Commitments
have terminated:

         Section 4.1  Encumbrances.  Except as  permitted  by Section 9.2 of the
Loan  Agreement  and  liens in  favor of the  Prime  Administrative  Agent,  the
Borrower  shall not create,  permit,  or suffer to exist,  and shall  defend the
Collateral  against,  any Lien,  security interest,  or other encumbrance on the
Collateral,  and shall defend the  Borrower's  rights in the  Collateral and the
Administrative  Agent's security  interest in the Collateral  against the claims
and demands of all Persons.  The Borrower  shall do nothing to impair the rights
of the Administrative Agent in the Collateral.

         Section 4.2 Delivery.  Prior to or concurrently  with the execution and
delivery of this Agreement,  Borrower shall deliver to the Prime  Administrative
Agent to acknowledge the  Administrative  Agent's lien and security  interest in
all  certificates  identified  on  Schedule 2 hereto,  with all  Chattel  Paper,
Instruments and Documents of the Borrower.


<PAGE>


         Section 4.3 Modification of Accounts. The Borrower shall, in accordance
with prudent  business  practices,  endeavor to collect or cause to be collected
from each  account  Borrower  under its  Accounts,  as and when due, any and all
amounts  owing under such  Accounts.  Without the prior  written  consent of the
Administrative  Agent, the Borrower shall not (a) grant any extension of time on
any  Account  for any payment or grant  extensions  of time for  payments on its
Accounts  which  cause the  aggregate  amount of all  payments  extended  by the
Borrower  on its  Accounts  during any  fiscal  year of the  Borrower  to exceed
$150,000.00,  (b) compromise,  compound,  or settle any of the Accounts for less
than  the  full  amount  thereof;  provided,  however,  that  the  Borrower  may
compromise,  compound  or  settle  any  Account  which is an  amount  less  than
$50,000.00,  provided the aggregate  amount  compromised,  compounded or settled
during  any  fiscal  year of the  Borrower  shall not  exceed  $150,000.00,  (c)
release,  in whole or in part,  any Person  liable for  payment of an Account in
excess of $50,000.00,  (d) allow any credit or discount for payment with respect
to any Account in excess of $50,000.00,  other than trade  discounts  granted in
the ordinary course of business; provided, however, that the aggregate amount of
all credits or discounts  granted  during any fiscal year of the Borrower  shall
not exceed $150,000.00,  or (e) release any Lien, security interest, or guaranty
securing any Account in excess of $50,000.00.

         Section 4.4  Disposition  of  Collateral.  The Borrower shall not sell,
lease,  assign (by operation of law or otherwise),  or otherwise  dispose of, or
grant any option with respect to, the Collateral or any part thereof without the
prior written consent of the Administrative  Agent, except the Borrower may sell
Inventory in the ordinary course of business.

         Section 4.5  Distributions.  If the Borrower  shall become  entitled to
receive or shall receive any stock certificate  (including,  without limitation,
any certificate representing a stock dividend or distribution in connection with
any reclassification,  increase, or reduction of capital or issued in connection
with any  reorganization),  option or  rights,  whether  as an  addition  to, in
substitution  of, or an exchange for any  Collateral or otherwise,  the Borrower
agrees to accept the same as the  Administrative  Agent's  agent and to hold the
same in trust for the Administrative  Agent and to deliver the same forthwith to
the Prime Administrative Agent in the exact form received,  with the appropriate
endorsement  of the Borrower when  necessary  and/or  appropriate  undated stock
powers duly executed in blank, to be held by the Prime  Administrative  Agent on
its own behalf and on behalf of  Administrative  Agent as additional  Collateral
for the Secured Indebtedness, subject to the terms hereof. Any sums paid upon or
in respect of the Securities  upon the  liquidation or dissolution of the issuer
thereof shall be paid over to the Prime Administrative Agent to be held by it as
additional  Collateral for the Secured Indebtedness subject to the terms hereof;
and in case any  distribution  of capital  shall be made on or in respect of the
Securities  or any  property  shall be  distributed  upon or with respect to the
Securities  pursuant to any  recapitalization or reclassification of the capital
of the issuer thereof or pursuant to any  reorganization  of the issuer thereof,
the property so distributed shall be delivered to the Prime Administrative Agent
to be held by it, as additional Collateral for the Secured Indebtedness, subject
to the terms hereof.  All sums of money and property so paid or  distributed  in
respect of the Securities that are received by the Borrower shall, until paid or
delivered to the  Administrative  Agent (or the Prime  Administrative  Agent, so
long as it has a prior  lien),  be held by the  Borrower in trust as  additional
security for the Secured Indebtedness.


<PAGE>


         Section 4.6 Further Assurances. At any time and from time to time, upon
the  request  of  the  Administrative  Agent,  and at the  sole  expense  of the
Borrower,  the  Borrower  shall  promptly  execute and deliver all such  further
instruments,  agreements,  and  documents  and take such  further  action as the
Administrative  Agent may reasonably deem necessary or desirable to preserve and
perfect its security interest in the Collateral and carry out the provisions and
purposes of this  Agreement.  Without  limiting the generality of the foregoing,
the Borrower  shall:  (a) execute and deliver to the  Administrative  Agent such
financing  statements as the Administrative Agent may from time to time require;
(b) deliver and pledge to the Administrative  Agent (or the Prime Administrative
Agent,  so  long as it has a  prior  lien)  all  Documents  (including,  without
limitation,  negotiable  documents of title) evidencing  Inventory or Equipment;
(c) deliver and pledge to the Administrative  Agent (or the Prime Administrative
Agent, so long as it has a prior lien) all certificates of title required by the
Loan Agreement, Instruments and Chattel Paper of the Borrower with any necessary
endorsements; and (d) execute and deliver to the Administrative Agent such other
documents,   instruments,   and  agreements  as  the  Administrative  Agent  may
reasonably  require to perfect and maintain  the  validity,  effectiveness,  and
priority of the Loan Documents and the Liens intended to be created thereby. The
Borrower  authorizes the  Administrative  Agent to file one or more financing or
continuation statements,  and amendments thereto, relating to all or any part of
the Collateral  without the signature of the Borrower where  permitted by law. A
carbon,  photographic,  or  other  reproduction  of  this  Agreement  or of  any
financing  statement  covering  the  Collateral  or any  part  thereof  shall be
sufficient as a financing statement and may be filed as a financing statement.

         Section 4.7 Risk of Loss;  Insurance.  The Agents and the Lenders shall
not be responsible for any loss or damage to the Collateral. The Borrower shall,
at its own expense,  maintain  insurance  with  financially  sound and reputable
insurance  companies  in such  amounts  and  covering  such  risks as is usually
carried  by  corporations  engaged  in similar  businesses  and  owning  similar
properties in the same general areas in which the Borrower  operates  consistent
with past  practices  and to the extent  available  on  commercially  reasonable
terms,  provided  that  in  any  event  the  Borrower  will  maintain  workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance,  professional liability insurance and business interruption insurance
reasonably  satisfactory  to the  Administrative  Agent.  Each insurance  policy
covering  Collateral shall name the  Administrative  Agent as loss payee for the
benefit of the Lenders as its  interest  may appear and shall  provide that such
policy will not be canceled or reduced  without  thirty (30) days prior  written
notice to the Administrative Agent.

         Section  4.8   Inspection   Rights.   The  Borrower  shall  permit  the
Administrative  Agent and each Lender and their  respective  representatives  to
examine, inspect, and audit the Collateral and to examine, inspect, and copy the
Borrower's  books  and  records  at any  reasonable  time  and as  often  as the
Administrative Agent or any such Lender may desire. The Administrative Agent and
each Lender may at any time and from time to time contact account  Borrowers and
other  obligors to verify the  existence,  amounts,  and terms of the Borrower's
Accounts.

         Section 4.9 Corporate Changes.  The Borrower shall not change its name,
identity,  or corporate  structure  in any manner that might make any  financing
statement filed in connection with this Agreement  seriously  misleading  unless
the Borrower  shall have given the  Administrative  Agent thirty (30) days prior
written  notice  thereof  and shall  have  taken all  action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent to make  each  financing
statement not seriously misleading.  The Borrower shall not change its principal
place of business, chief executive office, or the place where it keeps its books
and records unless it shall have given the Administrative Agent thirty (30) days
prior written notice thereof and shall have taken all action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent  to cause  its  security
interest in the  Collateral to be perfected  with the priority  required by this
Agreement.

         Section 4.10 Books and Records;  Information.  The Borrower  shall keep
accurate and complete  books and records of the  Collateral  and the  Borrower's
business and financial  condition in accordance  with GAAP.  The Borrower  shall
from time to time at the  request  of the  Administrative  Agent  deliver to the
Administrative Agent such information  regarding the Collateral and the Borrower
as  the  Administrative  Agent  may  reasonably  request,   including,   without
limitation,  lists  and  descriptions  of the  Collateral  and  evidence  of the
identity and existence of the Collateral. The Borrower shall mark its records to
reflect the security interest of the Administrative Agent hereunder.

         Section 4.11      Equipment and Inventory.
                           -----------------------

                  (a) The Borrower shall keep the Equipment and Inventory at the
         locations  specified  on  Schedule 3 hereto or,  upon  thirty (30) days
         prior written notice to the Administrative  Agent, at such other places
         within  the  United  States of America  where all  action  required  to
         perfect the  Administrative  Agent's security interest in the Equipment
         and Inventory with the priority  required by this Agreement  shall have
         been taken.


<PAGE>


     (b) The Borrower  shall  maintain the Equipment and Inventory in accordance
with Section 8.3 of the Loan Agreement.

         Section 4.12 Warehouse  Receipts  Non-Negotiable.  The Borrower  agrees
that if any warehouse receipt or receipt in the nature of a warehouse receipt is
issued in respect of any of the Collateral, such warehouse receipt or receipt in
the nature  thereof shall not be  "negotiable"  (as such term is used in Section
7.104 of the Uniform  Commercial Code as in effect in any relevant  jurisdiction
or under relevant law).

         Section 4.13 Taxes and Claims.  The Borrower  shall pay and  discharge,
before the same become  delinquent,  (a) all material  taxes,  assessments,  and
governmental  charges  imposed upon it or upon any of its property,  and (b) all
material  lawful  claims  that,  if unpaid,  might become a Lien upon any of its
property;  provided,  however, that the Borrower shall not be required to pay or
discharge  any such  tax,  assessment,  or  governmental  charge  which is being
contested in good faith by proper  proceedings being diligently  pursued and for
which adequate reserves have been established in accordance with GAAP.

         Section 4.14  Compliance  with Laws.  The Borrower  shall comply in all
material respects with all material applicable laws, rules, regulations, orders,
and decrees of any Governmental Authority or arbitrator.

         Section 4.15 Compliance with  Agreements.  The Borrower shall comply in
all material respects with all agreements, contracts, and instruments binding on
it or affecting its properties or businesses,  except where the failure to do so
would not have a material adverse effect on the business,  condition  (financial
or otherwise), operations or properties of the Borrower, any Material Subsidiary
or the Companies (taken as a whole).

         Section  4.16  Notification.  Except as permitted by Section 9.2 of the
Loan Agreement and Section 9.2 of the Prime Loan  Agreement,  the Borrower shall
promptly notify the  Administrative  Agent of (a) any Lien,  security  interest,
encumbrance,  or claim that has attached to or been made or asserted against any
of the Collateral, (b) any material change in any of the Collateral,  including,
without  limitation,  any material damage to or loss of any material  portion of
the Collateral, (c) the occurrence of any other event that could have a material
adverse effect on the Collateral or the security interest created hereunder, and
(d) the occurrence or existence of any Default.

         Section 4.17  Collection of Accounts.  Except as otherwise  provided in
this Section or in any other Loan Document, the Borrower shall have the right to
collect  and  receive  payments  on  the  Accounts.   In  connection  with  such
collections,   the  Borrower  may  take  (and,  at  the  Administrative  Agent's
direction,  shall take) such actions as the Borrower or the Administrative Agent
may  reasonably  deem  necessary  or  advisable  to  enforce  collection  of the
Accounts.

         Section 4.18 Additional  Securities.  The Borrower shall not consent to
or approve the issuance of any  additional  shares of any class of capital stock
of the issuers of any of the Securities,  or any securities convertible into, or
exchangeable  for, any such shares or any warrants,  options,  rights,  or other
commitments  entitling  any Person to  purchase  or  otherwise  acquire any such
shares.


<PAGE>


         Section 4.19 Provide  Information.  The Borrower shall fully cooperate,
to  the  extent  reasonably  requested  by  the  Administrative  Agent,  in  the
completion  of any  notice,  form,  schedule,  or  other  document  filed by the
Administrative Agent on its own behalf or on behalf of the Borrower,  including,
without limitation,  any required notice or statement of beneficial ownership or
of the  acquisition of beneficial  ownership of the Securities and any notice of
proposed  sale of such  Securities  pursuant to Rule 144 as  promulgated  by the
Securities and Exchange Commission (the "SEC") under the Securities Act of 1933,
as amended. Without limiting the generality of the foregoing, the Borrower shall
furnish  to  the  Administrative   Agent  any  and  all  information  which  the
Administrative  Agent may  reasonably  request for  purposes of any such filing,
regarding the Borrower, the Securities, and any issuer of any of the Securities,
and the Borrower shall disclose to the Administrative Agent all material adverse
information  known by the Borrower with respect to the  operations of any issuer
of any of the Securities.

         Section  4.20  Notification  of Changes in  Beneficial  Ownership.  The
Borrower  shall  promptly  notify  the  Administrative  Agent  of  any  sale  of
securities  of any  Subsidiary  of the  Borrower  or by any Person  named on the
Borrower's   Rule  144   questionnaire   and  shall  furnish   promptly  to  the
Administrative  Agent a copy of any Form 144 filed in  respect of any such sale.
In addition,  if the Borrower or any other Person named in the  Borrower's  Rule
144 questionnaire shall file with the SEC a form or other document reporting any
change in the beneficial  ownership of the common stock of any Subsidiary of the
Borrower, the Borrower shall promptly furnish to the Administrative Agent a copy
of such form or document.

         Section 4.21 Restriction on Sales after Default. The Borrower shall not
sell or  suffer  or  permit  any  Person  named  in the  accompanying  Rule  144
questionnaire  to sell  any  shares  of the  same  class  of  securities  as the
Securities at any time after any Event of Default shall have occurred.

         Section  4.22  Fixtures.  For any  Collateral  that is a fixture  or an
accession  which has been  attached  to real  estate or other goods prior to the
perfection of the security interest granted in Section 2.1 hereof,  the Borrower
shall furnish to Administrative  Agent, upon demand, a disclaimer of interest in
each such fixture or accession and a consent in writing to the security interest
of Administrative  Agent therein,  signed by all persons and entities having any
interest  in such  fixture or  accession  by virtue of any  interest in the real
estate or other goods to which such fixture or accession has been attached.

         Section 4.23 Notation on Title  Certificates.  If certificates of title
are issued or outstanding  with respect to any of the  Collateral,  the Borrower
shall cause the security  interest  granted in Section 2.1 hereof to be properly
noted thereon.

                                    ARTICLE V

                       Rights of the Administrative Agent

         Section  5.1  Power  of  Attorney.   The  Borrower  hereby  irrevocably
constitutes  and  appoints  the  Administrative  Agent and any  officer or agent
thereof,   with   full   power  of   substitution,   as  its  true  and   lawful
attorney-in-fact  with full  irrevocable  power and authority in the name of the
Borrower  or in its own name,  to take any and all action and to execute any and
all documents and  instruments  which the  Administrative  Agent at any time and
from time to time deems  reasonably  necessary or desirable  to  accomplish  the
purposes of this  Agreement  if an Event of Default  shall have  occurred and be
continuing,  and, without limiting the generality of the foregoing, the Borrower
hereby  gives  the  Administrative  Agent  the  power and right on behalf of the
Borrower and in its own name to do any of the  following  (subject to the rights
of the Borrower  under  Sections 5.2 and 5.3 hereof),  without  notice to or the
consent of the  Borrower  if an Event of  Default  shall  have  occurred  and be
continuing:


<PAGE>


                  (a) to demand, sue for, collect, or receive in the name of the
         Borrower or in its own name,  any money or property at any time payable
         or  receivable  on account of or in exchange for any of the  Collateral
         and,  in  connection   therewith,   endorse  checks,   notes,   drafts,
         acceptances, money orders, documents of title, or any other instruments
         for the  payment  of  money  under  the  Collateral  or any  policy  of
         insurance;

     (b) to pay or  discharge  taxes,  Liens,  or other  encumbrances  levied or
placed on or threatened against the Collateral;

     (c) to notify post office authorities to change the address for delivery of
mail of the Borrower to an address designated by the Administrative Agent and to
receive,  open. and  subsequently  deliver to the Borrower mail addressed to the
Borrower; and

                  (d) (i) to direct  account  Borrowers  and any  other  parties
         liable for any payment  under any of the  Collateral to make payment of
         any and all  monies due and to become due  thereunder  directly  to the
         Administrative  Agent or as the Administrative Agent shall direct; (ii)
         to receive payment of and receipt for any and all monies,  claims,  and
         other  amounts  due and to  become  due at any  time in  respect  of or
         arising out of any Collateral;  (iii) to sign and endorse any invoices,
         freight  or  express  bills,  bills of  lading,  storage  or  warehouse
         receipts, drafts against Borrowers, assignments, proxies, stock powers,
         verifications,  and  notices  in  connection  with  accounts  and other
         documents  relating to the  Collateral;  (vi) to commence and prosecute
         any suit,  action,  or  proceeding  at law or in equity in any court of
         competent  jurisdiction  to collect the  Collateral or any part thereof
         and to enforce  any other  right in respect of any  Collateral;  (v) to
         defend any suit,  action,  or proceeding  brought  against the Borrower
         with respect to any Collateral;  (vi) to settle,  compromise, or adjust
         any suit,  action,  or  proceeding  described  above and, in connection
         therewith,  to give such  discharges or releases as the  Administrative
         Agent may deem appropriate; (vii) to exchange any of the Collateral for
         other   property  upon  any  merger,   consolidation,   reorganization,
         recapitalization,  or other  readjustment of the issuer thereof and, in
         connection therewith, deposit any of the Collateral with any committee,
         depositary,  transfer agent, registrar, or other designated agency upon
         such terms as the Administrative Agent may determine;  (viii) to add or
         release any guarantor,  indorser,  surety, or other party to any of the
         Collateral;  (ix) to renew,  extend,  or otherwise change the terms and
         conditions of any of the Collateral;  (x) to make, settle,  compromise,
         or  adjust  claims  under  any  insurance  policy  covering  any of the
         Collateral;  (xi) to sell,  transfer,  pledge,  make any agreement with
         respect to or otherwise  deal with any of the  Collateral  as fully and
         completely as though the  Administrative  Agent were the absolute owner
         thereof  for all  purposes,  and to do, at the  Administrative  Agent's
         option and the Borrower's  expense,  at any time, or from time to time,
         all acts and things which the  Administrative  Agent deems necessary to
         protect,   preserve,   or   realize   upon  the   Collateral   and  the
         Administrative   Agent's  security  interest  therein;   and  (xii)  to
         complete, execute and file with the SEC one or more notices of proposed
         sale of securities pursuant to Rule 144.


<PAGE>


         This power of attorney is a power coupled with an interest and shall be
irrevocable.  Neither the Administrative Agent nor any Lender shall be under any
duty  to  exercise  or  withhold  the  exercise  of any of the  rights,  powers,
privileges,  and options expressly or implicitly  granted to the  Administrative
Agent in this Agreement, and shall not be liable for any failure to do so or any
delay in doing so.  Neither  the  Administrative  Agent nor any Lender  shall be
liable for any act or  omission  or for any error of  judgment or any mistake of
fact or law in its  individual  capacity or in its capacity as  attorney-in-fact
except  acts or  omissions  resulting  from  its  gross  negligence  or  willful
misconduct.  This power of attorney is  conferred  on the  Administrative  Agent
solely to protect,  preserve,  and  realize  upon its  security  interest in the
Collateral. Neither the Administrative Agent nor any Lender shall be responsible
for any decline in the value of the Collateral and shall not be required to take
any steps to preserve rights against prior parties or to protect,  preserve,  or
maintain any security interest or Lien given to secure the Collateral.

         Section 5.2 Voting  Rights.  Unless and until an Event of Default shall
have occurred and be continuing,  the Borrower shall be entitled to exercise any
and all voting rights  pertaining to the  Securities or any part thereof for any
purpose not inconsistent with the terms of this Agreement or the Loan Agreement.
The  Administrative  Agent shall  execute and deliver to the  Borrower  all such
proxies and other  instruments  as the Borrower may  reasonably  request for the
purpose of  enabling  the  Borrower to exercise  the voting  rights  which it is
entitled to exercise pursuant to this Section.

         Section 5.3 Dividends.  Unless and until an Event of Default shall have
occurred and be continuing, the Borrower shall be entitled to receive and retain
the dividends on the Securities paid in cash out of earned surplus to the extent
and only to the extent that such dividends are permitted by the Loan Agreement.

         Section 5.4 Setoff,  Property Held by the Lenders.  The  Administrative
Agent and each  Lender  shall  have the right to set off and apply  against  the
Secured  Indebtedness,  at any time and without notice to the Borrower,  any and
all deposits (general or special, time or demand, provisional or final) or other
sums at any time  credited  by or owing  from  the  Administrative  Agent or any
Lender to the Borrower  whether or not the Secured  Indebtedness is then due. As
additional security for the Secured Indebtedness, the Borrower hereby grants the
Administrative  Agent  and  each  Lender  a  security  interest  in  all  money,
instruments,  and other  property of the Borrower  now or hereafter  held by the
Administrative Agent or any Lender, including without limitation,  property held
in  safekeeping.  In addition to the  Administrative  Agent's and each  Lender's
right of setoff  and as  further  security  for the  Secured  Indebtedness,  the
Borrower  hereby  grants to each of them a  security  interest  in all  deposits
(general or special,  time or demand,  provisional or final) of the Borrower now
or  hereafter  on deposit  with or held by any of them and all other sums at any
time credited by or owing from the any of them to the  Borrower.  The rights and
remedies of the  Administrative  Agent and each Lender hereunder are in addition
to other rights and remedies  (including,  without  limitation,  other rights of
setoff) which any of them may have.

         Section 5.5  Performance  by the Secured  Party.  If the Borrower shall
fail to perform any  covenant or  agreement  contained  in this  Agreement,  the
Administrative Agent, may, at the direction of the Required Lenders,  perform or
attempt to perform such covenant or agreement on behalf of the Borrower. In such
event, the Borrower shall, at the request of the Administrative  Agent, promptly
pay any amount expended by the Administrative  Agent or any Lender in connection
with such  performance  or attempted  performance to the  Administrative  Agent,
together with  interest  thereon at the Default Rate from and including the date
of such  expenditure to but excluding the date such expenditure is paid in full.
Notwithstanding  the  foregoing,   it  is  expressly  agreed  that  neither  the
Administrative  Agent nor any Lender shall have any liability or  responsibility
for the performance of any obligations of the Borrower under this Agreement.

                                   ARTICLE VI

                                     Default

         Section  6.1 Rights  and  Remedies.  If an Event of Default  shall have
occurred and be continuing,  the  Administrative  Agent shall have the following
rights and remedies:


<PAGE>


                  (a) In addition to all other  rights and  remedies  granted to
         the  Administrative  Agent  in  this  Agreement  or in any  other  Loan
         Document or by applicable law, the Administrative  Agent shall have all
         of the rights and remedies of a secured party under the UCC (whether or
         not the UCC applies to the affected  Collateral).  Without limiting the
         generality of the foregoing,  the Administrative  Agent may (i) without
         demand or notice to the Borrower,  collect, receive, or take possession
         of the  Collateral  or any  part  thereof  and  for  that  purpose  the
         Administrative   Agent  may  enter  upon  any  premises  on  which  the
         Collateral is located and remove the Collateral  therefrom or render it
         inoperable,  and/or  (ii)  sell,  lease,  or  otherwise  dispose of the
         Collateral,  or any part  thereof,  in one or more parcels at public or
         private  sale  or  sales,  at the  Administrative  Agent's  offices  or
         elsewhere,  for cash, on credit or for future  delivery,  and upon such
         other  terms  as  the   Administrative   Agent  may  deem  commercially
         reasonable. The Administrative Agent shall have the right at any public
         sale or sales,  and, to the extent  permitted by applicable law, at any
         private sale or sales,  to bid and become a purchaser of the Collateral
         or any part  thereof free of any right or equity of  redemption  on the
         part of the  Borrower,  which right or equity of  redemption  is hereby
         expressly waived and released by the Borrower.  Upon the request of the
         Administrative  Agent,  the Borrower  shall assemble the Collateral and
         make it available to the  Administrative  Agent at any place designated
         by the  Administrative  Agent  that  is  reasonably  convenient  to the
         Borrower and the  Administrative  Agent.  The Borrower  agrees that the
         Administrative  Agent shall not be obligated to give more than five (5)
         days written  notice of the time and place of any public sale or of the
         time after which any  private  sale may take place and that such notice
         shall constitute  reasonable notice of such matters. The Administrative
         Agent shall not be obligated to make any sale of Collateral if it shall
         determine  not to do so,  regardless of the fact that notice of sale of
         Collateral may have been given. The  Administrative  Agent may, without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place fixed for sale, and such sale may,  without  further  notice,  be
         made at the time and  place to  which  the same was so  adjourned.  The
         Borrower  shall  be  liable  for all  expenses  of  retaking,  holding,
         preparing  for  sale,  or the  like,  and all  attorneys'  fees,  legal
         expenses,   and  all  other   costs  and   expenses   incurred  by  the
         Administrative Agent or any Lender in connection with the collection of
         the Secured  Indebtedness  and the  enforcement  of the  Administrative
         Agent's and the  Lender's  rights  under this  Agreement.  The Borrower
         shall remain  liable for any  deficiency if the Proceeds of any sale or
         other disposition of the Collateral are insufficient to pay the Secured
         Indebtedness  in full.  The  Administrative  Agent and the  Lenders may
         apply the Collateral against the Secured Indebtedness in such order and
         manner as the  Administrative  Agent and the  Lenders  may  elect.  The
         Borrower waives all rights of marshaling,  valuation,  and appraisal in
         respect of the Collateral.

                  (b)  The  Administrative  Agent  may  cause  any or all of the
         Collateral  held  by  it  to  be  transferred  into  the  name  of  the
         Administrative Agent or the name or names of the Administrative Agent's
         nominee or nominees.

                  (c) The  Administrative  Agent  may  exercise  or  cause to be
         exercised  all voting,  consensual  and other  powers of  ownership  in
         respect  of the  Collateral  and  the  Borrower  shall  deliver  to the
         Administrative   Agent,  if  requested  by  the  Administrative  Agent,
         irrevocable proxies with respect to the Securities in form satisfactory
         to the Administrative Agent.

                  (d) The Administrative  Agent may collect or receive all money
         or  property  at any time  payable  or  receivable  on account of or in
         exchange for any of the Collateral, but shall be under no obligation to
         do so.


<PAGE>


                  (e) On any sale of the Collateral, the Administrative Agent is
         hereby  authorized to comply with any  limitation or  restriction  with
         which  compliance  is  necessary,  in the  view  of the  Administrative
         Agent's  counsel,  in order to avoid any violation of applicable law or
         in order to obtain any required approval of the purchaser or purchasers
         by any applicable Governmental Authority.

                  (f) The Borrower agrees that, because of the Securities Act of
         1933,  as  amended,  or any other  laws or  regulations,  and for other
         reasons,   there  may  be  legal  and/or   practical   restrictions  or
         limitations  affecting  the  Administrative  Agent in any  attempts  to
         dispose of certain  portions of the Securities and for the  enforcement
         of their rights. For these reasons,  the Administrative Agent is hereby
         authorized by the Borrower, but not obligated,  upon the occurrence and
         during the continuation of an Event of Default, to sell all or any part
         of the Securities at private sale,  subject to investment  letter or in
         any other  manner  which will not require the  Securities,  or any part
         thereof,  to be  registered in accordance  with the  Securities  Act of
         1933, as amended, or the rules and regulations  promulgated thereunder,
         or any other laws or regulations, at a reasonable price at such private
         sale or other  distribution in the manner mentioned above. The Borrower
         understands  that  the  Administrative  Agent  may  in  its  discretion
         approach a limited number of potential purchasers and that a sale under
         such  circumstances may yield a lower price for the Securities,  or any
         part or party  thereof,  than would  otherwise  be  obtainable  if such
         collateral  were  either  afforded  to a  larger  number  or  potential
         purchasers,  or  registered  or sold in the open  market.  The Borrower
         agrees  that such  private  sale shall be deemed to have been made in a
         commercially  reasonable manner, and that the Administrative  Agent has
         no  obligation  to delay  sale of any  Securities  to permit the issuer
         thereof to register it for public sale under any applicable  federal or
         state  securities  laws. The  Administrative  Agent is  authorized,  in
         connection with any such sale (a) to restrict the  prospective  bidders
         on or  purchasers  of any of the  Securities  to a  limited  number  of
         sophisticated  investors  who will  represent  and agree  that they are
         purchasing  for their own account for investment and not with a view to
         the  distribution  or sale of any of such  Securities and (b) to impose
         such other  limitations or conditions in connection  with any such sale
         as the  Administrative  Agent  reasonably  deems  necessary in order to
         comply with applicable  law. The Borrower  covenants and agrees that it
         will execute and deliver such  documents  and take such other action as
         the  Administrative  Agent reasonably deems necessary in order that any
         such sale may be made in compliance  with applicable law. Upon any such
         sale the Administrative  Agent shall have the right to deliver,  assign
         and transfer to the  purchaser  thereof the  Securities  so sold.  Each
         purchaser  at  any  such  sale  shall  hold  the   Securities  so  sold
         absolutely,  free from any claim or right of the Borrower of whatsoever
         kind, including any equity or right of redemption of the Borrower.  The
         Borrower,   to  the  extent   permitted  by  applicable   law,   hereby
         specifically  waives all rights of redemption,  stay or appraisal which
         it has or may have under any law now existing or hereafter enacted.


<PAGE>


                                   ARTICLE VII

                                  Miscellaneous

         Section 7.1  Indemnification.  The Borrower  hereby agrees to indemnify
each  Agent,  each  Lender  and each  Affiliate  thereof  and  their  respective
officers,  directors,   employees,   attorneys,  and  agents  (collectively  the
"Indemnified Parties") from, and hold each of them harmless against, any and all
losses,  liabilities,  claims,  damages,  penalties,  judgments,  disbursements,
costs, and expenses (including  reasonable attorneys' fees) to which any of them
may become subject which directly or indirectly  arise from or relate to (a) the
negotiation, execution, delivery, performance, administration, or enforcement of
this  Agreement  or any  other  Loan  Document,  (b)  any  of  the  transactions
contemplated by this Agreement or any other Loan Document, (c) any breach by the
Borrower of any representation, warranty, covenant, or other agreement contained
in  this  Agreement  or any  other  Loan  Document,  or (d)  any  investigation,
litigation, or other proceeding,  including,  without limitation, any threatened
investigation, litigation, or other proceeding relating to any of the foregoing,
INCLUDING,  WITHOUT  LIMITATION,  THOSE  ARISING  FROM THE SOLE OR  CONTRIBUTORY
NEGLIGENCE OF ANY INDEMNIFIED PARTY.

         Section 7.2 No Waiver;  Cumulative Remedies.  No failure on the part of
any Agent or the Lender to exercise and no delay in exercising, and no course of
dealing with respect to, any right,  power,  or privilege  under this  Agreement
shall operate as a waiver thereof,  nor shall any single or partial  exercise of
any right,  power,  or  privilege  under this  Agreement  preclude  any other or
further  exercise  thereof  or  the  exercise  of any  other  right,  power,  or
privilege. The rights and remedies provided for in this Agreement are cumulative
and not exclusive of any rights and remedies provided by law.

         Section 7.3  Successors and Assigns.  This  Agreement  shall be binding
upon and inure to the benefit of the Borrower, the Agents, the Lenders and their
respective  heirs,  successors,  and  assigns,  except that the Borrower may not
assign any of its rights or obligations  under this Agreement  without the prior
written consent of the Administrative Agent.

         Section 7.4 Amendment;  Entire Agreement.  THIS AGREEMENT  EMBODIES THE
FINAL,  ENTIRE  AGREEMENT  AMONG THE PARTIES  HERETO AND  SUPERSEDES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN  OR  ORAL,  RELATING  TO  THE  SUBJECT  MATTER  HEREOF  AND  MAY  NOT BE
CONTRADICTED OR VARIED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS OR SUBSEQUENT ORAL
AGREEMENTS OR DISCUSSIONS OF THE PARTIES  HERETO.  THERE ARE NO ORAL  AGREEMENTS
AMONG THE PARTIES  HERETO.  The  provisions of this  Agreement may be amended or
waived only by an instrument in writing signed by the parties hereto.

         Section 7.5 Notices. All notices and other communications  provided for
in this Agreement shall be given or made in accordance with Section 13.11 of the
Loan Agreement to the intended  recipient at the "Address for Notices" specified
below its name on the signature pages hereof,  or, as to any party at such other
address  as shall be  designated  by such  party in a notice to the other  party
given in accordance with this Section.

         Section 7.6  Governing  Law.  THIS  AGREEMENT  SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.


<PAGE>


     Section 7.7 Headings. The headings, captions, and arrangements used in this
Agreement are for convenience  only and shall not affect the  interpretation  of
this Agreement.

         Section  7.8   Survival  of   Representations   and   Warranties.   All
representations  and  warranties  made in this  Agreement or in any  certificate
delivered  pursuant  hereto  shall  survive the  execution  and delivery of this
Agreement,  and no  investigation  by any Agent or any Lender  shall  affect the
representations  and  warranties or the right of any Agent or any Lender to rely
upon them.

         Section 7.9 Waiver of Bond. In the event the Administrative Agent seeks
to take  possession  of any or all of the  Collateral by judicial  process,  the
Borrower hereby irrevocably waives any bonds and any surety or security relating
thereto  that  may  be  required  by  applicable  law  as an  incident  to  such
possession,  and waives any demand for possession  prior to the  commencement of
any such suit or action.

         Section 7.10  Severability.  Any provision of this  Agreement  which is
prohibited or unenforceable in any jurisdiction  shall, as to such jurisdiction,
be ineffective to the extent of such  prohibition  or  unenforceability  without
invalidating  the  remaining   provisions  of  this  Agreement,   and  any  such
prohibition  or  unenforceability  in any  jurisdiction  shall not invalidate or
render unenforceable such provision in any other jurisdiction.

         Section 7.11 Construction.  The Borrower and the  Administrative  Agent
acknowledge  that each of them has had the  benefit of legal  counsel of its own
choice and has been afforded an  opportunity  to review this  Agreement with its
legal counsel.

     Section  7.12  Obligations  Absolute.   All  rights  and  remedies  of  the
Administrative  Agent hereunder,  and all obligations of the Borrower hereunder,
shall be absolute and unconditional irrespective of:

     (a) any lack of validity or  enforceability of the Loan Agreement or any of
the other Loan Documents or any other agreement or instrument relating to any of
the foregoing;

                   (b) any change in the time,  manner,  or place of payment of,
         or in any other term of, all or any of the Secured Indebtedness, any or
         all of the  Obligations,  or any  other  amendment  or waiver of or any
         consent to any  departure  from the Loan  Agreement or any of the other
         Loan Documents;

     (c) any exchange,  release,  or  nonperfection  of any  Collateral,  or any
release  or  amendment  or  waiver  of or  consent  to any  departure  from  any
guarantee, for all or any of the Secured Indebtedness; or

                   (d) any other circumstance (other than payment in full of the
         Secured   Indebtedness)  that  might  otherwise  constitute  a  defense
         available to, or a discharge of, the Borrower.


<PAGE>


         Section 7.13 Termination. If all of the Secured Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Borrower and in accordance  with  applicable  provisions of the Loan  Agreement,
promptly execute and deliver to the Borrower a proper  instrument or instruments
acknowledging  the release and termination of the security  interests created by
this Agreement as the Borrower may reasonably  deem necessary or desirable,  and
shall duly assign and deliver to the Borrower  (without recourse and without any
representation  or warranty)  such of the Collateral as may be in the possession
of the  Administrative  Agent  and has not  previously  been  sold or  otherwise
applied pursuant to this Agreement.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.
                            SIGNATURE PAGE TO FOLLOW.


<PAGE>



                           Borrower Security Agreement

         IN WITNESS WHEREOF, the Borrower has duly executed this Agreement as of
the day and year first written above.

                                       BORROWER:
                                       --------

                                       PRIME REFRACTIVE MANAGEMENT, L.L.C.,
                                       a Delaware limited liability company



                                                     By: /s/ Teena E. Belcik
                                                        Teena E. Belcik

                                                        Treasurer

                                                     Address for Notices:

                                               1301 Capital of Texas Highway
                                               Suite C-300
                                               Austin, Texas 78746
                                               Attn: Treasurer
                                               Fax Number:  (512) 328-8510
                                               Telephone Number:  (512) 314-4554


<PAGE>





                                       21

                           Borrower Security Agreement

                                   SCHEDULE 1

                                 MOTOR VEHICLES

None


<PAGE>


                                   SCHEDULE 2

                                   SECURITIES

                                  Pledged Stock

None

                   Pledged Limited Liability Company Interests

         Prime Refractive, L.L.C., a Delaware limited liabilty company
                            - 60% membership interest


<PAGE>


                                   SCHEDULE 3

                             LOCATION OF COLLATERAL

                       Location of Equipment and Inventory

1301 Capital of Texas Highway
Suite C-300

Austin, Travis County, Texas 78746-6550


<PAGE>


                                   SCHEDULE 4

                            JURISDICTIONS FOR FILING

               Jurisdictions for Filing UCC-1 Financing Statements

Texas


<PAGE>


                          BORROWER'S SECURITY AGREEMENT

                           BORROWER SECURITY AGREEMENT

     THIS BORROWER SECURITY AGREEMENT (the "Agreement") dated as of January
31, 2000, is executed by PRIME MEDICAL  SERVICES,  INC., a Delaware  corporation
(the  "Debtor"),  for the benefit of BANK OF AMERICA,  N.A., a national  banking
association  ("B  of  A"),  not  in  its  individual   capacity  but  solely  as
administrative  agent for itself and each of the other Lenders (each, a "Lender"
and  collectively,   the  "Lenders")  as  defined  in  the  Loan  Agreement  (as
hereinafter defined) (in such capacity, together with its successors and assigns
in such capacity, the "Administrative Agent").

                                R E C I T A L S:
                                - - - - - - - -

         A. The Debtor, B of A, as administrative  agent,  BankBoston,  N.A., as
documentation  agent,  and the Lenders have  entered  into that  certain  Fourth
Amended and Restated Loan Agreement  dated January __, 2000, (as the same may be
amended,  restated,  extended,  supplemented  or modified from time to time, the
"Loan Agreement"), pursuant to which the Lenders have agreed to make a revolving
loan to the  Borrower  with  advances  thereunder  not to  exceed  an  aggregate
principal amount of Eighty-Six  Million and 00/100 Dollars  ($86,000,000.00)  at
any one time outstanding.

     B. The Agents and the Lenders have conditioned  their obligations under the
Loan Agreement upon the execution and delivery of this Agreement by the Debtor.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

                                    ARTICLE I

                                   Definitions

         Section 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         Section 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.

     Section  1.3  Additional  Definitions.  As  used  in  this  Agreement,  the
following terms shall have the following meanings:



<PAGE>





                                       16

                          BORROWER'S SECURITY AGREEMENT

                  "Accounts"  means any  "account,"  as such term is  defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor, and, in any
event, shall include,  without  limitation,  each of the following,  whether now
owned or  hereafter  acquired  by the  Debtor:  (a) all  rights of the Debtor to
payment for goods sold or leased or services rendered,  whether or not earned by
performance;  (b) all accounts  receivable of the Debtor;  (c) all rights of the
Debtor to receive any payment of money or other form of  consideration;  (d) all
security pledged, assigned, or granted to or held by the Debtor to secure any of
the foregoing;  (e) all guaranties of, or indemnifications  with respect to, any
of the foregoing;  and (f) all rights of the Debtor as an unpaid seller of goods
or services,  including,  but not limited to, all rights of stoppage in transit,
replevin, reclamation, and resale.

                  "Chattel  Paper"  means any  "chattel  paper," as such term is
defined in Article 9 of the UCC, now owned or hereafter acquired by the Debtor.

                  "Collateral" has the meaning  specified in Section 2.1 of this
Agreement.

                  "Document"  means any  "document,"  as such term is defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor,  including,
without limitation, all documents of title and warehouse receipts of the Debtor.

                  "Equipment"  means any "equipment," as such term is defined in
Article 9 of the UCC, now owned or hereafter  acquired by the Debtor and, in any
event, shall include, without limitation, all machinery, equipment, furnishings,
and  fixtures  now owned or  hereafter  acquired  by the  Debtor and any and all
additions,  substitutions,  and  replacements of any of the foregoing,  wherever
located,  together  with all  attachments,  components,  parts,  equipment,  and
accessories installed thereon or affixed thereto.

                  "General Intangibles" means any "general intangibles," as such
term is defined in Article 9 of the UCC, now owned or hereafter  acquired by the
Debtor  and,  in any  event,  shall  include,  without  limitation,  each of the
following, whether now owned or hereafter acquired by the Debtor: (a) all of the
Debtor's patents, patent applications, patent rights, service marks, trademarks,
trade names,  trade secrets,  intellectual  property,  registrations,  goodwill,
copyrights  (including without limitation,  those copyrights listed on Item A of
Schedule 1 attached hereto), franchises, licenses (including without limitation,
those  copyright  licenses  listed on Item B of  Schedule  1  attached  hereto),
permits,  proprietary information,  customer lists, designs, and inventions; (b)
all of the Debtor's books, records, data, plans, manuals, computer software, and
computer  programs;  (c) all of the Debtor's contract rights,  including without
limitation,  (i) all of the Debtor's  right,  title and interest in that certain
Stock  Purchase  Agreement  dated as of April 26, 1996,  executed by and between
Lithotripters,  Inc., the Debtor, and the sellers named therein;  (d) all of the
Debtor's partnership  interests,  joint venture,  limited liability  company,and
membership  interests  (but only to the  extent  not  otherwise  pledged  to the
Administrative  Agent  pursuant  to a separate  pledge or  security  agreement),
deposit  accounts,  investment  accounts,  and certificates of deposit;  (e) all
rights of the Debtor to payment under letters of credit and similar  agreements;
(f) all tax  refunds  and tax  refund  claims of the  Debtor;  (g) all choses in
action and causes of action of the Debtor (whether arising in contract, tort, or
otherwise and whether or not currently in litigation) and all judgments in favor
of the  Debtor;  (h) all rights and claims of the Debtor  under  warranties  and
indemnities;  and (i) all rights of the Debtor under any insurance,  surety,  or
similar contract or arrangement.

                  "Instrument"  means any  "instrument," as such term is defined
in  Article 9 of the UCC and any note  payable  to Debtor or its order  together
with all collateral  securing such note and all agreements and documents related
thereto or arising therefrom, now owned or hereafter acquired by the Debtor.


<PAGE>


                  "Inventory"  means any "inventory," as such term is defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor, and, in any
event, shall include,  without  limitation,  each of the following,  whether now
owned or  hereafter  acquired  by the Debtor:  (a) all goods and other  personal
property of the Debtor that are held for sale or lease or to be furnished  under
any contract of service; (b) all raw materials, work-in-process, finished goods,
inventory,  supplies, and materials of the Debtor; (c) all wrapping,  packaging,
advertising,  and shipping materials of the Debtor; (d) all goods that have been
returned to,  repossessed  by, or stopped in transit by the Debtor;  and (e) all
Documents evidencing any of the foregoing.

                  "Investment  Property"  means  "investment  property," as such
term is defined in Section 9.115(a)(6) of the Texas Business and Commerce Code.

                  "Motor Vehicle" means all cars,  trucks,  vans and other motor
vehicles  now owned or  hereafter  acquired by the Debtor  which are used by the
Debtor for the transfer of  lithotripters  and  lithotripsy  related  equipment,
including without limitation,  those motor vehicles listed on Schedule 2 hereto,
and  any and all  attachments,  components,  parts,  equipment  and  accessories
installed thereon or affixed thereto.

                  "Proceeds"  means any  "proceeds,"  as such term is defined in
Article 9 of the UCC and, in any event,  shall  include,  but not be limited to,
(a) any and all  proceeds of any  insurance,  indemnity,  warranty,  or guaranty
payable to the Debtor from time to time with  respect to any of the  Collateral,
(b) any and all payments (in any form whatsoever) made or due and payable to the
Debtor  from  time to time in  connection  with any  requisition,  confiscation,
condemnation, seizure, or forfeiture of all or any part of the Collateral by any
Governmental  Authority  (or any  person  acting  under  color  of  Governmental
Authority),  and (c) any and all other amounts from time to time paid or payable
under or in connection with any of the Collateral.

                  "Securities" means all shares of stock of any Person now owned
or hereafter acquired by the Debtor including,  without limitation,  each of the
shares listed on Schedule 3 hereto,  and all dividends,  cash,  stock dividends,
instruments and other investment property from time to time received, receivable
by, or otherwise  distributed to the Debtor for its own account in respect of or
in exchange for any or all of such  shares,  and the  certificates  representing
such shares.

                  "UCC"  means the Uniform  Commercial  Code as in effect in the
State of Texas or, if so required with respect to any  particular  Collateral by
mandatory  provisions of  applicable  law, as in effect in the  jurisdiction  in
which such Collateral is located.

                                   ARTICLE II

                          Security Interest and Pledge

         Section 2.1 Security Interest and Pledge. The Debtor hereby pledges and
grants to the  Administrative  Agent, for the pro rata benefit of the Lenders, a
lien on and security interest in all of the Debtor's right,  title, and interest
in and to the following,  whether now owned or hereafter arising or acquired and
wherever located (collectively, the "Collateral"):

                  (a)      all Accounts;

                  (b)      all Chattel Paper;

                  (c)      all Instruments;

                  (d)      all General Intangibles and all Securities;

                  (e)      all Investment Property;


<PAGE>


                  (f)      all Documents;

                    (g) all Equipment,  including, without limitation, all Motor
               Vehicles;

                  (h) all Inventory;

                    (i) all other  goods and  personal  property  of the  Debtor
               whether tangible or intangible; and

                    (j)  all  Proceeds  and  products  of  any  or  all  of  the
               foregoing.

         Section 2.2  Secured  Indebtedness.  The  Collateral  shall  secure the
following  obligations,   indebtedness,   and  liabilities  (whether  at  stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

                  (a)      the Obligations;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the Collateral, collect the
obligations herein described, and enforce this Agreement; and

     (c) all extensions, renewals, and modifications of any of the foregoing.

         Section  2.3 Debtor  Remains  Liable.  Notwithstanding  anything to the
contrary  contained  herein,  (a) the  Debtor  shall  remain  liable  under  the
contracts  and  agreements  included in the  Collateral  to the extent set forth
therein to perform  all of its duties  and  obligations  thereunder  to the same
extent as if this  Agreement  had not been  executed,  (b) the  exercise  by the
Administrative Agent of any of its rights hereunder shall not release the Debtor
from any of its  duties  or  obligations  under  the  contracts  and  agreements
included in the  Collateral,  and (c) neither the  Administrative  Agent nor any
Lender shall have any  obligation  or liability  under any of the  contracts and
agreements included in the Collateral by reason of this Agreement, nor shall the
Administrative  Agent  or  any  Lender  be  obligated  to  perform  any  of  the
obligations or duties of the Debtor  thereunder or to take any action to collect
or enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         Representations and Warranties

         To induce the Administrative Agent to enter into this Agreement and the
Agents and the Lenders to enter into the Loan Agreement,  the Debtor  represents
and warrants to the Administrative Agent that:


<PAGE>


         Section  3.1  Title.  The Debtor  is,  and with  respect to  Collateral
acquired  after the date  hereof  the Debtor  will be, the legal and  beneficial
owner of the Collateral free and clear of any Lien,  security interest,  pledge,
claim or other  encumbrance  (except for Liens  permitted  by Section 9.2 of the
Loan  Agreement and liens in favor of the  Refractive  Administrative  Agent (as
hereinafter defined)) or, with respect to the Securities, any right or option on
the part of any Person (other than the Lenders) to purchase or otherwise acquire
the Securities or any part thereof,  except for the security  interests  granted
hereunder,  Liens permitted by Section 9.2 of the Loan  Agreement,  and liens in
favor of the Prime  Administrative  Agent (as hereinafter  defined).  Debtor has
granted  subordinate liens and security  interests in the Collateral in favor of
Bank of America, N.A., as Administrative Agent under the Loan Agreement dated as
of the date hereof (the  "Refractive  Loan  Agreement")  among Prime  Refractive
Management, L.L.C., a Delaware limited liability company, Bank of America, N.A.,
as Administrative  Agent (the "Refractive  Administrative  Agent"),  BankBoston,
N.A., as  Documentation  Agent,  and the lenders from time to time party thereto
("Refractive Lenders").

         Section 3.2  Accounts.  Unless the Debtor has given the  Administrative
Agent written  notice to the contrary,  whenever the security  interest  granted
hereunder attaches to an Account, the Debtor shall be deemed to have represented
and  warranted  to the  Administrative  Agent as to each and all of its Accounts
that (a) each Account is genuine and in all respects what it purports to be, (b)
each Account represents the legal,  valid, and binding obligation of the account
debtor  evidencing  indebtedness  unpaid and owed by such account debtor arising
out of the  performance  of labor or services by the Debtor or the sale or lease
of goods by the Debtor,  (c) the amount of each Account  represented as owing is
the correct amount  actually and  unconditionally  owing except for normal trade
discounts  granted in the  ordinary  course of  business,  and (d) no Account is
subject to any offset, counterclaim, or other defense.

         Section 3.3 Rule 144 Securities. With respect to all Collateral that is
Securities  which are subject to Rule 144 under the  Securities  Act of 1933, as
such rule and act are amended at the time in question and any successor in whole
or in part thereto,  (a) the Debtor is the  beneficial and record owner thereof,
free and clear of any Liens or transfer restrictions (other than restrictions on
the amount thereof which may be sold, and the manner in which sales may be made,
imposed by such Rule 144), (b) the Debtor acquired such Securities directly from
the  issuer  thereof  more  than  two (2)  years  prior to the  date  hereof  in
transactions not involving any public offering, (c) the Debtor paid the purchase
price  therefor  in cash more than two (2) years prior to the date  hereof,  (d)
since such date of  acquisition,  the Debtor has not had a short position in, or
any put or option to dispose  of,  any  capital  stock of any issuer  thereof or
Securities convertible into capital stock of any issuer thereof, (e) neither the
Debtor, nor any person or entity, the sales of which are required by Rule 144 to
be  aggregated  with the sales of the Debtor,  has sold any capital stock of any
issuer of such Securities  during the period of six (6) months prior to the date
hereof, other than sales pursuant to an effective  registration  statement under
the Securities Act of 1933, as amended,  and (f) to the Debtor's best knowledge,
each issuer of such Securities has timely filed all reports required to be filed
by it under the Securities Exchange Act of 1934, as amended.

         Section 3.4  Financing  Statements.  No financing  statement,  security
agreement,  or other Lien instrument  covering all or any part of the Collateral
is on file in any public  office,  except as may have been filed in favor of the
Refractive  Administrative  Agent,  any lender under the  Refractive  Agreement,
Administrative  Agent, or any Lender pursuant to this Agreement.  The Debtor has
not within the past five (5) years had a trade name or done  business  under any
name other than its legal name set forth at the beginning of this Agreement.

         Section  3.5  Principal  Place  of  Business.  The  principal  place of
business  and chief  executive  office of the Debtor,  and the office  where the
Debtor  keeps its books and  records,  is located  at the  address of the Debtor
shown on the signature pages of this Agreement.


<PAGE>


         Section 3.6 Location of Collateral.  All Inventory and Equipment of the
Debtor are located at the places specified on Schedule 4 hereto.  The Debtor has
exclusive  possession  and control of its Inventory and  Equipment.  None of the
Inventory or  Equipment  of the Debtor is  evidenced  by a Document  (including,
without limitation,  a negotiable  document of title). All Instruments,  Chattel
Paper, Securities and certificates of title of the Debtor have been delivered to
the Administrative Agent.

         Section  3.7  Perfection.  Upon the filing of Uniform  Commercial  Code
financing  statements in the jurisdictions listed on Schedule 5 attached hereto,
and upon the  Administrative  Agent's  obtaining  possession  of all  Documents,
Instruments,  Chattel Paper, Securities and certificates of title of the Debtor,
and  upon  the  Administrative  Agent's  obtaining  control  of  all  Investment
Property,  the security  interest in favor of the  Administrative  Agent created
herein will constitute a valid and perfected Lien upon and security  interest in
the  Collateral,  subject  to no equal or prior  Lien,  except as  permitted  by
Section 9.2 of the Loan Agreement.

                                   ARTICLE IV

                                    Covenants

         The Debtor  covenants  and agrees  with the  Administrative  Agent that
until the Secured Indebtedness is paid and performed in full and the Commitments
have terminated:

         Section 4.1  Encumbrances.  Except as  permitted  by Section 9.2 of the
Loan Agreement,  the Debtor shall not create,  permit,  or suffer to exist,  and
shall defend the  Collateral  against,  any Lien,  security  interest,  or other
encumbrance  on the  Collateral,  and shall  defend the  Debtor's  rights in the
Collateral and the  Administrative  Agent's security  interest in the Collateral
against the claims and demands of all  Persons.  The Debtor  shall do nothing to
impair the rights of the Administrative Agent in the Collateral.

         Section 4.2 Delivery.  Prior to or concurrently  with the execution and
delivery of this Agreement,  Debtor shall deliver to the Administrative Agent to
acknowledge all certificates  identified on Schedule 4 hereto,  with all Chattel
Paper, Instruments and Documents of the Debtor.

         Section 4.3  Modification of Accounts.  The Debtor shall, in accordance
with prudent  business  practices,  endeavor to collect or cause to be collected
from each  account  debtor  under  its  Accounts,  as and when due,  any and all
amounts  owing under such  Accounts.  Without the prior  written  consent of the
Administrative  Agent,  the Debtor shall not (a) grant any  extension of time on
any  Account  for any payment or grant  extensions  of time for  payments on its
Accounts which cause the aggregate amount of all payments extended by the Debtor
on its Accounts during any fiscal year of the Debtor to exceed $150,000.00,  (b)
compromise,  compound,  or  settle  any of the  Accounts  for less than the full
amount thereof; provided,  however, that the Debtor may compromise,  compound or
settle  any  Account  which is an amount  less  than  $50,000.00,  provided  the
aggregate  amount  compromised,  compounded or settled during any fiscal year of
the Debtor shall not exceed  $150,000.00,  (c) release, in whole or in part, any
Person liable for payment of an Account in excess of  $50,000.00,  (d) allow any
credit  or  discount  for  payment  with  respect  to any  Account  in excess of
$50,000.00,  other  than  trade  discounts  granted  in the  ordinary  course of
business;  provided,  however,  that the  aggregate  amount  of all  credits  or
discounts  granted  during  any  fiscal  year of the  Debtor  shall  not  exceed
$150,000.00,  or (e) release any Lien,  security interest,  or guaranty securing
any Account in excess of $50,000.00.


<PAGE>


         Section  4.4  Disposition  of  Collateral.  The Debtor  shall not sell,
lease,  assign (by operation of law or otherwise),  or otherwise  dispose of, or
grant any option with respect to, the Collateral or any part thereof without the
prior written consent of the  Administrative  Agent,  except the Debtor may sell
Inventory in the ordinary course of business.

         Section  4.5  Distributions.  If the Debtor  shall  become  entitled to
receive or shall receive any stock certificate  (including,  without limitation,
any certificate representing a stock dividend or distribution in connection with
any reclassification,  increase, or reduction of capital or issued in connection
with any  reorganization),  option or  rights,  whether  as an  addition  to, in
substitution  of, or an exchange for any  Collateral  or  otherwise,  the Debtor
agrees to accept the same as the  Administrative  Agent's  agent and to hold the
same in trust for the Administrative  Agent and to deliver the same forthwith to
the  Administrative  Agent in the  exact  form  received,  with the  appropriate
endorsement of the Debtor when necessary and/or appropriate undated stock powers
duly executed in blank, to be held by the Administrative Agent on its own behalf
and on behalf of Refractive  Administrative  Agent as additional  Collateral for
the Secured Indebtedness,  subject to the terms hereof. Any sums paid upon or in
respect of the  Securities  upon the  liquidation  or  dissolution of the issuer
thereof  shall  be paid  over to the  Administrative  Agent  to be held by it as
additional  Collateral for the Secured Indebtedness subject to the terms hereof;
and in case any  distribution  of capital  shall be made on or in respect of the
Securities  or any  property  shall be  distributed  upon or with respect to the
Securities  pursuant to any  recapitalization or reclassification of the capital
of the issuer thereof or pursuant to any  reorganization  of the issuer thereof,
the property so distributed shall be delivered to the Administrative Agent to be
held by it, as additional  Collateral for the Secured  Indebtedness,  subject to
the terms  hereof.  All sums of money and  property  so paid or  distributed  in
respect of the Securities  that are received by the Debtor shall,  until paid or
delivered  to the  Administrative  Agent,  be held by the  Debtor  in  trust  as
additional security for the Secured Indebtedness.

         Section 4.6 Further Assurances. At any time and from time to time, upon
the request of the Administrative  Agent, and at the sole expense of the Debtor,
the Debtor  shall  promptly  execute and deliver all such  further  instruments,
agreements,  and  documents and take such further  action as the  Administrative
Agent may  reasonably  deem  necessary  or desirable to preserve and perfect its
security interest in the Collateral and carry out the provisions and purposes of
this  Agreement.  Without  limiting the generality of the foregoing,  the Debtor
shall:  (a)  execute  and  deliver to the  Administrative  Agent such  financing
statements  as the  Administrative  Agent  may from  time to time  require;  (b)
deliver and pledge to the Administrative Agent all Documents (including, without
limitation,  negotiable  documents of title) evidencing  Inventory or Equipment;
(c) deliver and pledge to the  Administrative  Agent all  certificates  of title
required by the Loan Agreement, Instruments and Chattel Paper of the Debtor with
any necessary  endorsements;  and (d) execute and deliver to the  Administrative
Agent such other documents,  instruments,  and agreements as the  Administrative
Agent  may   reasonably   require  to  perfect  and   maintain   the   validity,
effectiveness,  and priority of the Loan  Documents and the Liens intended to be
created thereby.  The Debtor authorizes the Administrative  Agent to file one or
more financing or continuation statements,  and amendments thereto,  relating to
all or any part of the  Collateral  without the  signature  of the Debtor  where
permitted  by  law.  A  carbon,  photographic,  or  other  reproduction  of this
Agreement or of any  financing  statement  covering the  Collateral  or any part
thereof  shall be  sufficient  as a  financing  statement  and may be filed as a
financing statement.


<PAGE>


         Section 4.7 Risk of Loss;  Insurance.  The Agents and the Lenders shall
not be responsible for any loss or damage to the  Collateral.  The Debtor shall,
at its own expense,  maintain  insurance  with  financially  sound and reputable
insurance  companies  in such  amounts  and  covering  such  risks as is usually
carried  by  corporations  engaged  in similar  businesses  and  owning  similar
properties  in the same general  areas in which the Debtor  operates  consistent
with past  practices  and to the extent  available  on  commercially  reasonable
terms,   provided  that  in  any  event  the  Debtor  will  maintain   workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance,  professional liability insurance and business interruption insurance
reasonably  satisfactory  to the  Administrative  Agent.  Each insurance  policy
covering  Collateral shall name the  Administrative  Agent as loss payee for the
benefit of the Lenders as its  interest  may appear and shall  provide that such
policy will not be canceled or reduced  without  thirty (30) days prior  written
notice to the Administrative Agent.

         Section  4.8   Inspection   Rights.   The  Debtor   shall   permit  the
Administrative  Agent and each Lender and their  respective  representatives  to
examine, inspect, and audit the Collateral and to examine, inspect, and copy the
Debtor's  books  and  records  at  any  reasonable  time  and  as  often  as the
Administrative Agent or any such Lender may desire. The Administrative Agent and
each Lender may at any time and from time to time  contact  account  debtors and
other  obligors  to verify the  existence,  amounts,  and terms of the  Debtor's
Accounts.

         Section 4.9  Corporate  Changes.  The Debtor shall not change its name,
identity,  or corporate  structure  in any manner that might make any  financing
statement filed in connection with this Agreement  seriously  misleading  unless
the Debtor  shall have given the  Administrative  Agent  thirty  (30) days prior
written  notice  thereof  and shall  have  taken all  action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent to make  each  financing
statement  not seriously  misleading.  The Debtor shall not change its principal
place of business, chief executive office, or the place where it keeps its books
and records unless it shall have given the Administrative Agent thirty (30) days
prior written notice thereof and shall have taken all action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent  to cause  its  security
interest in the  Collateral to be perfected  with the priority  required by this
Agreement.

         Section  4.10 Books and  Records;  Information.  The Debtor  shall keep
accurate  and  complete  books and records of the  Collateral  and the  Debtor's
business and financial  condition in accordance with GAAP. The Debtor shall from
time  to  time  at  the  request  of the  Administrative  Agent  deliver  to the
Administrative Agent such information regarding the Collateral and the Debtor as
the Administrative Agent may reasonably request, including,  without limitation,
lists and  descriptions  of the  Collateral  and  evidence of the  identity  and
existence  of the  Collateral.  The Debtor shall mark its records to reflect the
security interest of the Administrative Agent hereunder.

         Section 4.11      Equipment and Inventory.
                           -----------------------

                  (a) The Debtor shall keep the  Equipment  and Inventory at the
         locations  specified  on  Schedule 5 hereto or,  upon  thirty (30) days
         prior written notice to the Administrative  Agent, at such other places
         within  the  United  States of America  where all  action  required  to
         perfect the  Administrative  Agent's security interest in the Equipment
         and Inventory with the priority  required by this Agreement  shall have
         been taken.

               (b) The Debtor shall  maintain  the  Equipment  and  Inventory in
          accordance with Section 8.3 of the Loan Agreement.

         Section 4.12 Warehouse Receipts Non-Negotiable.  The Debtor agrees that
if any  warehouse  receipt or receipt  in the nature of a  warehouse  receipt is
issued in respect of any of the Collateral, such warehouse receipt or receipt in
the nature  thereof shall not be  "negotiable"  (as such term is used in Section
7.104 of the Uniform  Commercial Code as in effect in any relevant  jurisdiction
or under relevant law).


<PAGE>


         Section  4.13 Taxes and  Claims.  The Debtor  shall pay and  discharge,
before the same become  delinquent,  (a) all material  taxes,  assessments,  and
governmental  charges  imposed upon it or upon any of its property,  and (b) all
material  lawful  claims  that,  if unpaid,  might become a Lien upon any of its
property;  provided,  however,  that the Debtor  shall not be required to pay or
discharge  any such  tax,  assessment,  or  governmental  charge  which is being
contested in good faith by proper  proceedings being diligently  pursued and for
which adequate reserves have been established in accordance with GAAP.

         Section  4.14  Compliance  with Laws.  The Debtor  shall  comply in all
material respects with all material applicable laws, rules, regulations, orders,
and decrees of any Governmental Authority or arbitrator.

         Section 4.15 Compliance with Agreements. The Debtor shall comply in all
material respects with all agreements,  contracts, and instruments binding on it
or affecting  its  properties or  businesses,  except where the failure to do so
would not have a material adverse effect on the business,  condition  (financial
or otherwise), operations or properties of the Borrower, any Material Subsidiary
or the Companies (taken as a whole).

         Section  4.16  Notification.  Except as permitted by Section 9.2 of the
Loan Agreement, the Debtor shall promptly notify the Administrative Agent of (a)
any Lien, security interest,  encumbrance, or claim that has attached to or been
made or asserted  against any of the Collateral,  (b) any material change in any
of the Collateral, including, without limitation, any material damage to or loss
of any material portion of the Collateral, (c) the occurrence of any other event
that could have a material  adverse  effect on the  Collateral  or the  security
interest created hereunder, and (d) the occurrence or existence of any Default.

         Section 4.17  Collection of Accounts.  Except as otherwise  provided in
this Section or in any other Loan  Document,  the Debtor shall have the right to
collect  and  receive  payments  on  the  Accounts.   In  connection  with  such
collections,  the Debtor may take (and, at the Administrative Agent's direction,
shall  take)  such  actions  as the  Debtor  or  the  Administrative  Agent  may
reasonably deem necessary or advisable to enforce collection of the Accounts.

         Section 4.18 Additional Securities.  The Debtor shall not consent to or
approve the issuance of any  additional  shares of any class of capital stock of
the issuers of any of the  Securities,  or any securities  convertible  into, or
exchangeable  for, any such shares or any warrants,  options,  rights,  or other
commitments  entitling  any Person to  purchase  or  otherwise  acquire any such
shares.

         Section 4.19 Provide Information.  The Debtor shall fully cooperate, to
the extent reasonably  requested by the Administrative  Agent, in the completion
of any notice,  form,  schedule,  or other document filed by the  Administrative
Agent  on its  own  behalf  or on  behalf  of  the  Debtor,  including,  without
limitation,  any required notice or statement of beneficial  ownership or of the
acquisition of beneficial ownership of the Securities and any notice of proposed
sale of such  Securities  pursuant to Rule 144 as  promulgated by the Securities
and  Exchange  Commission  (the  "SEC")  under the  Securities  Act of 1933,  as
amended.  Without  limiting the  generality of the  foregoing,  the Debtor shall
furnish  to  the  Administrative   Agent  any  and  all  information  which  the
Administrative  Agent may  reasonably  request for  purposes of any such filing,
regarding the Debtor,  the Securities,  and any issuer of any of the Securities,
and the Debtor shall disclose to the  Administrative  Agent all material adverse
information  known by the Debtor with respect to the operations of any issuer of
any of the Securities.


<PAGE>


         Section  4.20  Notification  of Changes in  Beneficial  Ownership.  The
Debtor shall promptly notify the Administrative  Agent of any sale of securities
of any  Subsidiary of the Debtor or by any Person named on the Debtor's Rule 144
questionnaire and shall furnish promptly to the  Administrative  Agent a copy of
any Form 144 filed in respect of any such sale.  In  addition,  if the Debtor or
any other Person named in the Debtor's  Rule 144  questionnaire  shall file with
the  SEC a form  or  other  document  reporting  any  change  in the  beneficial
ownership of the common stock of any Subsidiary of the Debtor,  the Debtor shall
promptly furnish to the Administrative Agent a copy of such form or document.

         Section 4.21  Restriction on Sales after Default.  The Debtor shall not
sell or  suffer  or  permit  any  Person  named  in the  accompanying  Rule  144
questionnaire  to sell  any  shares  of the  same  class  of  securities  as the
Securities at any time after any Event of Default shall have occurred.

         Section  4.22  Fixtures.  For any  Collateral  that is a fixture  or an
accession  which has been  attached  to real  estate or other goods prior to the
perfection of the security  interest  granted in Section 2.1 hereof,  the Debtor
shall furnish to Administrative  Agent, upon demand, a disclaimer of interest in
each such fixture or accession and a consent in writing to the security interest
of Administrative  Agent therein,  signed by all persons and entities having any
interest  in such  fixture or  accession  by virtue of any  interest in the real
estate or other goods to which such fixture or accession has been attached.

         Section 4.23 Notation on Title  Certificates.  If certificates of title
are issued or  outstanding  with  respect to any of the  Collateral,  the Debtor
shall cause the security  interest  granted in Section 2.1 hereof to be properly
noted thereon.

                                    ARTICLE V

                       Rights of the Administrative Agent

         Section  5.1  Power  of  Attorney.   The  Debtor   hereby   irrevocably
constitutes  and  appoints  the  Administrative  Agent and any  officer or agent
thereof,   with   full   power  of   substitution,   as  its  true  and   lawful
attorney-in-fact  with full  irrevocable  power and authority in the name of the
Debtor or in its own name, to take any and all action and to execute any and all
documents and instruments  which the  Administrative  Agent at any time and from
time to time deems reasonably  necessary or desirable to accomplish the purposes
of this  Agreement if an Event of Default shall have occurred and be continuing,
and, without  limiting the generality of the foregoing,  the Debtor hereby gives
the Administrative  Agent the power and right on behalf of the Debtor and in its
own name to do any of the  following  (subject to the rights of the Debtor under
Sections 5.2 and 5.3 hereof),  without notice to or the consent of the Debtor if
an Event of Default shall have occurred and be continuing:

                  (a) to demand, sue for, collect, or receive in the name of the
         Debtor or in its own name, any money or property at any time payable or
         receivable on account of or in exchange for any of the Collateral  and,
         in connection therewith,  endorse checks,  notes, drafts,  acceptances,
         money  orders,  documents of title,  or any other  instruments  for the
         payment of money under the Collateral or any policy of insurance;

               (b) to pay or  discharge  taxes,  Liens,  or  other  encumbrances
          levied or placed on or threatened against the Collateral;

               (c) to notify post office  authorities  to change the address for
          delivery  of  mail  of the  Debtor  to an  address  designated  by the
          Administrative Agent and to receive, open. and subsequently deliver to
          the Debtor mail addressed to the Debtor; and


<PAGE>


                  (d) (i) to direct account debtors and any other parties liable
         for any payment under any of the  Collateral to make payment of any and
         all  monies  due  and  to  become  due   thereunder   directly  to  the
         Administrative  Agent or as the Administrative Agent shall direct; (ii)
         to receive payment of and receipt for any and all monies,  claims,  and
         other  amounts  due and to  become  due at any  time in  respect  of or
         arising out of any Collateral;  (iii) to sign and endorse any invoices,
         freight  or  express  bills,  bills of  lading,  storage  or  warehouse
         receipts, drafts against debtors,  assignments,  proxies, stock powers,
         verifications,  and  notices  in  connection  with  accounts  and other
         documents  relating to the  Collateral;  (vi) to commence and prosecute
         any suit,  action,  or  proceeding  at law or in equity in any court of
         competent  jurisdiction  to collect the  Collateral or any part thereof
         and to enforce  any other  right in respect of any  Collateral;  (v) to
         defend any suit,  action, or proceeding brought against the Debtor with
         respect to any Collateral;  (vi) to settle,  compromise,  or adjust any
         suit,  action,  or  proceeding   described  above  and,  in  connection
         therewith,  to give such  discharges or releases as the  Administrative
         Agent may deem appropriate; (vii) to exchange any of the Collateral for
         other   property  upon  any  merger,   consolidation,   reorganization,
         recapitalization,  or other  readjustment of the issuer thereof and, in
         connection therewith, deposit any of the Collateral with any committee,
         depositary,  transfer agent, registrar, or other designated agency upon
         such terms as the Administrative Agent may determine;  (viii) to add or
         release any guarantor,  indorser,  surety, or other party to any of the
         Collateral;  (ix) to renew,  extend,  or otherwise change the terms and
         conditions of any of the Collateral;  (x) to make, settle,  compromise,
         or  adjust  claims  under  any  insurance  policy  covering  any of the
         Collateral;  (xi) to sell,  transfer,  pledge,  make any agreement with
         respect to or otherwise  deal with any of the  Collateral  as fully and
         completely as though the  Administrative  Agent were the absolute owner
         thereof  for all  purposes,  and to do, at the  Administrative  Agent's
         option and the Debtor's expense, at any time, or from time to time, all
         acts and things  which the  Administrative  Agent  deems  necessary  to
         protect,   preserve,   or   realize   upon  the   Collateral   and  the
         Administrative   Agent's  security  interest  therein;   and  (xii)  to
         complete, execute and file with the SEC one or more notices of proposed
         sale of securities pursuant to Rule 144.

         This power of attorney is a power coupled with an interest and shall be
irrevocable.  Neither the Administrative Agent nor any Lender shall be under any
duty  to  exercise  or  withhold  the  exercise  of any of the  rights,  powers,
privileges,  and options expressly or implicitly  granted to the  Administrative
Agent in this Agreement, and shall not be liable for any failure to do so or any
delay in doing so.  Neither  the  Administrative  Agent nor any Lender  shall be
liable for any act or  omission  or for any error of  judgment or any mistake of
fact or law in its  individual  capacity or in its capacity as  attorney-in-fact
except  acts or  omissions  resulting  from  its  gross  negligence  or  willful
misconduct.  This power of attorney is  conferred  on the  Administrative  Agent
solely to protect,  preserve,  and  realize  upon its  security  interest in the
Collateral. Neither the Administrative Agent nor any Lender shall be responsible
for any decline in the value of the Collateral and shall not be required to take
any steps to preserve rights against prior parties or to protect,  preserve,  or
maintain any security interest or Lien given to secure the Collateral.

         Section 5.2 Voting  Rights.  Unless and until an Event of Default shall
have  occurred and be  continuing,  the Debtor shall be entitled to exercise any
and all voting rights  pertaining to the  Securities or any part thereof for any
purpose not inconsistent with the terms of this Agreement or the Loan Agreement.
The  Administrative  Agent  shall  execute  and  deliver  to the Debtor all such
proxies  and other  instruments  as the Debtor may  reasonably  request  for the
purpose  of  enabling  the Debtor to  exercise  the  voting  rights  which it is
entitled to exercise pursuant to this Section.


<PAGE>


         Section 5.3 Dividends.  Unless and until an Event of Default shall have
occurred and be  continuing,  the Debtor shall be entitled to receive and retain
the dividends on the Securities paid in cash out of earned surplus to the extent
and only to the extent that such dividends are permitted by the Loan Agreement.

         Section 5.4 Setoff,  Property Held by the Lenders.  The  Administrative
Agent and each  Lender  shall  have the right to set off and apply  against  the
Secured Indebtedness,  at any time and without notice to the Debtor, any and all
deposits  (general or special,  time or demand,  provisional  or final) or other
sums at any time  credited  by or owing  from  the  Administrative  Agent or any
Lender to the Debtor  whether or not the  Secured  Indebtedness  is then due. As
additional security for the Secured  Indebtedness,  the Debtor hereby grants the
Administrative  Agent  and  each  Lender  a  security  interest  in  all  money,
instruments,  and other  property  of the  Debtor now or  hereafter  held by the
Administrative Agent or any Lender, including without limitation,  property held
in  safekeeping.  In addition to the  Administrative  Agent's and each  Lender's
right of setoff and as further security for the Secured Indebtedness, the Debtor
hereby  grants to each of them a security  interest in all deposits  (general or
special, time or demand, provisional or final) of the Debtor now or hereafter on
deposit  with or held by any of them and all other sums at any time  credited by
or owing from the any of them to the  Debtor.  The rights  and  remedies  of the
Administrative  Agent and each Lender  hereunder are in addition to other rights
and remedies (including,  without limitation,  other rights of setoff) which any
of them may have.

         Section 5.5  Performance by the Secured Party. If the Debtor shall fail
to  perform  any  covenant  or  agreement  contained  in  this  Agreement,   the
Administrative Agent, may, at the direction of the Required Lenders,  perform or
attempt to perform such  covenant or agreement on behalf of the Debtor.  In such
event, the Debtor shall, at the request of the  Administrative  Agent,  promptly
pay any amount expended by the Administrative  Agent or any Lender in connection
with such  performance  or attempted  performance to the  Administrative  Agent,
together with  interest  thereon at the Default Rate from and including the date
of such  expenditure to but excluding the date such expenditure is paid in full.
Notwithstanding  the  foregoing,   it  is  expressly  agreed  that  neither  the
Administrative  Agent nor any Lender shall have any liability or  responsibility
for the performance of any obligations of the Debtor under this Agreement.

                                   ARTICLE VI

                                     Default

         Section  6.1 Rights  and  Remedies.  If an Event of Default  shall have
occurred and be continuing,  the  Administrative  Agent shall have the following
rights and remedies:


<PAGE>


                  (a) In addition to all other  rights and  remedies  granted to
         the  Administrative  Agent  in  this  Agreement  or in any  other  Loan
         Document or by applicable law, the Administrative  Agent shall have all
         of the rights and remedies of a secured party under the UCC (whether or
         not the UCC applies to the affected  Collateral).  Without limiting the
         generality of the foregoing,  the Administrative  Agent may (i) without
         demand or notice to the Debtor, collect, receive, or take possession of
         the   Collateral   or  any  part  thereof  and  for  that  purpose  the
         Administrative   Agent  may  enter  upon  any  premises  on  which  the
         Collateral is located and remove the Collateral  therefrom or render it
         inoperable,  and/or  (ii)  sell,  lease,  or  otherwise  dispose of the
         Collateral,  or any part  thereof,  in one or more parcels at public or
         private  sale  or  sales,  at the  Administrative  Agent's  offices  or
         elsewhere,  for cash, on credit or for future  delivery,  and upon such
         other  terms  as  the   Administrative   Agent  may  deem  commercially
         reasonable. The Administrative Agent shall have the right at any public
         sale or sales,  and, to the extent  permitted by applicable law, at any
         private sale or sales,  to bid and become a purchaser of the Collateral
         or any part  thereof free of any right or equity of  redemption  on the
         part of the  Debtor,  which  right or  equity of  redemption  is hereby
         expressly  waived and  released by the Debtor.  Upon the request of the
         Administrative Agent, the Debtor shall assemble the Collateral and make
         it available to the Administrative Agent at any place designated by the
         Administrative  Agent that is  reasonably  convenient to the Debtor and
         the  Administrative  Agent.  The Debtor agrees that the  Administrative
         Agent shall not be  obligated  to give more than five (5) days  written
         notice of the time and place of any  public  sale or of the time  after
         which  any  private  sale may take  place and that  such  notice  shall
         constitute  reasonable notice of such matters. The Administrative Agent
         shall  not be  obligated  to make  any sale of  Collateral  if it shall
         determine  not to do so,  regardless of the fact that notice of sale of
         Collateral may have been given. The  Administrative  Agent may, without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place fixed for sale, and such sale may,  without  further  notice,  be
         made at the time and  place to  which  the same was so  adjourned.  The
         Debtor shall be liable for all expenses of retaking, holding, preparing
         for sale, or the like, and all attorneys' fees, legal expenses, and all
         other costs and expenses  incurred by the  Administrative  Agent or any
         Lender in connection  with the  collection of the Secured  Indebtedness
         and the  enforcement  of the  Administrative  Agent's and the  Lender's
         rights under this  Agreement.  The Debtor  shall remain  liable for any
         deficiency  if the  Proceeds  of any sale or other  disposition  of the
         Collateral are  insufficient  to pay the Secured  Indebtedness in full.
         The  Administrative  Agent and the  Lenders  may  apply the  Collateral
         against  the  Secured  Indebtedness  in such  order  and  manner as the
         Administrative  Agent and the Lenders may elect.  The Debtor waives all
         rights of  marshaling,  valuation,  and  appraisal  in  respect  of the
         Collateral.

                  (b)  The  Administrative  Agent  may  cause  any or all of the
         Collateral  held  by  it  to  be  transferred  into  the  name  of  the
         Administrative Agent or the name or names of the Administrative Agent's
         nominee or nominees.

                  (c) The  Administrative  Agent  may  exercise  or  cause to be
         exercised  all voting,  consensual  and other  powers of  ownership  in
         respect  of  the  Collateral  and  the  Debtor  shall  deliver  to  the
         Administrative   Agent,  if  requested  by  the  Administrative  Agent,
         irrevocable proxies with respect to the Securities in form satisfactory
         to the Administrative Agent.

                  (d) The Administrative  Agent may collect or receive all money
         or  property  at any time  payable  or  receivable  on account of or in
         exchange for any of the Collateral, but shall be under no obligation to
         do so.

                  (e) On any sale of the Collateral, the Administrative Agent is
         hereby  authorized to comply with any  limitation or  restriction  with
         which  compliance  is  necessary,  in the  view  of the  Administrative
         Agent's  counsel,  in order to avoid any violation of applicable law or
         in order to obtain any required approval of the purchaser or purchasers
         by any applicable Governmental Authority.


<PAGE>


                  (f) The Debtor agrees that,  because of the  Securities Act of
         1933,  as  amended,  or any other  laws or  regulations,  and for other
         reasons,   there  may  be  legal  and/or   practical   restrictions  or
         limitations  affecting  the  Administrative  Agent in any  attempts  to
         dispose of certain  portions of the Securities and for the  enforcement
         of their rights. For these reasons,  the Administrative Agent is hereby
         authorized by the Debtor,  but not  obligated,  upon the occurrence and
         during the continuation of an Event of Default, to sell all or any part
         of the Securities at private sale,  subject to investment  letter or in
         any other  manner  which will not require the  Securities,  or any part
         thereof,  to be  registered in accordance  with the  Securities  Act of
         1933, as amended, or the rules and regulations  promulgated thereunder,
         or any other laws or regulations, at a reasonable price at such private
         sale or other  distribution in the manner  mentioned  above. The Debtor
         understands  that  the  Administrative  Agent  may  in  its  discretion
         approach a limited number of potential purchasers and that a sale under
         such  circumstances may yield a lower price for the Securities,  or any
         part or party  thereof,  than would  otherwise  be  obtainable  if such
         collateral  were  either  afforded  to a  larger  number  or  potential
         purchasers, or registered or sold in the open market. The Debtor agrees
         that  such  private  sale  shall  be  deemed  to  have  been  made in a
         commercially  reasonable manner, and that the Administrative  Agent has
         no  obligation  to delay  sale of any  Securities  to permit the issuer
         thereof to register it for public sale under any applicable  federal or
         state  securities  laws. The  Administrative  Agent is  authorized,  in
         connection with any such sale (a) to restrict the  prospective  bidders
         on or  purchasers  of any of the  Securities  to a  limited  number  of
         sophisticated  investors  who will  represent  and agree  that they are
         purchasing  for their own account for investment and not with a view to
         the  distribution  or sale of any of such  Securities and (b) to impose
         such other  limitations or conditions in connection  with any such sale
         as the  Administrative  Agent  reasonably  deems  necessary in order to
         comply with  applicable  law. The Debtor  covenants  and agrees that it
         will execute and deliver such  documents  and take such other action as
         the  Administrative  Agent reasonably deems necessary in order that any
         such sale may be made in compliance  with applicable law. Upon any such
         sale the Administrative  Agent shall have the right to deliver,  assign
         and transfer to the  purchaser  thereof the  Securities  so sold.  Each
         purchaser  at  any  such  sale  shall  hold  the   Securities  so  sold
         absolutely,  free from any claim or right of the  Debtor of  whatsoever
         kind,  including any equity or right of  redemption of the Debtor.  The
         Debtor, to the extent permitted by applicable law, hereby  specifically
         waives all rights of redemption,  stay or appraisal which it has or may
         have under any law now existing or hereafter enacted.

                                   ARTICLE VII

                                  Miscellaneous

         Section 7.1 Indemnification. The Debtor hereby agrees to indemnify each
Agent,  each Lender and each Affiliate  thereof and their  respective  officers,
directors,  employees,  attorneys,  and agents  (collectively  the  "Indemnified
Parties")  from,  and hold each of them  harmless  against,  any and all losses,
liabilities,  claims, damages, penalties, judgments,  disbursements,  costs, and
expenses (including  reasonable attorneys' fees) to which any of them may become
subject  which  directly  or  indirectly   arise  from  or  relate  to  (a)  the
negotiation, execution, delivery, performance, administration, or enforcement of
this  Agreement  or any  other  Loan  Document,  (b)  any  of  the  transactions
contemplated by this Agreement or any other Loan Document, (c) any breach by the
Debtor of any representation,  warranty,  covenant, or other agreement contained
in  this  Agreement  or any  other  Loan  Document,  or (d)  any  investigation,
litigation, or other proceeding,  including,  without limitation, any threatened
investigation, litigation, or other proceeding relating to any of the foregoing,
INCLUDING,  WITHOUT  LIMITATION,  THOSE  ARISING  FROM THE SOLE OR  CONTRIBUTORY
NEGLIGENCE OF ANY INDEMNIFIED PARTY.

         Section 7.2 No Waiver;  Cumulative Remedies.  No failure on the part of
any Agent or the Lender to exercise and no delay in exercising, and no course of
dealing with respect to, any right,  power,  or privilege  under this  Agreement
shall operate as a waiver thereof,  nor shall any single or partial  exercise of
any right,  power,  or  privilege  under this  Agreement  preclude  any other or
further  exercise  thereof  or  the  exercise  of any  other  right,  power,  or
privilege. The rights and remedies provided for in this Agreement are cumulative
and not exclusive of any rights and remedies provided by law.


<PAGE>


         Section 7.3  Successors and Assigns.  This  Agreement  shall be binding
upon and inure to the benefit of the Debtor,  the Agents,  the Lenders and their
respective heirs, successors, and assigns, except that the Debtor may not assign
any of its rights or obligations  under this Agreement without the prior written
consent of the Administrative Agent.

         Section 7.4 Amendment;  Entire Agreement.  THIS AGREEMENT  EMBODIES THE
FINAL,  ENTIRE  AGREEMENT  AMONG THE PARTIES  HERETO AND  SUPERSEDES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN  OR  ORAL,  RELATING  TO  THE  SUBJECT  MATTER  HEREOF  AND  MAY  NOT BE
CONTRADICTED OR VARIED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS OR SUBSEQUENT ORAL
AGREEMENTS OR DISCUSSIONS OF THE PARTIES  HERETO.  THERE ARE NO ORAL  AGREEMENTS
AMONG THE PARTIES  HERETO.  The  provisions of this  Agreement may be amended or
waived only by an instrument in writing signed by the parties hereto.

         Section 7.5 Notices. All notices and other communications  provided for
in this Agreement shall be given or made in accordance with Section 13.11 of the
Loan Agreement to the intended  recipient at the "Address for Notices" specified
below its name on the signature pages hereof,  or, as to any party at such other
address  as shall be  designated  by such  party in a notice to the other  party
given in accordance with this Section.

         Section 7.6  Governing  Law.  THIS  AGREEMENT  SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.

     Section 7.7 Headings. The headings, captions, and arrangements used in this
Agreement are for convenience  only and shall not affect the  interpretation  of
this Agreement.

         Section  7.8   Survival  of   Representations   and   Warranties.   All
representations  and  warranties  made in this  Agreement or in any  certificate
delivered  pursuant  hereto  shall  survive the  execution  and delivery of this
Agreement,  and no  investigation  by any Agent or any Lender  shall  affect the
representations  and  warranties or the right of any Agent or any Lender to rely
upon them.

         Section 7.9 Waiver of Bond. In the event the Administrative Agent seeks
to take  possession  of any or all of the  Collateral by judicial  process,  the
Debtor hereby  irrevocably  waives any bonds and any surety or security relating
thereto  that  may  be  required  by  applicable  law  as an  incident  to  such
possession,  and waives any demand for possession  prior to the  commencement of
any such suit or action.

         Section 7.10  Severability.  Any provision of this  Agreement  which is
prohibited or unenforceable in any jurisdiction  shall, as to such jurisdiction,
be ineffective to the extent of such  prohibition  or  unenforceability  without
invalidating  the  remaining   provisions  of  this  Agreement,   and  any  such
prohibition  or  unenforceability  in any  jurisdiction  shall not invalidate or
render unenforceable such provision in any other jurisdiction.

         Section  7.11  Construction.  The Debtor and the  Administrative  Agent
acknowledge  that each of them has had the  benefit of legal  counsel of its own
choice and has been afforded an  opportunity  to review this  Agreement with its
legal counsel.


<PAGE>


     Section  7.12  Obligations  Absolute.   All  rights  and  remedies  of  the
Administrative  Agent  hereunder,  and all obligations of the Debtor  hereunder,
shall be absolute and unconditional irrespective of:

               (a) any lack of validity or  enforceability of the Loan Agreement
          or any  of  the  other  Loan  Documents  or  any  other  agreement  or
          instrument relating to any of the foregoing;

                   (b) any change in the time,  manner,  or place of payment of,
         or in any other term of, all or any of the Secured Indebtedness, any or
         all of the  Obligations,  or any  other  amendment  or waiver of or any
         consent to any  departure  from the Loan  Agreement or any of the other
         Loan Documents;

               (c) any exchange, release, or nonperfection of any Collateral, or
          any release or amendment or waiver of or consent to any departure from
          any guarantee, for all or any of the Secured Indebtedness; or

                   (d) any other circumstance (other than payment in full of the
         Secured   Indebtedness)  that  might  otherwise  constitute  a  defense
         available to, or a discharge of, the Debtor.

         Section 7.13 Renewal.  Debtor acknowledges that this Agreement has been
given  in  amendment,   renewal,   restatement  and   confirmation  of  Debtor's
obligations,  covenants,  and  agreements  contained in the  Guarantor  Security
Agreement previously executed by Debtor in favor of Administrative Agent and the
Lenders, dated April 26, 1996, as amended,  confirmed,  and renewed from time to
time (the "Previous Agreement"). Debtor further confirms and agrees that neither
the  execution  of the  Loan  Agreement  or any  other  Loan  Document,  nor the
consummation of the transactions  described therein, shall in any way affect the
liens under the Previous  Agreement,  and the  obligations,  liens, and security
interests  evidenced by the Previous Agreement continue in full force and effect
as modified, amended, and restated by the terms contained herein.

         Section 7.14 Termination. If all of the Secured Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Debtor and in  accordance  with  applicable  provisions  of the Loan  Agreement,
promptly  execute and deliver to the Debtor a proper  instrument or  instruments
acknowledging  the release and termination of the security  interests created by
this  Agreement as the Debtor may reasonably  deem  necessary or desirable,  and
shall duly assign and deliver to the Debtor  (without  recourse  and without any
representation  or warranty)  such of the Collateral as may be in the possession
of the  Administrative  Agent  and has not  previously  been  sold or  otherwise
applied pursuant to this Agreement.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGE TO FOLLOW.


<PAGE>



                          BORROWER'S SECURITY AGREEMENT

         IN WITNESS  WHEREOF,  the Debtor has duly executed this Agreement as of
the day and year first written above.

                                     DEBTOR:

                                               PRIME MEDICAL SERVICES, INC.,
                                                 a Delaware corporation

                                               By: /s/ Teena E. Belcik
                                                          Teena E. Belcik
                                                          Treasurer

                                               Address for Notices:

                                               1301 Capital of Texas Highway
                                               Suite C-300
                                               Austin, Texas 78746
                                               Attn: Treasurer
                                               Fax Number:  (512) 328-8510
                                               Telephone Number:  (512) 314-4554








<PAGE>





                                       22

                          BORROWER'S SECURITY AGREEMENT

                                   SCHEDULE 1

Item A

         Intellectual Property
                           None

Item B

         Copyrights
                  None


<PAGE>


                                   SCHEDULE 2

                                 MOTOR VEHICLES

None.


<PAGE>


                                   SCHEDULE 3

                                   SECURITIES

                             SHARES OF SUBSIDIARIES

                                  Pledged Stock

Prime Medical Operating, Inc., a Delaware         - 1,000 shares of common stock
         corporation
Ohio Litho, Inc., a Delaware corporation          - 1,000 shares of common stock
R.R. Litho, Inc., a Delaware corporation          - 1,000 shares of common stock
Lithotripters, Inc., a North Carolina corporation -40,000 shares of common stock
FastStart, Inc., a North Carolina corporation     -10,000 shares of common stock
National Lithotripters Association, Inc., a North

         Carolina corporation                         100 shares of common stock
Prostatherapies, Inc., a Delaware corporation         100 shares of common stock
MedTech Investments, Inc., a North Carolina
         corporation                                5,375 shares of common stock


                           SHARES OF NON-SUBSIDIARIES

                                  Pledged Stock

American Physicians Service Group, Inc.           -50,000 shares of Common Stock




<PAGE>


                                   SCHEDULE 4

                             LOCATION OF COLLATERAL

                       Location of Equipment and Inventory

1301 Capital of Texas Highway
Suite C-300

Austin, Travis County, Texas 78746-6550


<PAGE>


                                   SCHEDULE 5

                            JURISDICTIONS FOR FILING

               Jurisdictions for Filing UCC-1 Financing Statements

Texas




                          Guarantor Security Agreement

                          GUARANTOR SECURITY AGREEMENT

         THIS GUARANTOR SECURITY AGREEMENT (the "Agreement") dated as of January
31, 2000, is executed by PRIME PRACTICE MANAGEMENT, INC., a New York corporation
(the  "Debtor"),  for the benefit of BANK OF AMERICA,  N.A., a national  banking
association  ("B  of  A"),  not  in  its  individual   capacity  but  solely  as
administrative  agent for itself and each of the other Lenders (each, a "Lender"
and  collectively,   the  "Lenders")  as  defined  in  the  Loan  Agreement  (as
hereinafter defined) (in such capacity, together with its successors and assigns
in such capacity, the "Administrative Agent").

                                R E C I T A L S:
                                 - - - - - - - -

         A. Prime Refractive  Management,  L.L.C., a Delaware limited  liability
company (the "Borrower"), B of A, as administrative agent, BankBoston,  N.A., as
documentation  agent,  and the  Lenders  have  entered  into that  certain  Loan
Agreement  dated  January  31,  2000,  (as the  same may be  amended,  restated,
extended,  supplemented  or modified from time to time,  the "Loan  Agreement"),
pursuant to which the Lenders have agreed to make an advancing  term loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Fourteen Million and 00/100 Dollars ($14,000,000.00).

         B. The  Debtor,  together  with other  guarantors,  has  executed  that
certain  Guaranty  Agreement of even date  herewith (as the same may be amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
the Debtor has  guaranteed to the Agents (as defined in the Loan  Agreement) and
the Lenders the full and complete payment and performance of the Obligations (as
defined in the Loan Agreement).

     C. The Agents and the Lenders have conditioned  their obligations under the
Loan Agreement upon the execution and delivery of this Agreement by the Debtor.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

                                    ARTICLE I

                                   Definitions

         Section 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         Section 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.

     Section  1.3  Additional  Definitions.  As  used  in  this  Agreement,  the
following terms shall have the following meanings:



<PAGE>





                                       13

                          Guarantor Security Agreement

                  "Accounts"  means any  "account,"  as such term is  defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor, and, in any
event, shall include,  without  limitation,  each of the following,  whether now
owned or  hereafter  acquired  by the  Debtor:  (a) all  rights of the Debtor to
payment for goods sold or leased or services rendered,  whether or not earned by
performance;  (b) all accounts  receivable of the Debtor;  (c) all rights of the
Debtor to receive any payment of money or other form of  consideration;  (d) all
security pledged, assigned, or granted to or held by the Debtor to secure any of
the foregoing;  (e) all guaranties of, or indemnifications  with respect to, any
of the foregoing;  and (f) all rights of the Debtor as an unpaid seller of goods
or services,  including,  but not limited to, all rights of stoppage in transit,
replevin, reclamation, and resale.

                  "Chattel  Paper"  means any  "chattel  paper," as such term is
defined in Article 9 of the UCC, now owned or hereafter acquired by the Debtor.

                  "Collateral" has the meaning  specified in Section 2.1 of this
Agreement.

                  "Document"  means any  "document,"  as such term is defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor,  including,
without limitation, all documents of title and warehouse receipts of the Debtor.

                  "Equipment"  means any "equipment," as such term is defined in
Article 9 of the UCC, now owned or hereafter  acquired by the Debtor and, in any
event, shall include, without limitation, all machinery, equipment, furnishings,
and  fixtures  now owned or  hereafter  acquired  by the  Debtor and any and all
additions,  substitutions,  and  replacements of any of the foregoing,  wherever
located,  together  with all  attachments,  components,  parts,  equipment,  and
accessories installed thereon or affixed thereto.

                  "General Intangibles" means any "general intangibles," as such
term is defined in Article 9 of the UCC, now owned or hereafter  acquired by the
Debtor  and,  in any  event,  shall  include,  without  limitation,  each of the
following, whether now owned or hereafter acquired by the Debtor: (a) all of the
Debtor's patents, patent applications, patent rights, service marks, trademarks,
trade names,  trade secrets,  intellectual  property,  registrations,  goodwill,
copyrights,  franchises,  licenses, permits,  proprietary information,  customer
lists, designs, and inventions;  (b) all of the Debtor's books,  records,  data,
plans,  manuals,  computer  software,  and  computer  programs;  (c)  all of the
Debtor's  contract  rights,   partnership  interests,   joint  venture,  limited
liability  company,  and  membership  interests  (but  only  to the  extent  not
otherwise pledged to the  Administrative  Agent pursuant to a separate pledge or
security agreement),  deposit accounts, investment accounts, and certificates of
deposit;  (d) all rights of the Debtor to  payment  under  letters of credit and
similar agreements; (e) all tax refunds and tax refund claims of the Debtor; (g)
all  choses in action and  causes of action of the  Debtor  (whether  arising in
contract, tort, or otherwise and whether or not currently in litigation) and all
judgments in favor of the Debtor;  (g) all rights and claims of the Debtor under
warranties  and  indemnities;  and  (h)  all  rights  of the  Debtor  under  any
insurance, surety, or similar contract or arrangement.

                  "Instrument"  means any  "instrument," as such term is defined
in  Article 9 of the UCC and any note  payable  to Debtor or its order  together
with all collateral  securing such note and all agreements and documents related
thereto or arising therefrom, now owned or hereafter acquired by the Debtor.

                  "Inventory"  means any "inventory," as such term is defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor, and, in any
event, shall include,  without  limitation,  each of the following,  whether now
owned or  hereafter  acquired  by the Debtor:  (a) all goods and other  personal
property of the Debtor that are held for sale or lease or to be furnished  under
any contract of service; (b) all raw materials, work-in-process, finished goods,
inventory,  supplies, and materials of the Debtor; (c) all wrapping,  packaging,
advertising,  and shipping materials of the Debtor; (d) all goods that have been
returned to,  repossessed  by, or stopped in transit by the Debtor;  and (e) all
Documents evidencing any of the foregoing.

                  "Investment  Property"  means  "investment  property," as such
term is defined in Section 9.115(a)(6) of the Texas Business and Commerce Code.


<PAGE>


                  "Motor Vehicle" means all cars,  trucks,  vans and other motor
vehicles  now owned or  hereafter  acquired by the Debtor  which are used by the
Debtor for the transfer of  lithotripters  and  lithotripsy  related  equipment,
including without limitation,  those motor vehicles listed on Schedule 1 hereto,
and  any and all  attachments,  components,  parts,  equipment  and  accessories
installed thereon or affixed thereto.

                  "Proceeds"  means any  "proceeds,"  as such term is defined in
Article 9 of the UCC and, in any event,  shall  include,  but not be limited to,
(a) any and all  proceeds of any  insurance,  indemnity,  warranty,  or guaranty
payable to the Debtor from time to time with  respect to any of the  Collateral,
(b) any and all payments (in any form whatsoever) made or due and payable to the
Debtor  from  time to time in  connection  with any  requisition,  confiscation,
condemnation, seizure, or forfeiture of all or any part of the Collateral by any
Governmental  Authority  (or any  person  acting  under  color  of  Governmental
Authority),  and (c) any and all other amounts from time to time paid or payable
under or in connection with any of the Collateral.

                  "Securities" means all shares of stock of any Person now owned
or hereafter acquired by the Debtor including,  without limitation,  each of the
shares listed on Schedule 2 hereto,  and all dividends,  cash,  stock dividends,
instruments and other investment property from time to time received, receivable
by, or otherwise  distributed to the Debtor for its own account in respect of or
in exchange for any or all of such  shares,  and the  certificates  representing
such shares.

                  "UCC"  means the Uniform  Commercial  Code as in effect in the
State of Texas or, if so required with respect to any  particular  Collateral by
mandatory  provisions of  applicable  law, as in effect in the  jurisdiction  in
which such Collateral is located.

                                   ARTICLE II

                          Security Interest and Pledge

         Section 2.1 Security Interest and Pledge. The Debtor hereby pledges and
grants to the  Administrative  Agent, for the pro rata benefit of the Lenders, a
lien on and security interest in all of the Debtor's right,  title, and interest
in and to the following,  whether now owned or hereafter arising or acquired and
wherever located (collectively, the "Collateral"):

                  (a)      all Accounts;

                  (b)      all Chattel Paper;

                  (c)      all Instruments;

                  (d)      all General Intangibles and all Securities;

                  (e)      all Investment Property;

                  (f)      all Documents;

     (g) all Equipment, including, without limitation, all Motor Vehicles;

                  (h)      all Inventory;

                    (i) all other  goods and  personal  property  of the  Debtor
                    whether tangible or intangible; and

                    (j)  all  Proceeds  and  products  of  any  or  all  of  the
                    foregoing.


<PAGE>


         Section 2.2  Secured  Indebtedness.  The  Collateral  shall  secure the
following  obligations,   indebtedness,   and  liabilities  (whether  at  stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

     (a) the Obligations and the  obligations,  liabilities and  indebtedness of
the Debtor to the Agents and the Lenders under the Guaranty;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the Collateral, collect the
obligations herein described, and enforce this Agreement; and

     (c) all extensions, renewals, and modifications of any of the foregoing.

         Section  2.3 Debtor  Remains  Liable.  Notwithstanding  anything to the
contrary  contained  herein,  (a) the  Debtor  shall  remain  liable  under  the
contracts  and  agreements  included in the  Collateral  to the extent set forth
therein to perform  all of its duties  and  obligations  thereunder  to the same
extent as if this  Agreement  had not been  executed,  (b) the  exercise  by the
Administrative Agent of any of its rights hereunder shall not release the Debtor
from any of its  duties  or  obligations  under  the  contracts  and  agreements
included in the  Collateral,  and (c) neither the  Administrative  Agent nor any
Lender shall have any  obligation  or liability  under any of the  contracts and
agreements included in the Collateral by reason of this Agreement, nor shall the
Administrative  Agent  or  any  Lender  be  obligated  to  perform  any  of  the
obligations or duties of the Debtor  thereunder or to take any action to collect
or enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         Representations and Warranties

         To induce the Administrative Agent to enter into this Agreement and the
Agents and the Lenders to enter into the Loan Agreement,  the Debtor  represents
and warrants to the Administrative Agent that:

         Section  3.1  Corporate  Existence.  The Debtor:  (a) is a  corporation
validly existing, and in good standing under the laws of the jurisdiction of its
incorporation;  (b) has all requisite  corporate  power and authority to own its
assets and carry on its  business as now being or as  proposed to be  conducted;
and (c) is qualified to do business in all  jurisdictions in which the nature of
its business makes such qualification  necessary and where failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Debtor.  The  Debtor  has  the
corporate power and authority to execute,  deliver,  and perform its obligations
under this Agreement and the other Loan Documents to which it is or may become a
party.

         Section 3.2 Corporate Action; No Breach. The execution,  delivery,  and
performance  by the Debtor of this  Agreement  and the other Loan  Documents  to
which the  Debtor is or may  become a party  and  compliance  with the terms and
provisions  hereof  and  thereof  have been  duly  authorized  by all  requisite
corporate  action on the part of the Debtor and do not and will not (a)  violate
or conflict with, or result in a breach of, or require any consent under (i) the
articles of incorporation or bylaws of the Debtor,  (ii) any material applicable
law, rule, or regulation or any material order, writ,  injunction,  or decree of
any  Governmental  Authority or arbitrator,  or (iii) any material  agreement or
instrument  to which the Debtor is a party or by which it or any of its property
is bound or subject,  or (b)  constitute a material  default  under any material
agreement or  instrument,  or result in the creation or  imposition  of any Lien
(except as provided in Section 2.1 hereof) upon any of the revenues or assets of
the Debtor.


<PAGE>


         Section 3.3 Approvals.  No authorization,  approval, or consent of, and
no filing or registration with, any Governmental  Authority or third party is or
will be necessary for the execution,  delivery,  or performance by the Debtor of
this Agreement and the other Loan Documents to which the Debtor is or may become
a party or the validity or enforceability thereof.

         Section 3.4 Enforceability.  This Agreement constitutes,  and the other
Loan Documents to which the Debtor is party,  when delivered,  shall  constitute
legal,  valid, and binding  obligations of the Debtor,  enforceable  against the
Debtor  in  accordance  with  their  respective  terms,  except  as  limited  by
bankruptcy,  insolvency,  or other laws of general  application  relating to the
enforcement of creditors' rights.

         Section  3.5  Title.  The Debtor  is,  and with  respect to  Collateral
acquired  after the date  hereof  the Debtor  will be, the legal and  beneficial
owner of the Collateral free and clear of any Lien,  security interest,  pledge,
claim or other  encumbrance  (except for Liens  permitted  by Section 9.2 of the
Loan  Agreement  and  liens in  favor  of the  Prime  Administrative  Agent  (as
hereinafter defined)) or, with respect to the Securities, any right or option on
the part of any Person (other than the Lenders) to purchase or otherwise acquire
the Securities or any part thereof,  except for the security  interests  granted
hereunder,  Liens permitted by Section 9.2 of the Loan  Agreement,  and liens in
favor of the Prime Administrative Agent (as hereinafter defined).  The liens and
security  interests  granted  herein are  subject and  subordinate  to the liens
granted in favor of Bank of America,  N.A.,  as  Administrative  Agent under the
Fourth  Amended and  Restated  Loan  Agreement  dated as of the date hereof (the
"Prime Loan  Agreement")  among Prime Medical  Services,  Inc., Bank of America,
N.A., as Administrative Agent (the "Prime  Administrative  Agent"),  BankBoston,
N.A., as Documentation Agent, and the lenders from time to time party thereto.

         Section 3.6  Accounts.  Unless the Debtor has given the  Administrative
Agent written  notice to the contrary,  whenever the security  interest  granted
hereunder attaches to an Account, the Debtor shall be deemed to have represented
and  warranted  to the  Administrative  Agent as to each and all of its Accounts
that (a) each Account is genuine and in all respects what it purports to be, (b)
each Account represents the legal,  valid, and binding obligation of the account
debtor  evidencing  indebtedness  unpaid and owed by such account debtor arising
out of the  performance  of labor or services by the Debtor or the sale or lease
of goods by the Debtor,  (c) the amount of each Account  represented as owing is
the correct amount  actually and  unconditionally  owing except for normal trade
discounts  granted in the  ordinary  course of  business,  and (d) no Account is
subject to any offset, counterclaim, or other defense.

         Section 3.7 Rule 144 Securities. With respect to all Collateral that is
Securities  which are subject to Rule 144 under the  Securities  Act of 1933, as
such rule and act are amended at the time in question and any successor in whole
or in part thereto,  (a) the Debtor is the  beneficial and record owner thereof,
free and clear of any Liens or transfer restrictions (other than restrictions on
the amount thereof which may be sold, and the manner in which sales may be made,
imposed by such Rule 144), (b) the Debtor acquired such Securities directly from
the  issuer  thereof  more  than  two (2)  years  prior to the  date  hereof  in
transactions not involving any public offering, (c) the Debtor paid the purchase
price  therefor  in cash more than two (2) years prior to the date  hereof,  (d)
since such date of  acquisition,  the Debtor has not had a short position in, or
any put or option to dispose  of,  any  capital  stock of any issuer  thereof or
Securities convertible into capital stock of any issuer thereof, (e) neither the
Debtor, nor any person or entity, the sales of which are required by Rule 144 to
be  aggregated  with the sales of the Debtor,  has sold any capital stock of any
issuer of such Securities  during the period of six (6) months prior to the date
hereof, other than sales pursuant to an effective  registration  statement under
the Securities Act of 1933, as amended,  and (f) to the Debtor's best knowledge,
each issuer of such Securities has timely filed all reports required to be filed
by it under the Securities Exchange Act of 1934, as amended.


<PAGE>


         Section 3.8  Financing  Statements.  No financing  statement,  security
agreement,  or other Lien instrument  covering all or any part of the Collateral
is on file in any public  office,  except as may have been filed in favor of the
Prime Administrative Agent, any lender under the Prime Agreement, Administrative
Agent, or any Lender  pursuant to this Agreement.  The Debtor has not within the
past five (5) years had a trade name or done business  under any name other than
its legal name set forth at the beginning of this Agreement.

         Section  3.9  Principal  Place  of  Business.  The  principal  place of
business  and chief  executive  office of the Debtor,  and the office  where the
Debtor  keeps its books and  records,  is located  at the  address of the Debtor
shown on the signature pages of this Agreement.

         Section 3.10 Location of Collateral. All Inventory and Equipment of the
Debtor are located at the places specified on Schedule 3 hereto.  The Debtor has
exclusive  possession  and control of its Inventory and  Equipment.  None of the
Inventory or  Equipment  of the Debtor is  evidenced  by a Document  (including,
without limitation,  a negotiable  document of title). All Instruments,  Chattel
Paper, Securities and certificates of title of the Debtor have been delivered to
the Prime  Administrative  Agent,  to perfect on its behalf and on behalf of the
Administrative Agent.

         Section 3.11  Perfection.  Upon the filing of Uniform  Commercial  Code
financing  statements in the jurisdictions listed on Schedule 4 attached hereto,
and upon the  Administrative  Agent's  obtaining  possession  of all  Documents,
Instruments,  Chattel Paper, Securities and certificates of title of the Debtor,
and  upon  the  Administrative  Agent's  obtaining  control  of  all  Investment
Property,  the security  interest in favor of the  Administrative  Agent created
herein will constitute a valid and perfected Lien upon and security  interest in
the Collateral,  subject to no equal or prior Lien, except in favor of the Prime
Administrative Agent and as permitted by Section 9.2 of the Loan Agreement.

         Section 3.12 Independent  Investigation.  The Debtor has, independently
and  without  reliance  upon any of the Agents or any Lender and based upon such
documents  and  information  as it has deemed  appropriate,  made its own credit
analysis  and  decision to enter into this  Agreement.  There are no  conditions
precedent to the full  effectiveness  of this Agreement that have not been fully
and permanently satisfied.

         Section  3.13  Litigation.  Except as  disclosed on Schedule 7.5 to the
Prime  Agreement,  there  is  no  litigation,   investigation,  or  governmental
proceeding  threatened  against  the  Debtor or any of its  properties  which if
adversely  determined  would have a material adverse effect on the Collateral or
the financial condition,  operations,  or business of the Borrower, any Material
Subsidiary or the Companies taken as a whole.

         Section 3.14 Benefit to Debtor. The value of the consideration received
and to be received by the Debtor as a result of the Borrower, the Agents and the
Lenders entering into the Loan Agreement and the Debtor executing and delivering
this  Agreement  is  reasonably  worth  at least  as much as the  liability  and
obligation of the Debtor  hereunder,  and such  liability and obligation and the
Borrower's entering into the Loan Agreement have benefited and may reasonably be
expected to benefit the Debtor directly and indirectly.

                                   ARTICLE IV

                                    Covenants

         The Debtor  covenants  and agrees  with the  Administrative  Agent that
until the Secured Indebtedness is paid and performed in full and the Commitments
have terminated:

         Section 4.1  Encumbrances.  Except as  permitted  by Section 9.2 of the
Loan Agreement and liens in favor of the Prime Administrative  Agent, the Debtor
shall not create,  permit,  or suffer to exist,  and shall defend the Collateral
against,  any Lien,  security interest,  or other encumbrance on the Collateral,
and shall defend the Debtor's  rights in the Collateral  and the  Administrative
Agent's  security  interest in the Collateral  against the claims and demands of
all  Persons.  The  Debtor  shall  do  nothing  to  impair  the  rights  of  the
Administrative Agent in the Collateral.


<PAGE>


         Section 4.2 Delivery.  Prior to or concurrently  with the execution and
delivery of this  Agreement,  Debtor shall  deliver to the Prime  Administrative
Agent to acknowledge the  Administrative  Agent's lien and security  interest in
all  certificates  identified  on  Schedule 2 hereto,  with all  Chattel  Paper,
Instruments and Documents of the Debtor.

         Section 4.3  Modification of Accounts.  The Debtor shall, in accordance
with prudent  business  practices,  endeavor to collect or cause to be collected
from each  account  debtor  under  its  Accounts,  as and when due,  any and all
amounts  owing under such  Accounts.  Without the prior  written  consent of the
Administrative  Agent,  the Debtor shall not (a) grant any  extension of time on
any  Account  for any payment or grant  extensions  of time for  payments on its
Accounts which cause the aggregate amount of all payments extended by the Debtor
on its Accounts during any fiscal year of the Debtor to exceed $150,000.00,  (b)
compromise,  compound,  or  settle  any of the  Accounts  for less than the full
amount thereof; provided,  however, that the Debtor may compromise,  compound or
settle  any  Account  which is an amount  less  than  $50,000.00,  provided  the
aggregate  amount  compromised,  compounded or settled during any fiscal year of
the Debtor shall not exceed  $150,000.00,  (c) release, in whole or in part, any
Person liable for payment of an Account in excess of  $50,000.00,  (d) allow any
credit  or  discount  for  payment  with  respect  to any  Account  in excess of
$50,000.00,  other  than  trade  discounts  granted  in the  ordinary  course of
business;  provided,  however,  that the  aggregate  amount  of all  credits  or
discounts  granted  during  any  fiscal  year of the  Debtor  shall  not  exceed
$150,000.00,  or (e) release any Lien,  security interest,  or guaranty securing
any Account in excess of $50,000.00.

         Section  4.4  Disposition  of  Collateral.  The Debtor  shall not sell,
lease,  assign (by operation of law or otherwise),  or otherwise  dispose of, or
grant any option with respect to, the Collateral or any part thereof without the
prior written consent of the  Administrative  Agent,  except the Debtor may sell
Inventory in the ordinary course of business.

         Section  4.5  Distributions.  If the Debtor  shall  become  entitled to
receive or shall receive any stock certificate  (including,  without limitation,
any certificate representing a stock dividend or distribution in connection with
any reclassification,  increase, or reduction of capital or issued in connection
with any  reorganization),  option or  rights,  whether  as an  addition  to, in
substitution  of, or an exchange for any  Collateral  or  otherwise,  the Debtor
agrees to accept the same as the  Administrative  Agent's  agent and to hold the
same in trust for the Administrative  Agent and to deliver the same forthwith to
the Prime Administrative Agent in the exact form received,  with the appropriate
endorsement of the Debtor when necessary and/or appropriate undated stock powers
duly executed in blank, to be held by the Prime  Administrative Agent on its own
behalf and on behalf of  Administrative  Agent as additional  Collateral for the
Secured  Indebtedness,  subject  to the terms  hereof.  Any sums paid upon or in
respect of the  Securities  upon the  liquidation  or  dissolution of the issuer
thereof shall be paid over to the Prime Administrative Agent to be held by it as
additional  Collateral for the Secured Indebtedness subject to the terms hereof;
and in case any  distribution  of capital  shall be made on or in respect of the
Securities  or any  property  shall be  distributed  upon or with respect to the
Securities  pursuant to any  recapitalization or reclassification of the capital
of the issuer thereof or pursuant to any  reorganization  of the issuer thereof,
the property so distributed shall be delivered to the Prime Administrative Agent
to be held by it, as additional Collateral for the Secured Indebtedness, subject
to the terms hereof.  All sums of money and property so paid or  distributed  in
respect of the Securities  that are received by the Debtor shall,  until paid or
delivered to the  Administrative  Agent (or the Prime  Administrative  Agent, so
long as it has a prior  lien),  be held by the  Debtor  in trust  as  additional
security for the Secured Indebtedness.


<PAGE>


         Section 4.6 Further Assurances. At any time and from time to time, upon
the request of the Administrative  Agent, and at the sole expense of the Debtor,
the Debtor  shall  promptly  execute and deliver all such  further  instruments,
agreements,  and  documents and take such further  action as the  Administrative
Agent may  reasonably  deem  necessary  or desirable to preserve and perfect its
security interest in the Collateral and carry out the provisions and purposes of
this  Agreement.  Without  limiting the generality of the foregoing,  the Debtor
shall:  (a)  execute  and  deliver to the  Administrative  Agent such  financing
statements  as the  Administrative  Agent  may from  time to time  require;  (b)
deliver  and  pledge to the  Administrative  Agent (or the Prime  Administrative
Agent,  so  long as it has a  prior  lien)  all  Documents  (including,  without
limitation,  negotiable  documents of title) evidencing  Inventory or Equipment;
(c) deliver and pledge to the Administrative  Agent (or the Prime Administrative
Agent, so long as it has a prior lien) all certificates of title required by the
Loan  Agreement,  Instruments and Chattel Paper of the Debtor with any necessary
endorsements; and (d) execute and deliver to the Administrative Agent such other
documents,   instruments,   and  agreements  as  the  Administrative  Agent  may
reasonably  require to perfect and maintain  the  validity,  effectiveness,  and
priority of the Loan Documents and the Liens intended to be created thereby. The
Debtor  authorizes  the  Administrative  Agent to file one or more  financing or
continuation statements,  and amendments thereto, relating to all or any part of
the  Collateral  without the  signature of the Debtor where  permitted by law. A
carbon,  photographic,  or  other  reproduction  of  this  Agreement  or of  any
financing  statement  covering  the  Collateral  or any  part  thereof  shall be
sufficient as a financing statement and may be filed as a financing statement.

         Section 4.7 Risk of Loss;  Insurance.  The Agents and the Lenders shall
not be responsible for any loss or damage to the  Collateral.  The Debtor shall,
at its own expense,  maintain  insurance  with  financially  sound and reputable
insurance  companies  in such  amounts  and  covering  such  risks as is usually
carried  by  corporations  engaged  in similar  businesses  and  owning  similar
properties  in the same general  areas in which the Debtor  operates  consistent
with past  practices  and to the extent  available  on  commercially  reasonable
terms,   provided  that  in  any  event  the  Debtor  will  maintain   workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance,  professional liability insurance and business interruption insurance
reasonably  satisfactory  to the  Administrative  Agent.  Each insurance  policy
covering  Collateral shall name the  Administrative  Agent as loss payee for the
benefit of the Lenders as its  interest  may appear and shall  provide that such
policy will not be canceled or reduced  without  thirty (30) days prior  written
notice to the Administrative Agent.

         Section  4.8   Inspection   Rights.   The  Debtor   shall   permit  the
Administrative  Agent and each Lender and their  respective  representatives  to
examine, inspect, and audit the Collateral and to examine, inspect, and copy the
Debtor's  books  and  records  at  any  reasonable  time  and  as  often  as the
Administrative Agent or any such Lender may desire. The Administrative Agent and
each Lender may at any time and from time to time  contact  account  debtors and
other  obligors  to verify the  existence,  amounts,  and terms of the  Debtor's
Accounts.

         Section 4.9  Corporate  Changes.  The Debtor shall not change its name,
identity,  or corporate  structure  in any manner that might make any  financing
statement filed in connection with this Agreement  seriously  misleading  unless
the Debtor  shall have given the  Administrative  Agent  thirty  (30) days prior
written  notice  thereof  and shall  have  taken all  action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent to make  each  financing
statement  not seriously  misleading.  The Debtor shall not change its principal
place of business, chief executive office, or the place where it keeps its books
and records unless it shall have given the Administrative Agent thirty (30) days
prior written notice thereof and shall have taken all action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent  to cause  its  security
interest in the  Collateral to be perfected  with the priority  required by this
Agreement.

         Section  4.10 Books and  Records;  Information.  The Debtor  shall keep
accurate  and  complete  books and records of the  Collateral  and the  Debtor's
business and financial  condition in accordance with GAAP. The Debtor shall from
time  to  time  at  the  request  of the  Administrative  Agent  deliver  to the
Administrative Agent such information regarding the Collateral and the Debtor as
the Administrative Agent may reasonably request, including,  without limitation,
lists and  descriptions  of the  Collateral  and  evidence of the  identity  and
existence  of the  Collateral.  The Debtor shall mark its records to reflect the
security interest of the Administrative Agent hereunder.


<PAGE>


         Section 4.11      Equipment and Inventory.
                           -----------------------

                  (a) The Debtor shall keep the  Equipment  and Inventory at the
         locations  specified  on  Schedule 3 hereto or,  upon  thirty (30) days
         prior written notice to the Administrative  Agent, at such other places
         within  the  United  States of America  where all  action  required  to
         perfect the  Administrative  Agent's security interest in the Equipment
         and Inventory with the priority  required by this Agreement  shall have
         been taken.

     (b) The Debtor shall  maintain the  Equipment  and  Inventory in accordance
with Section 8.3 of the Loan Agreement.

         Section 4.12 Warehouse Receipts Non-Negotiable.  The Debtor agrees that
if any  warehouse  receipt or receipt  in the nature of a  warehouse  receipt is
issued in respect of any of the Collateral, such warehouse receipt or receipt in
the nature  thereof shall not be  "negotiable"  (as such term is used in Section
7.104 of the Uniform  Commercial Code as in effect in any relevant  jurisdiction
or under relevant law).

         Section  4.13 Taxes and  Claims.  The Debtor  shall pay and  discharge,
before the same become  delinquent,  (a) all material  taxes,  assessments,  and
governmental  charges  imposed upon it or upon any of its property,  and (b) all
material  lawful  claims  that,  if unpaid,  might become a Lien upon any of its
property;  provided,  however,  that the Debtor  shall not be required to pay or
discharge  any such  tax,  assessment,  or  governmental  charge  which is being
contested in good faith by proper  proceedings being diligently  pursued and for
which adequate reserves have been established in accordance with GAAP.

         Section  4.14  Compliance  with Laws.  The Debtor  shall  comply in all
material respects with all material applicable laws, rules, regulations, orders,
and decrees of any Governmental Authority or arbitrator.

         Section 4.15 Compliance with Agreements. The Debtor shall comply in all
material respects with all agreements,  contracts, and instruments binding on it
or affecting  its  properties or  businesses,  except where the failure to do so
would not have a material adverse effect on the business,  condition  (financial
or otherwise), operations or properties of the Borrower, any Material Subsidiary
or the Companies (taken as a whole).

         Section  4.16  Notification.  Except as permitted by Section 9.2 of the
Loan  Agreement  and Section 9.2 of the Prime Loan  Agreement,  the Debtor shall
promptly notify the  Administrative  Agent of (a) any Lien,  security  interest,
encumbrance,  or claim that has attached to or been made or asserted against any
of the Collateral, (b) any material change in any of the Collateral,  including,
without  limitation,  any material damage to or loss of any material  portion of
the Collateral, (c) the occurrence of any other event that could have a material
adverse effect on the Collateral or the security interest created hereunder, and
(d) the occurrence or existence of any Default.

         Section 4.17  Collection of Accounts.  Except as otherwise  provided in
this Section or in any other Loan  Document,  the Debtor shall have the right to
collect  and  receive  payments  on  the  Accounts.   In  connection  with  such
collections,  the Debtor may take (and, at the Administrative Agent's direction,
shall  take)  such  actions  as the  Debtor  or  the  Administrative  Agent  may
reasonably deem necessary or advisable to enforce collection of the Accounts.

         Section 4.18 Additional Securities.  The Debtor shall not consent to or
approve the issuance of any  additional  shares of any class of capital stock of
the issuers of any of the  Securities,  or any securities  convertible  into, or
exchangeable  for, any such shares or any warrants,  options,  rights,  or other
commitments  entitling  any Person to  purchase  or  otherwise  acquire any such
shares.


<PAGE>


         Section 4.19 Provide Information.  The Debtor shall fully cooperate, to
the extent reasonably  requested by the Administrative  Agent, in the completion
of any notice,  form,  schedule,  or other document filed by the  Administrative
Agent  on its  own  behalf  or on  behalf  of  the  Debtor,  including,  without
limitation,  any required notice or statement of beneficial  ownership or of the
acquisition of beneficial ownership of the Securities and any notice of proposed
sale of such  Securities  pursuant to Rule 144 as  promulgated by the Securities
and  Exchange  Commission  (the  "SEC")  under the  Securities  Act of 1933,  as
amended.  Without  limiting the  generality of the  foregoing,  the Debtor shall
furnish  to  the  Administrative   Agent  any  and  all  information  which  the
Administrative  Agent may  reasonably  request for  purposes of any such filing,
regarding the Debtor,  the Securities,  and any issuer of any of the Securities,
and the Debtor shall disclose to the  Administrative  Agent all material adverse
information  known by the Debtor with respect to the operations of any issuer of
any of the Securities.

         Section  4.20  Notification  of Changes in  Beneficial  Ownership.  The
Debtor shall promptly notify the Administrative  Agent of any sale of securities
of any  Subsidiary of the Debtor or by any Person named on the Debtor's Rule 144
questionnaire and shall furnish promptly to the  Administrative  Agent a copy of
any Form 144 filed in respect of any such sale.  In  addition,  if the Debtor or
any other Person named in the Debtor's  Rule 144  questionnaire  shall file with
the  SEC a form  or  other  document  reporting  any  change  in the  beneficial
ownership of the common stock of any Subsidiary of the Debtor,  the Debtor shall
promptly furnish to the Administrative Agent a copy of such form or document.

         Section 4.21  Restriction on Sales after Default.  The Debtor shall not
sell or  suffer  or  permit  any  Person  named  in the  accompanying  Rule  144
questionnaire  to sell  any  shares  of the  same  class  of  securities  as the
Securities at any time after any Event of Default shall have occurred.

         Section  4.22  Fixtures.  For any  Collateral  that is a fixture  or an
accession  which has been  attached  to real  estate or other goods prior to the
perfection of the security  interest  granted in Section 2.1 hereof,  the Debtor
shall furnish to Administrative  Agent, upon demand, a disclaimer of interest in
each such fixture or accession and a consent in writing to the security interest
of Administrative  Agent therein,  signed by all persons and entities having any
interest  in such  fixture or  accession  by virtue of any  interest in the real
estate or other goods to which such fixture or accession has been attached.

         Section 4.23 Notation on Title  Certificates.  If certificates of title
are issued or  outstanding  with  respect to any of the  Collateral,  the Debtor
shall cause the security  interest  granted in Section 2.1 hereof to be properly
noted thereon.

                                    ARTICLE V

                       Rights of the Administrative Agent

         Section  5.1  Power  of  Attorney.   The  Debtor   hereby   irrevocably
constitutes  and  appoints  the  Administrative  Agent and any  officer or agent
thereof,   with   full   power  of   substitution,   as  its  true  and   lawful
attorney-in-fact  with full  irrevocable  power and authority in the name of the
Debtor or in its own name, to take any and all action and to execute any and all
documents and instruments  which the  Administrative  Agent at any time and from
time to time deems reasonably  necessary or desirable to accomplish the purposes
of this  Agreement if an Event of Default shall have occurred and be continuing,
and, without  limiting the generality of the foregoing,  the Debtor hereby gives
the Administrative  Agent the power and right on behalf of the Debtor and in its
own name to do any of the  following  (subject to the rights of the Debtor under
Sections 5.2 and 5.3 hereof),  without notice to or the consent of the Debtor if
an Event of Default shall have occurred and be continuing:


<PAGE>


                  (a) to demand, sue for, collect, or receive in the name of the
         Debtor or in its own name, any money or property at any time payable or
         receivable on account of or in exchange for any of the Collateral  and,
         in connection therewith,  endorse checks,  notes, drafts,  acceptances,
         money  orders,  documents of title,  or any other  instruments  for the
         payment of money under the Collateral or any policy of insurance;

               (b) to pay or  discharge  taxes,  Liens,  or  other  encumbrances
          levied or placed on or threatened against the Collateral;

               (c) to notify post office  authorities  to change the address for
          delivery  of  mail  of the  Debtor  to an  address  designated  by the
          Administrative Agent and to receive, open. and subsequently deliver to
          the Debtor mail addressed to the Debtor; and

                  (d) (i) to direct account debtors and any other parties liable
         for any payment under any of the  Collateral to make payment of any and
         all  monies  due  and  to  become  due   thereunder   directly  to  the
         Administrative  Agent or as the Administrative Agent shall direct; (ii)
         to receive payment of and receipt for any and all monies,  claims,  and
         other  amounts  due and to  become  due at any  time in  respect  of or
         arising out of any Collateral;  (iii) to sign and endorse any invoices,
         freight  or  express  bills,  bills of  lading,  storage  or  warehouse
         receipts, drafts against debtors,  assignments,  proxies, stock powers,
         verifications,  and  notices  in  connection  with  accounts  and other
         documents  relating to the  Collateral;  (vi) to commence and prosecute
         any suit,  action,  or  proceeding  at law or in equity in any court of
         competent  jurisdiction  to collect the  Collateral or any part thereof
         and to enforce  any other  right in respect of any  Collateral;  (v) to
         defend any suit,  action, or proceeding brought against the Debtor with
         respect to any Collateral;  (vi) to settle,  compromise,  or adjust any
         suit,  action,  or  proceeding   described  above  and,  in  connection
         therewith,  to give such  discharges or releases as the  Administrative
         Agent may deem appropriate; (vii) to exchange any of the Collateral for
         other   property  upon  any  merger,   consolidation,   reorganization,
         recapitalization,  or other  readjustment of the issuer thereof and, in
         connection therewith, deposit any of the Collateral with any committee,
         depositary,  transfer agent, registrar, or other designated agency upon
         such terms as the Administrative Agent may determine;  (viii) to add or
         release any guarantor,  indorser,  surety, or other party to any of the
         Collateral;  (ix) to renew,  extend,  or otherwise change the terms and
         conditions of any of the Collateral;  (x) to make, settle,  compromise,
         or  adjust  claims  under  any  insurance  policy  covering  any of the
         Collateral;  (xi) to sell,  transfer,  pledge,  make any agreement with
         respect to or otherwise  deal with any of the  Collateral  as fully and
         completely as though the  Administrative  Agent were the absolute owner
         thereof  for all  purposes,  and to do, at the  Administrative  Agent's
         option and the Debtor's expense, at any time, or from time to time, all
         acts and things  which the  Administrative  Agent  deems  necessary  to
         protect,   preserve,   or   realize   upon  the   Collateral   and  the
         Administrative   Agent's  security  interest  therein;   and  (xii)  to
         complete, execute and file with the SEC one or more notices of proposed
         sale of securities pursuant to Rule 144.

         This power of attorney is a power coupled with an interest and shall be
irrevocable.  Neither the Administrative Agent nor any Lender shall be under any
duty  to  exercise  or  withhold  the  exercise  of any of the  rights,  powers,
privileges,  and options expressly or implicitly  granted to the  Administrative
Agent in this Agreement, and shall not be liable for any failure to do so or any
delay in doing so.  Neither  the  Administrative  Agent nor any Lender  shall be
liable for any act or  omission  or for any error of  judgment or any mistake of
fact or law in its  individual  capacity or in its capacity as  attorney-in-fact
except  acts or  omissions  resulting  from  its  gross  negligence  or  willful
misconduct.  This power of attorney is  conferred  on the  Administrative  Agent
solely to protect,  preserve,  and  realize  upon its  security  interest in the
Collateral. Neither the Administrative Agent nor any Lender shall be responsible
for any decline in the value of the Collateral and shall not be required to take
any steps to preserve rights against prior parties or to protect,  preserve,  or
maintain any security interest or Lien given to secure the Collateral.


<PAGE>


         Section 5.2 Voting  Rights.  Unless and until an Event of Default shall
have  occurred and be  continuing,  the Debtor shall be entitled to exercise any
and all voting rights  pertaining to the  Securities or any part thereof for any
purpose not inconsistent with the terms of this Agreement or the Loan Agreement.
The  Administrative  Agent  shall  execute  and  deliver  to the Debtor all such
proxies  and other  instruments  as the Debtor may  reasonably  request  for the
purpose  of  enabling  the Debtor to  exercise  the  voting  rights  which it is
entitled to exercise pursuant to this Section.

         Section 5.3 Dividends.  Unless and until an Event of Default shall have
occurred and be  continuing,  the Debtor shall be entitled to receive and retain
the dividends on the Securities paid in cash out of earned surplus to the extent
and only to the extent that such dividends are permitted by the Loan Agreement.

         Section 5.4 Setoff,  Property Held by the Lenders.  The  Administrative
Agent and each  Lender  shall  have the right to set off and apply  against  the
Secured Indebtedness,  at any time and without notice to the Debtor, any and all
deposits  (general or special,  time or demand,  provisional  or final) or other
sums at any time  credited  by or owing  from  the  Administrative  Agent or any
Lender to the Debtor  whether or not the  Secured  Indebtedness  is then due. As
additional security for the Secured  Indebtedness,  the Debtor hereby grants the
Administrative  Agent  and  each  Lender  a  security  interest  in  all  money,
instruments,  and other  property  of the  Debtor now or  hereafter  held by the
Administrative Agent or any Lender, including without limitation,  property held
in  safekeeping.  In addition to the  Administrative  Agent's and each  Lender's
right of setoff and as further security for the Secured Indebtedness, the Debtor
hereby  grants to each of them a security  interest in all deposits  (general or
special, time or demand, provisional or final) of the Debtor now or hereafter on
deposit  with or held by any of them and all other sums at any time  credited by
or owing from the any of them to the  Debtor.  The rights  and  remedies  of the
Administrative  Agent and each Lender  hereunder are in addition to other rights
and remedies (including,  without limitation,  other rights of setoff) which any
of them may have.

         Section 5.5  Performance by the Secured Party. If the Debtor shall fail
to  perform  any  covenant  or  agreement  contained  in  this  Agreement,   the
Administrative Agent, may, at the direction of the Required Lenders,  perform or
attempt to perform such  covenant or agreement on behalf of the Debtor.  In such
event, the Debtor shall, at the request of the  Administrative  Agent,  promptly
pay any amount expended by the Administrative  Agent or any Lender in connection
with such  performance  or attempted  performance to the  Administrative  Agent,
together with  interest  thereon at the Default Rate from and including the date
of such  expenditure to but excluding the date such expenditure is paid in full.
Notwithstanding  the  foregoing,   it  is  expressly  agreed  that  neither  the
Administrative  Agent nor any Lender shall have any liability or  responsibility
for the performance of any obligations of the Debtor under this Agreement.

                                   ARTICLE VI

                                     Default

         Section  6.1 Rights  and  Remedies.  If an Event of Default  shall have
occurred and be continuing,  the  Administrative  Agent shall have the following
rights and remedies:


<PAGE>


                  (a) In addition to all other  rights and  remedies  granted to
         the  Administrative  Agent  in  this  Agreement  or in any  other  Loan
         Document or by applicable law, the Administrative  Agent shall have all
         of the rights and remedies of a secured party under the UCC (whether or
         not the UCC applies to the affected  Collateral).  Without limiting the
         generality of the foregoing,  the Administrative  Agent may (i) without
         demand or notice to the Debtor, collect, receive, or take possession of
         the   Collateral   or  any  part  thereof  and  for  that  purpose  the
         Administrative   Agent  may  enter  upon  any  premises  on  which  the
         Collateral is located and remove the Collateral  therefrom or render it
         inoperable,  and/or  (ii)  sell,  lease,  or  otherwise  dispose of the
         Collateral,  or any part  thereof,  in one or more parcels at public or
         private  sale  or  sales,  at the  Administrative  Agent's  offices  or
         elsewhere,  for cash, on credit or for future  delivery,  and upon such
         other  terms  as  the   Administrative   Agent  may  deem  commercially
         reasonable. The Administrative Agent shall have the right at any public
         sale or sales,  and, to the extent  permitted by applicable law, at any
         private sale or sales,  to bid and become a purchaser of the Collateral
         or any part  thereof free of any right or equity of  redemption  on the
         part of the  Debtor,  which  right or  equity of  redemption  is hereby
         expressly  waived and  released by the Debtor.  Upon the request of the
         Administrative Agent, the Debtor shall assemble the Collateral and make
         it available to the Administrative Agent at any place designated by the
         Administrative  Agent that is  reasonably  convenient to the Debtor and
         the  Administrative  Agent.  The Debtor agrees that the  Administrative
         Agent shall not be  obligated  to give more than five (5) days  written
         notice of the time and place of any  public  sale or of the time  after
         which  any  private  sale may take  place and that  such  notice  shall
         constitute  reasonable notice of such matters. The Administrative Agent
         shall  not be  obligated  to make  any sale of  Collateral  if it shall
         determine  not to do so,  regardless of the fact that notice of sale of
         Collateral may have been given. The  Administrative  Agent may, without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place fixed for sale, and such sale may,  without  further  notice,  be
         made at the time and  place to  which  the same was so  adjourned.  The
         Debtor shall be liable for all expenses of retaking, holding, preparing
         for sale, or the like, and all attorneys' fees, legal expenses, and all
         other costs and expenses  incurred by the  Administrative  Agent or any
         Lender in connection  with the  collection of the Secured  Indebtedness
         and the  enforcement  of the  Administrative  Agent's and the  Lender's
         rights under this  Agreement.  The Debtor  shall remain  liable for any
         deficiency  if the  Proceeds  of any sale or other  disposition  of the
         Collateral are  insufficient  to pay the Secured  Indebtedness in full.
         The  Administrative  Agent and the  Lenders  may  apply the  Collateral
         against  the  Secured  Indebtedness  in such  order  and  manner as the
         Administrative  Agent and the Lenders may elect.  The Debtor waives all
         rights of  marshaling,  valuation,  and  appraisal  in  respect  of the
         Collateral.

                  (b)  The  Administrative  Agent  may  cause  any or all of the
         Collateral  held  by  it  to  be  transferred  into  the  name  of  the
         Administrative Agent or the name or names of the Administrative Agent's
         nominee or nominees.

                  (c) The  Administrative  Agent  may  exercise  or  cause to be
         exercised  all voting,  consensual  and other  powers of  ownership  in
         respect  of  the  Collateral  and  the  Debtor  shall  deliver  to  the
         Administrative   Agent,  if  requested  by  the  Administrative  Agent,
         irrevocable proxies with respect to the Securities in form satisfactory
         to the Administrative Agent.

                  (d) The Administrative  Agent may collect or receive all money
         or  property  at any time  payable  or  receivable  on account of or in
         exchange for any of the Collateral, but shall be under no obligation to
         do so.

                  (e) On any sale of the Collateral, the Administrative Agent is
         hereby  authorized to comply with any  limitation or  restriction  with
         which  compliance  is  necessary,  in the  view  of the  Administrative
         Agent's  counsel,  in order to avoid any violation of applicable law or
         in order to obtain any required approval of the purchaser or purchasers
         by any applicable Governmental Authority.


<PAGE>


                  (f) The Debtor agrees that,  because of the  Securities Act of
         1933,  as  amended,  or any other  laws or  regulations,  and for other
         reasons,   there  may  be  legal  and/or   practical   restrictions  or
         limitations  affecting  the  Administrative  Agent in any  attempts  to
         dispose of certain  portions of the Securities and for the  enforcement
         of their rights. For these reasons,  the Administrative Agent is hereby
         authorized by the Debtor,  but not  obligated,  upon the occurrence and
         during the continuation of an Event of Default, to sell all or any part
         of the Securities at private sale,  subject to investment  letter or in
         any other  manner  which will not require the  Securities,  or any part
         thereof,  to be  registered in accordance  with the  Securities  Act of
         1933, as amended, or the rules and regulations  promulgated thereunder,
         or any other laws or regulations, at a reasonable price at such private
         sale or other  distribution in the manner  mentioned  above. The Debtor
         understands  that  the  Administrative  Agent  may  in  its  discretion
         approach a limited number of potential purchasers and that a sale under
         such  circumstances may yield a lower price for the Securities,  or any
         part or party  thereof,  than would  otherwise  be  obtainable  if such
         collateral  were  either  afforded  to a  larger  number  or  potential
         purchasers, or registered or sold in the open market. The Debtor agrees
         that  such  private  sale  shall  be  deemed  to  have  been  made in a
         commercially  reasonable manner, and that the Administrative  Agent has
         no  obligation  to delay  sale of any  Securities  to permit the issuer
         thereof to register it for public sale under any applicable  federal or
         state  securities  laws. The  Administrative  Agent is  authorized,  in
         connection with any such sale (a) to restrict the  prospective  bidders
         on or  purchasers  of any of the  Securities  to a  limited  number  of
         sophisticated  investors  who will  represent  and agree  that they are
         purchasing  for their own account for investment and not with a view to
         the  distribution  or sale of any of such  Securities and (b) to impose
         such other  limitations or conditions in connection  with any such sale
         as the  Administrative  Agent  reasonably  deems  necessary in order to
         comply with  applicable  law. The Debtor  covenants  and agrees that it
         will execute and deliver such  documents  and take such other action as
         the  Administrative  Agent reasonably deems necessary in order that any
         such sale may be made in compliance  with applicable law. Upon any such
         sale the Administrative  Agent shall have the right to deliver,  assign
         and transfer to the  purchaser  thereof the  Securities  so sold.  Each
         purchaser  at  any  such  sale  shall  hold  the   Securities  so  sold
         absolutely,  free from any claim or right of the  Debtor of  whatsoever
         kind,  including any equity or right of  redemption of the Debtor.  The
         Debtor, to the extent permitted by applicable law, hereby  specifically
         waives all rights of redemption,  stay or appraisal which it has or may
         have under any law now existing or hereafter enacted.

                                   ARTICLE VII

                                  Miscellaneous

         Section 7.1 Indemnification. The Debtor hereby agrees to indemnify each
Agent,  each Lender and each Affiliate  thereof and their  respective  officers,
directors,  employees,  attorneys,  and agents  (collectively  the  "Indemnified
Parties")  from,  and hold each of them  harmless  against,  any and all losses,
liabilities,  claims, damages, penalties, judgments,  disbursements,  costs, and
expenses (including  reasonable attorneys' fees) to which any of them may become
subject  which  directly  or  indirectly   arise  from  or  relate  to  (a)  the
negotiation, execution, delivery, performance, administration, or enforcement of
this  Agreement  or any  other  Loan  Document,  (b)  any  of  the  transactions
contemplated by this Agreement or any other Loan Document, (c) any breach by the
Debtor of any representation,  warranty,  covenant, or other agreement contained
in  this  Agreement  or any  other  Loan  Document,  or (d)  any  investigation,
litigation, or other proceeding,  including,  without limitation, any threatened
investigation, litigation, or other proceeding relating to any of the foregoing,
INCLUDING,  WITHOUT  LIMITATION,  THOSE  ARISING  FROM THE SOLE OR  CONTRIBUTORY
NEGLIGENCE OF ANY INDEMNIFIED PARTY.

         Section 7.2 No Waiver;  Cumulative Remedies.  No failure on the part of
any Agent or the Lender to exercise and no delay in exercising, and no course of
dealing with respect to, any right,  power,  or privilege  under this  Agreement
shall operate as a waiver thereof,  nor shall any single or partial  exercise of
any right,  power,  or  privilege  under this  Agreement  preclude  any other or
further  exercise  thereof  or  the  exercise  of any  other  right,  power,  or
privilege. The rights and remedies provided for in this Agreement are cumulative
and not exclusive of any rights and remedies provided by law.

         Section 7.3  Successors and Assigns.  This  Agreement  shall be binding
upon and inure to the benefit of the Debtor,  the Agents,  the Lenders and their
respective heirs, successors, and assigns, except that the Debtor may not assign
any of its rights or obligations  under this Agreement without the prior written
consent of the Administrative Agent.


<PAGE>


         Section 7.4 Amendment;  Entire Agreement.  THIS AGREEMENT  EMBODIES THE
FINAL,  ENTIRE  AGREEMENT  AMONG THE PARTIES  HERETO AND  SUPERSEDES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN  OR  ORAL,  RELATING  TO  THE  SUBJECT  MATTER  HEREOF  AND  MAY  NOT BE
CONTRADICTED OR VARIED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS OR SUBSEQUENT ORAL
AGREEMENTS OR DISCUSSIONS OF THE PARTIES  HERETO.  THERE ARE NO ORAL  AGREEMENTS
AMONG THE PARTIES  HERETO.  The  provisions of this  Agreement may be amended or
waived only by an instrument in writing signed by the parties hereto.

         Section 7.5 Notices. All notices and other communications  provided for
in this Agreement shall be given or made in accordance with Section 13.11 of the
Loan Agreement to the intended  recipient at the "Address for Notices" specified
below its name on the signature pages hereof,  or, as to any party at such other
address  as shall be  designated  by such  party in a notice to the other  party
given in accordance with this Section.

         Section 7.6  Governing  Law.  THIS  AGREEMENT  SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.

     Section 7.7 Headings. The headings, captions, and arrangements used in this
Agreement are for convenience  only and shall not affect the  interpretation  of
this Agreement.

         Section  7.8   Survival  of   Representations   and   Warranties.   All
representations  and  warranties  made in this  Agreement or in any  certificate
delivered  pursuant  hereto  shall  survive the  execution  and delivery of this
Agreement,  and no  investigation  by any Agent or any Lender  shall  affect the
representations  and  warranties or the right of any Agent or any Lender to rely
upon them.

         Section 7.9 Waiver of Bond. In the event the Administrative Agent seeks
to take  possession  of any or all of the  Collateral by judicial  process,  the
Debtor hereby  irrevocably  waives any bonds and any surety or security relating
thereto  that  may  be  required  by  applicable  law  as an  incident  to  such
possession,  and waives any demand for possession  prior to the  commencement of
any such suit or action.

         Section 7.10  Severability.  Any provision of this  Agreement  which is
prohibited or unenforceable in any jurisdiction  shall, as to such jurisdiction,
be ineffective to the extent of such  prohibition  or  unenforceability  without
invalidating  the  remaining   provisions  of  this  Agreement,   and  any  such
prohibition  or  unenforceability  in any  jurisdiction  shall not invalidate or
render unenforceable such provision in any other jurisdiction.

         Section  7.11  Construction.  The Debtor and the  Administrative  Agent
acknowledge  that each of them has had the  benefit of legal  counsel of its own
choice and has been afforded an  opportunity  to review this  Agreement with its
legal counsel.

     Section  7.12  Obligations  Absolute.   All  rights  and  remedies  of  the
Administrative  Agent  hereunder,  and all obligations of the Debtor  hereunder,
shall be absolute and unconditional irrespective of:

               (a) any lack of validity or  enforceability of the Loan Agreement
          or any  of  the  other  Loan  Documents  or  any  other  agreement  or
          instrument relating to any of the foregoing;

                   (b) any change in the time,  manner,  or place of payment of,
         or in any other term of, all or any of the Secured Indebtedness, any or
         all of the  Obligations,  or any  other  amendment  or waiver of or any
         consent to any  departure  from the Loan  Agreement or any of the other
         Loan Documents;


<PAGE>


               (c) any exchange, release, or nonperfection of any Collateral, or
          any release or amendment or waiver of or consent to any departure from
          any guarantee, for all or any of the Secured Indebtedness; or

                   (d) any other circumstance (other than payment in full of the
         Secured   Indebtedness)  that  might  otherwise  constitute  a  defense
         available to, or a discharge of, the Debtor.

         Section 7.13 Limitations. Notwithstanding any contrary provision, it is
the intention of Debtor,  Lenders, and Administrative Agent that the granting of
the  liens  set  forth in this  Agreement  shall  not  constitute  a  fraudulent
conveyance,   fraudulent  transfer,   or  similar  Laws  applicable  to  Debtor.
Accordingly,   notwithstanding  anything  to  the  contrary  contained  in  this
Agreement or any other agreement or instrument executed in connection  herewith,
granting of liens set forth in this  Agreement  shall be limited to an aggregate
amount  equal  to the  largest  amount  that  would  not  render  such  Debtor's
obligations  hereunder  subject to  avoidance  under  Section  548 of the United
Stated Bankruptcy Code or any comparable provision of any applicable state law.

         Section 7.14 Termination. If all of the Secured Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Debtor and in  accordance  with  applicable  provisions  of the Loan  Agreement,
promptly  execute and deliver to the Debtor a proper  instrument or  instruments
acknowledging  the release and termination of the security  interests created by
this  Agreement as the Debtor may reasonably  deem  necessary or desirable,  and
shall duly assign and deliver to the Debtor  (without  recourse  and without any
representation  or warranty)  such of the Collateral as may be in the possession
of the  Administrative  Agent  and has not  previously  been  sold or  otherwise
applied pursuant to this Agreement.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.
                            SIGNATURE PAGE TO FOLLOW.


<PAGE>



                          Guarantor Security Agreement

         IN WITNESS  WHEREOF,  the Debtor has duly executed this Agreement as of
the day and year first written above.

                                                 DEBTOR:
                                                 ------

                                                 PRIME PRACTICE MANAGEMENT, INC.
                                                  a New York corporation

                                                     By: /s/ Teena E. Belcik
                                                         Teena E. Belcik

                                                            Treasurer

                                               Address for Notices:

                                               1301 Capital of Texas Highway
                                               Suite C-300
                                               Austin, Texas 78746
                                               Attn: Treasurer
                                               Fax Number:  (512) 328-8510
                                               Telephone Number:  (512) 314-4554


<PAGE>




                                       20

                          Guarantor Security Agreement

                                                     SCHEDULE 1

                                                   MOTOR VEHICLES

None.


<PAGE>


                                   SCHEDULE 2

                                   SECURITIES

                                  Pledged Stock

None.


<PAGE>


                                   SCHEDULE 3

                             LOCATION OF COLLATERAL

                       Location of Equipment and Inventory

1301 Capital of Texas Highway
Suite C-300

Austin, Travis County, Texas 78746-6550


<PAGE>


                                   SCHEDULE 4

                            JURISDICTIONS FOR FILING

               Jurisdictions for Filing UCC-1 Financing Statements

Texas


<PAGE>


                                                    Guarantor Security Agreement

                          GUARANTOR SECURITY AGREEMENT

         THIS GUARANTOR SECURITY AGREEMENT (the "Agreement") dated as of January
31, 2000,  is executed by FASTSTART,  INC., a North  Carolina  corporation  (the
"Debtor"),  for the  benefit  of BANK  OF  AMERICA,  N.A.,  a  national  banking
association  ("B  of  A"),  not  in  its  individual   capacity  but  solely  as
administrative  agent for itself and each of the other Lenders (each, a "Lender"
and  collectively,   the  "Lenders")  as  defined  in  the  Loan  Agreement  (as
hereinafter defined) (in such capacity, together with its successors and assigns
in such capacity, the "Administrative Agent").

                                R E C I T A L S:
                                 - - - - - - - -

     A. Prime Medical Services, Inc., a Delaware corporation (the "Borrower"), B
of A, as administrative agent, BankBoston, N.A., as documentation agent, and the
Lenders  have  entered  into that  certain  Fourth  Amended  and  Restated  Loan
Agreement  dated  January  31,  2000,  (as the  same may be  amended,  restated,
extended,  supplemented  or modified from time to time,  the "Loan  Agreement"),
pursuant  to which  the  Lenders  have  agreed to make a  revolving  loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Eighty-Six  Million  and  00/100  Dollars   ($86,000,000.00)  at  any  one  time
outstanding.

         B. The  Debtor,  together  with other  guarantors,  has  executed  that
certain  Guaranty  Agreement of even date  herewith (as the same may be amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
the Debtor has  guaranteed to the Agents (as defined in the Loan  Agreement) and
the Lenders the full and complete payment and performance of the Obligations (as
defined in the Loan Agreement).

     C. The Agents and the Lenders have conditioned  their obligations under the
Loan Agreement upon the execution and delivery of this Agreement by the Debtor.

         NOW  THEREFORE,  in  consideration  of the  premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

                                    ARTICLE I

                                   Definitions

         Section 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         Section 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.

     Section  1.3  Additional  Definitions.  As  used  in  this  Agreement,  the
following terms shall have the following meanings:



<PAGE>





                                       16

                                                    Guarantor Security Agreement

                  "Accounts"  means any  "account,"  as such term is  defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor, and, in any
event, shall include,  without  limitation,  each of the following,  whether now
owned or  hereafter  acquired  by the  Debtor:  (a) all  rights of the Debtor to
payment for goods sold or leased or services rendered,  whether or not earned by
performance;  (b) all accounts  receivable of the Debtor;  (c) all rights of the
Debtor to receive any payment of money or other form of  consideration;  (d) all
security pledged, assigned, or granted to or held by the Debtor to secure any of
the foregoing;  (e) all guaranties of, or indemnifications  with respect to, any
of the foregoing;  and (f) all rights of the Debtor as an unpaid seller of goods
or services,  including,  but not limited to, all rights of stoppage in transit,
replevin, reclamation, and resale.

                  "Chattel  Paper"  means any  "chattel  paper," as such term is
defined in Article 9 of the UCC, now owned or hereafter acquired by the Debtor.

                  "Collateral" has the meaning  specified in Section 2.1 of this
Agreement.

                  "Document"  means any  "document,"  as such term is defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor,  including,
without limitation, all documents of title and warehouse receipts of the Debtor.

                  "Equipment"  means any "equipment," as such term is defined in
Article 9 of the UCC, now owned or hereafter  acquired by the Debtor and, in any
event, shall include, without limitation, all machinery, equipment, furnishings,
and  fixtures  now owned or  hereafter  acquired  by the  Debtor and any and all
additions,  substitutions,  and  replacements of any of the foregoing,  wherever
located,  together  with all  attachments,  components,  parts,  equipment,  and
accessories installed thereon or affixed thereto.

                  "General Intangibles" means any "general intangibles," as such
term is defined in Article 9 of the UCC, now owned or hereafter  acquired by the
Debtor  and,  in any  event,  shall  include,  without  limitation,  each of the
following, whether now owned or hereafter acquired by the Debtor: (a) all of the
Debtor's patents, patent applications, patent rights, service marks, trademarks,
trade names,  trade secrets,  intellectual  property,  registrations,  goodwill,
copyrights,  franchises,  licenses, permits,  proprietary information,  customer
lists, designs, and inventions;  (b) all of the Debtor's books,  records,  data,
plans,  manuals,  computer  software,  and  computer  programs;  (c)  all of the
Debtor's  contract  rights,   partnership  interests,   joint  venture,  limited
liability  company,  and  membership  interests  (but  only  to the  extent  not
otherwise pledged to the  Administrative  Agent pursuant to a separate pledge or
security agreement),  deposit accounts, investment accounts, and certificates of
deposit;  (d) all rights of the Debtor to  payment  under  letters of credit and
similar agreements; (e) all tax refunds and tax refund claims of the Debtor; (g)
all  choses in action and  causes of action of the  Debtor  (whether  arising in
contract, tort, or otherwise and whether or not currently in litigation) and all
judgments in favor of the Debtor;  (g) all rights and claims of the Debtor under
warranties  and  indemnities;  and  (h)  all  rights  of the  Debtor  under  any
insurance, surety, or similar contract or arrangement.

                  "Instrument"  means any  "instrument," as such term is defined
in  Article 9 of the UCC and any note  payable  to Debtor or its order  together
with all collateral  securing such note and all agreements and documents related
thereto or arising therefrom, now owned or hereafter acquired by the Debtor.

                  "Inventory"  means any "inventory," as such term is defined in
Article 9 of the UCC, now owned or hereafter acquired by the Debtor, and, in any
event, shall include,  without  limitation,  each of the following,  whether now
owned or  hereafter  acquired  by the Debtor:  (a) all goods and other  personal
property of the Debtor that are held for sale or lease or to be furnished  under
any contract of service; (b) all raw materials, work-in-process, finished goods,
inventory,  supplies, and materials of the Debtor; (c) all wrapping,  packaging,
advertising,  and shipping materials of the Debtor; (d) all goods that have been
returned to,  repossessed  by, or stopped in transit by the Debtor;  and (e) all
Documents evidencing any of the foregoing.

                  "Investment  Property"  means  "investment  property," as such
term is defined in Section 9.115(a)(6) of the Texas Business and Commerce Code.


<PAGE>


                  "Motor Vehicle" means all cars,  trucks,  vans and other motor
vehicles  now owned or  hereafter  acquired by the Debtor  which are used by the
Debtor for the transfer of  lithotripters  and  lithotripsy  related  equipment,
including without limitation,  those motor vehicles listed on Schedule 1 hereto,
and  any and all  attachments,  components,  parts,  equipment  and  accessories
installed thereon or affixed thereto.

                  "Proceeds"  means any  "proceeds,"  as such term is defined in
Article 9 of the UCC and, in any event,  shall  include,  but not be limited to,
(a) any and all  proceeds of any  insurance,  indemnity,  warranty,  or guaranty
payable to the Debtor from time to time with  respect to any of the  Collateral,
(b) any and all payments (in any form whatsoever) made or due and payable to the
Debtor  from  time to time in  connection  with any  requisition,  confiscation,
condemnation, seizure, or forfeiture of all or any part of the Collateral by any
Governmental  Authority  (or any  person  acting  under  color  of  Governmental
Authority),  and (c) any and all other amounts from time to time paid or payable
under or in connection with any of the Collateral.

                  "Securities" means all shares of stock of any Person now owned
or hereafter acquired by the Debtor including,  without limitation,  each of the
shares listed on Schedule 2 hereto,  and all dividends,  cash,  stock dividends,
instruments and other investment property from time to time received, receivable
by, or otherwise  distributed to the Debtor for its own account in respect of or
in exchange for any or all of such  shares,  and the  certificates  representing
such shares.

                  "UCC"  means the Uniform  Commercial  Code as in effect in the
State of Texas or, if so required with respect to any  particular  Collateral by
mandatory  provisions of  applicable  law, as in effect in the  jurisdiction  in
which such Collateral is located.

                                   ARTICLE II

                          Security Interest and Pledge

         Section 2.1 Security Interest and Pledge. The Debtor hereby pledges and
grants to the  Administrative  Agent, for the pro rata benefit of the Lenders, a
lien on and security interest in all of the Debtor's right,  title, and interest
in and to the following,  whether now owned or hereafter arising or acquired and
wherever located (collectively, the "Collateral"):

                  (a)      all Accounts;

                  (b)      all Chattel Paper;

                  (c)      all Instruments;

                  (d)      all General Intangibles and all Securities;

                  (e)      all Investment Property;

                  (f)      all Documents;

               (g) all  Equipment,  including,  without  limitation,  all  Motor
          Vehicles;

                 (h) all Inventory;

               (i) all other goods and personal  property of the Debtor  whether
          tangible or intangible; and


<PAGE>


              (j)      all Proceeds and products of any or all of the foregoing.

         Section 2.2  Secured  Indebtedness.  The  Collateral  shall  secure the
following  obligations,   indebtedness,   and  liabilities  (whether  at  stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

               (a)  the  Obligations  and  the   obligations,   liabilities  and
          indebtedness  of the Debtor to the Agents  and the  Lenders  under the
          Guaranty;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the Collateral, collect the
obligations herein described, and enforce this Agreement; and

               (c) all extensions,  renewals,  and  modifications  of any of the
          foregoing.

         Section  2.3 Debtor  Remains  Liable.  Notwithstanding  anything to the
contrary  contained  herein,  (a) the  Debtor  shall  remain  liable  under  the
contracts  and  agreements  included in the  Collateral  to the extent set forth
therein to perform  all of its duties  and  obligations  thereunder  to the same
extent as if this  Agreement  had not been  executed,  (b) the  exercise  by the
Administrative Agent of any of its rights hereunder shall not release the Debtor
from any of its  duties  or  obligations  under  the  contracts  and  agreements
included in the  Collateral,  and (c) neither the  Administrative  Agent nor any
Lender shall have any  obligation  or liability  under any of the  contracts and
agreements included in the Collateral by reason of this Agreement, nor shall the
Administrative  Agent  or  any  Lender  be  obligated  to  perform  any  of  the
obligations or duties of the Debtor  thereunder or to take any action to collect
or enforce any claim for payment assigned hereunder.

                                   ARTICLE III

                         Representations and Warranties

         To induce the Administrative Agent to enter into this Agreement and the
Agents and the Lenders to enter into the Loan Agreement,  the Debtor  represents
and warrants to the Administrative Agent that:

         Section  3.1  Corporate  Existence.  The Debtor:  (a) is a  corporation
validly existing, and in good standing under the laws of the jurisdiction of its
incorporation;  (b) has all requisite  corporate  power and authority to own its
assets and carry on its  business as now being or as  proposed to be  conducted;
and (c) is qualified to do business in all  jurisdictions in which the nature of
its business makes such qualification  necessary and where failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Debtor.  The  Debtor  has  the
corporate power and authority to execute,  deliver,  and perform its obligations
under this Agreement and the other Loan Documents to which it is or may become a
party;  provided that Debtor may not be in good standing under the laws of North
Carolina,  and  Debtor  makes no  representations  concerning  the impact of its
status as a North  Carolina  nonprofit  corporation on the  representations  set
forth herein.


<PAGE>


         Section 3.2 Corporate Action; No Breach. The execution,  delivery,  and
performance  by the Debtor of this  Agreement  and the other Loan  Documents  to
which the  Debtor is or may  become a party  and  compliance  with the terms and
provisions  hereof  and  thereof  have been  duly  authorized  by all  requisite
corporate  action on the part of the Debtor and do not and will not (a)  violate
or conflict with, or result in a breach of, or require any consent under (i) the
articles of incorporation or bylaws of the Debtor,  (ii) any material applicable
law, rule, or regulation or any material order, writ,  injunction,  or decree of
any  Governmental  Authority or arbitrator,  or (iii) any material  agreement or
instrument  to which the Debtor is a party or by which it or any of its property
is bound or subject,  or (b)  constitute a material  default  under any material
agreement or  instrument,  or result in the creation or  imposition  of any Lien
(except as provided in Section 2.1 hereof) upon any of the revenues or assets of
the Debtor.

         Section 3.3 Approvals.  No authorization,  approval, or consent of, and
no filing or registration with, any Governmental  Authority or third party is or
will be necessary for the execution,  delivery,  or performance by the Debtor of
this Agreement and the other Loan Documents to which the Debtor is or may become
a party or the validity or enforceability thereof.

         Section 3.4 Enforceability.  This Agreement constitutes,  and the other
Loan Documents to which the Debtor is party,  when delivered,  shall  constitute
legal,  valid, and binding  obligations of the Debtor,  enforceable  against the
Debtor  in  accordance  with  their  respective  terms,  except  as  limited  by
bankruptcy,  insolvency,  or other laws of general  application  relating to the
enforcement of creditors' rights.

         Section  3.5  Title.  The Debtor  is,  and with  respect to  Collateral
acquired  after the date  hereof  the Debtor  will be, the legal and  beneficial
owner of the Collateral free and clear of any Lien,  security interest,  pledge,
claim or other  encumbrance  (except for Liens  permitted  by Section 9.2 of the
Loan  Agreement and liens in favor of the  Refractive  Administrative  Agent (as
hereinafter defined)) or, with respect to the Securities, any right or option on
the part of any Person (other than the Lenders) to purchase or otherwise acquire
the Securities or any part thereof,  except for the security  interests  granted
hereunder,  Liens permitted by Section 9.2 of the Loan  Agreement,  and liens in
favor of the Refractive  Administrative Agent (as hereinafter  defined).  Debtor
has granted  subordinate liens and security interests in the Collateral in favor
of Bank of America, N.A., as Administrative Agent under the Loan Agreement dated
as of the date hereof (the "Refractive  Loan Agreement")  among Prime Refractive
Management, L.L.C., a Delaware limited liability company, Bank of America, N.A.,
as Administrative  Agent (the "Refractive  Administrative  Agent"),  BankBoston,
N.A., as Documentation Agent, and the lenders from time to time party thereto.

         Section 3.6  Accounts.  Unless the Debtor has given the  Administrative
Agent written  notice to the contrary,  whenever the security  interest  granted
hereunder attaches to an Account, the Debtor shall be deemed to have represented
and  warranted  to the  Administrative  Agent as to each and all of its Accounts
that (a) each Account is genuine and in all respects what it purports to be, (b)
each Account represents the legal,  valid, and binding obligation of the account
debtor  evidencing  indebtedness  unpaid and owed by such account debtor arising
out of the  performance  of labor or services by the Debtor or the sale or lease
of goods by the Debtor,  (c) the amount of each Account  represented as owing is
the correct amount  actually and  unconditionally  owing except for normal trade
discounts  granted in the  ordinary  course of  business,  and (d) no Account is
subject to any offset, counterclaim, or other defense.

         Section 3.7 Rule 144 Securities. With respect to all Collateral that is
Securities  which are subject to Rule 144 under the  Securities  Act of 1933, as
such rule and act are amended at the time in question and any successor in whole
or in part thereto,  (a) the Debtor is the  beneficial and record owner thereof,
free and clear of any Liens or transfer restrictions (other than restrictions on
the amount thereof which may be sold, and the manner in which sales may be made,
imposed by such Rule 144), (b) the Debtor acquired such Securities directly from
the  issuer  thereof  more  than  two (2)  years  prior to the  date  hereof  in
transactions not involving any public offering, (c) the Debtor paid the purchase
price  therefor  in cash more than two (2) years prior to the date  hereof,  (d)
since such date of  acquisition,  the Debtor has not had a short position in, or
any put or option to dispose  of,  any  capital  stock of any issuer  thereof or
Securities convertible into capital stock of any issuer thereof, (e) neither the
Debtor, nor any person or entity, the sales of which are required by Rule 144 to
be  aggregated  with the sales of the Debtor,  has sold any capital stock of any
issuer of such Securities  during the period of six (6) months prior to the date
hereof, other than sales pursuant to an effective  registration  statement under
the Securities Act of 1933, as amended,  and (f) to the Debtor's best knowledge,
each issuer of such Securities has timely filed all reports required to be filed
by it under the Securities Exchange Act of 1934, as amended.


<PAGE>


         Section 3.8  Financing  Statements.  No financing  statement,  security
agreement,  or other Lien instrument  covering all or any part of the Collateral
is on file in any public  office,  except as may have been filed in favor of the
Refractive  Administrative  Agent,  any lender under the  Refractive  Agreement,
Administrative  Agent, or any Lender pursuant to this Agreement.  The Debtor has
not within the past five (5) years had a trade name or done  business  under any
name other than its legal name set forth at the beginning of this Agreement.

         Section  3.9  Principal  Place  of  Business.  The  principal  place of
business  and chief  executive  office of the Debtor,  and the office  where the
Debtor  keeps its books and  records,  is located  at the  address of the Debtor
shown on the signature pages of this Agreement.

         Section 3.10 Location of Collateral. All Inventory and Equipment of the
Debtor are located at the places specified on Schedule 3 hereto.  The Debtor has
exclusive  possession  and control of its Inventory and  Equipment.  None of the
Inventory or  Equipment  of the Debtor is  evidenced  by a Document  (including,
without limitation,  a negotiable  document of title). All Instruments,  Chattel
Paper, Securities and certificates of title of the Debtor have been delivered to
the Administrative Agent.

         Section 3.11  Perfection.  Upon the filing of Uniform  Commercial  Code
financing  statements in the jurisdictions listed on Schedule 4 attached hereto,
and upon the  Administrative  Agent's  obtaining  possession  of all  Documents,
Instruments,  Chattel Paper, Securities and certificates of title of the Debtor,
and  upon  the  Administrative  Agent's  obtaining  control  of  all  Investment
Property,  the security  interest in favor of the  Administrative  Agent created
herein will constitute a valid and perfected Lien upon and security  interest in
the  Collateral,  subject  to no equal or prior  Lien,  except as  permitted  by
Section 9.2 of the Loan Agreement.

         Section 3.12 Independent  Investigation.  The Debtor has, independently
and  without  reliance  upon any of the Agents or any Lender and based upon such
documents  and  information  as it has deemed  appropriate,  made its own credit
analysis  and  decision to enter into this  Agreement.  There are no  conditions
precedent to the full  effectiveness  of this Agreement that have not been fully
and permanently satisfied.

         Section  3.13  Litigation.  Except as  disclosed on Schedule 7.5 to the
Loan  Agreement,  there  is  no  litigation,   investigation,   or  governmental
proceeding  threatened  against  the  Debtor or any of its  properties  which if
adversely  determined  would have a material adverse effect on the Collateral or
the financial condition,  operations,  or business of the Borrower, any Material
Subsidiary or the Companies taken as a whole.

         Section 3.14 Benefit to Debtor. The value of the consideration received
and to be received by the Debtor as a result of the Borrower, the Agents and the
Lenders entering into the Loan Agreement and the Debtor executing and delivering
this  Agreement  is  reasonably  worth  at least  as much as the  liability  and
obligation of the Debtor  hereunder,  and such  liability and obligation and the
Borrower's entering into the Loan Agreement have benefited and may reasonably be
expected to benefit the Debtor directly and indirectly.

                                   ARTICLE IV

                                    Covenants

         The Debtor  covenants  and agrees  with the  Administrative  Agent that
until the Secured Indebtedness is paid and performed in full and the Commitments
have terminated:


<PAGE>


         Section 4.1  Encumbrances.  Except as  permitted  by Section 9.2 of the
Loan Agreement,  the Debtor shall not create,  permit,  or suffer to exist,  and
shall defend the  Collateral  against,  any Lien,  security  interest,  or other
encumbrance  on the  Collateral,  and shall  defend the  Debtor's  rights in the
Collateral and the  Administrative  Agent's security  interest in the Collateral
against the claims and demands of all  Persons.  The Debtor  shall do nothing to
impair the rights of the Administrative Agent in the Collateral.

         Section 4.2 Delivery.  Prior to or concurrently  with the execution and
delivery of this Agreement,  Debtor shall deliver to the Administrative Agent to
acknowledge all certificates  identified on Schedule 2 hereto,  with all Chattel
Paper, Instruments and Documents of the Debtor.

         Section 4.3  Modification of Accounts.  The Debtor shall, in accordance
with prudent  business  practices,  endeavor to collect or cause to be collected
from each  account  debtor  under  its  Accounts,  as and when due,  any and all
amounts  owing under such  Accounts.  Without the prior  written  consent of the
Administrative  Agent,  the Debtor shall not (a) grant any  extension of time on
any  Account  for any payment or grant  extensions  of time for  payments on its
Accounts which cause the aggregate amount of all payments extended by the Debtor
on its Accounts during any fiscal year of the Debtor to exceed $150,000.00,  (b)
compromise,  compound,  or  settle  any of the  Accounts  for less than the full
amount thereof; provided,  however, that the Debtor may compromise,  compound or
settle  any  Account  which is an amount  less  than  $50,000.00,  provided  the
aggregate  amount  compromised,  compounded or settled during any fiscal year of
the Debtor shall not exceed  $150,000.00,  (c) release, in whole or in part, any
Person liable for payment of an Account in excess of  $50,000.00,  (d) allow any
credit  or  discount  for  payment  with  respect  to any  Account  in excess of
$50,000.00,  other  than  trade  discounts  granted  in the  ordinary  course of
business;  provided,  however,  that the  aggregate  amount  of all  credits  or
discounts  granted  during  any  fiscal  year of the  Debtor  shall  not  exceed
$150,000.00,  or (e) release any Lien,  security interest,  or guaranty securing
any Account in excess of $50,000.00.

         Section  4.4  Disposition  of  Collateral.  The Debtor  shall not sell,
lease,  assign (by operation of law or otherwise),  or otherwise  dispose of, or
grant any option with respect to, the Collateral or any part thereof without the
prior written consent of the  Administrative  Agent,  except the Debtor may sell
Inventory in the ordinary course of business.

         Section  4.5  Distributions.  If the Debtor  shall  become  entitled to
receive or shall receive any stock certificate  (including,  without limitation,
any certificate representing a stock dividend or distribution in connection with
any reclassification,  increase, or reduction of capital or issued in connection
with any  reorganization),  option or  rights,  whether  as an  addition  to, in
substitution  of, or an exchange for any  Collateral  or  otherwise,  the Debtor
agrees to accept the same as the  Administrative  Agent's  agent and to hold the
same in trust for the Administrative  Agent and to deliver the same forthwith to
the  Administrative  Agent in the  exact  form  received,  with the  appropriate
endorsement of the Debtor when necessary and/or appropriate undated stock powers
duly executed in blank, to be held by the Administrative Agent on its own behalf
and on behalf of Refractive  Administrative  Agent as additional  Collateral for
the Secured Indebtedness,  subject to the terms hereof. Any sums paid upon or in
respect of the  Securities  upon the  liquidation  or  dissolution of the issuer
thereof  shall  be paid  over to the  Administrative  Agent  to be held by it as
additional  Collateral for the Secured Indebtedness subject to the terms hereof;
and in case any  distribution  of capital  shall be made on or in respect of the
Securities  or any  property  shall be  distributed  upon or with respect to the
Securities  pursuant to any  recapitalization or reclassification of the capital
of the issuer thereof or pursuant to any  reorganization  of the issuer thereof,
the property so distributed shall be delivered to the Administrative Agent to be
held by it, as additional  Collateral for the Secured  Indebtedness,  subject to
the terms  hereof.  All sums of money and  property  so paid or  distributed  in
respect of the Securities  that are received by the Debtor shall,  until paid or
delivered  to the  Administrative  Agent,  be held by the  Debtor  in  trust  as
additional security for the Secured Indebtedness.


<PAGE>


         Section 4.6 Further Assurances. At any time and from time to time, upon
the request of the Administrative  Agent, and at the sole expense of the Debtor,
the Debtor  shall  promptly  execute and deliver all such  further  instruments,
agreements,  and  documents and take such further  action as the  Administrative
Agent may  reasonably  deem  necessary  or desirable to preserve and perfect its
security interest in the Collateral and carry out the provisions and purposes of
this  Agreement.  Without  limiting the generality of the foregoing,  the Debtor
shall:  (a)  execute  and  deliver to the  Administrative  Agent such  financing
statements  as the  Administrative  Agent  may from  time to time  require;  (b)
deliver and pledge to the Administrative Agent all Documents (including, without
limitation,  negotiable  documents of title) evidencing  Inventory or Equipment;
(c) deliver and pledge to the  Administrative  Agent all  certificates  of title
required by the Loan Agreement, Instruments and Chattel Paper of the Debtor with
any necessary  endorsements;  and (d) execute and deliver to the  Administrative
Agent such other documents,  instruments,  and agreements as the  Administrative
Agent  may   reasonably   require  to  perfect  and   maintain   the   validity,
effectiveness,  and priority of the Loan  Documents and the Liens intended to be
created thereby.  The Debtor authorizes the Administrative  Agent to file one or
more financing or continuation statements,  and amendments thereto,  relating to
all or any part of the  Collateral  without the  signature  of the Debtor  where
permitted  by  law.  A  carbon,  photographic,  or  other  reproduction  of this
Agreement or of any  financing  statement  covering the  Collateral  or any part
thereof  shall be  sufficient  as a  financing  statement  and may be filed as a
financing statement.

         Section 4.7 Risk of Loss;  Insurance.  The Agents and the Lenders shall
not be responsible for any loss or damage to the  Collateral.  The Debtor shall,
at its own expense,  maintain  insurance  with  financially  sound and reputable
insurance  companies  in such  amounts  and  covering  such  risks as is usually
carried  by  corporations  engaged  in similar  businesses  and  owning  similar
properties  in the same general  areas in which the Debtor  operates  consistent
with past  practices  and to the extent  available  on  commercially  reasonable
terms,   provided  that  in  any  event  the  Debtor  will  maintain   workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance,  professional liability insurance and business interruption insurance
reasonably  satisfactory  to the  Administrative  Agent.  Each insurance  policy
covering  Collateral shall name the  Administrative  Agent as loss payee for the
benefit of the Lenders as its  interest  may appear and shall  provide that such
policy will not be canceled or reduced  without  thirty (30) days prior  written
notice to the Administrative Agent.

         Section  4.8   Inspection   Rights.   The  Debtor   shall   permit  the
Administrative  Agent and each Lender and their  respective  representatives  to
examine, inspect, and audit the Collateral and to examine, inspect, and copy the
Debtor's  books  and  records  at  any  reasonable  time  and  as  often  as the
Administrative Agent or any such Lender may desire. The Administrative Agent and
each Lender may at any time and from time to time  contact  account  debtors and
other  obligors  to verify the  existence,  amounts,  and terms of the  Debtor's
Accounts.

         Section 4.9  Corporate  Changes.  The Debtor shall not change its name,
identity,  or corporate  structure  in any manner that might make any  financing
statement filed in connection with this Agreement  seriously  misleading  unless
the Debtor  shall have given the  Administrative  Agent  thirty  (30) days prior
written  notice  thereof  and shall  have  taken all  action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent to make  each  financing
statement  not seriously  misleading.  The Debtor shall not change its principal
place of business, chief executive office, or the place where it keeps its books
and records unless it shall have given the Administrative Agent thirty (30) days
prior written notice thereof and shall have taken all action  reasonably  deemed
necessary  or  desirable  by the  Administrative  Agent  to cause  its  security
interest in the  Collateral to be perfected  with the priority  required by this
Agreement.

         Section  4.10 Books and  Records;  Information.  The Debtor  shall keep
accurate  and  complete  books and records of the  Collateral  and the  Debtor's
business and financial  condition in accordance with GAAP. The Debtor shall from
time  to  time  at  the  request  of the  Administrative  Agent  deliver  to the
Administrative Agent such information regarding the Collateral and the Debtor as
the Administrative Agent may reasonably request, including,  without limitation,
lists and  descriptions  of the  Collateral  and  evidence of the  identity  and
existence  of the  Collateral.  The Debtor shall mark its records to reflect the
security interest of the Administrative Agent hereunder.


<PAGE>


         Section 4.11      Equipment and Inventory.
                           -----------------------

                  (a) The Debtor shall keep the  Equipment  and Inventory at the
         locations  specified  on  Schedule 3 hereto or,  upon  thirty (30) days
         prior written notice to the Administrative  Agent, at such other places
         within  the  United  States of America  where all  action  required  to
         perfect the  Administrative  Agent's security interest in the Equipment
         and Inventory with the priority  required by this Agreement  shall have
         been taken.

               (b) The Debtor shall  maintain  the  Equipment  and  Inventory in
          accordance with Section 8.3 of the Loan Agreement.

         Section 4.12 Warehouse Receipts Non-Negotiable.  The Debtor agrees that
if any  warehouse  receipt or receipt  in the nature of a  warehouse  receipt is
issued in respect of any of the Collateral, such warehouse receipt or receipt in
the nature  thereof shall not be  "negotiable"  (as such term is used in Section
7.104 of the Uniform  Commercial Code as in effect in any relevant  jurisdiction
or under relevant law).

         Section  4.13 Taxes and  Claims.  The Debtor  shall pay and  discharge,
before the same become  delinquent,  (a) all material  taxes,  assessments,  and
governmental  charges  imposed upon it or upon any of its property,  and (b) all
material  lawful  claims  that,  if unpaid,  might become a Lien upon any of its
property;  provided,  however,  that the Debtor  shall not be required to pay or
discharge  any such  tax,  assessment,  or  governmental  charge  which is being
contested in good faith by proper  proceedings being diligently  pursued and for
which adequate reserves have been established in accordance with GAAP.

         Section  4.14  Compliance  with Laws.  The Debtor  shall  comply in all
material respects with all material applicable laws, rules, regulations, orders,
and decrees of any Governmental Authority or arbitrator.

         Section 4.15 Compliance with Agreements. The Debtor shall comply in all
material respects with all agreements,  contracts, and instruments binding on it
or affecting  its  properties or  businesses,  except where the failure to do so
would not have a material adverse effect on the business,  condition  (financial
or otherwise), operations or properties of the Borrower, any Material Subsidiary
or the Companies (taken as a whole).

         Section  4.16  Notification.  Except as permitted by Section 9.2 of the
Loan Agreement, the Debtor shall promptly notify the Administrative Agent of (a)
any Lien, security interest,  encumbrance, or claim that has attached to or been
made or asserted  against any of the Collateral,  (b) any material change in any
of the Collateral, including, without limitation, any material damage to or loss
of any material portion of the Collateral, (c) the occurrence of any other event
that could have a material  adverse  effect on the  Collateral  or the  security
interest created hereunder, and (d) the occurrence or existence of any Default.

         Section 4.17  Collection of Accounts.  Except as otherwise  provided in
this Section or in any other Loan  Document,  the Debtor shall have the right to
collect  and  receive  payments  on  the  Accounts.   In  connection  with  such
collections,  the Debtor may take (and, at the Administrative Agent's direction,
shall  take)  such  actions  as the  Debtor  or  the  Administrative  Agent  may
reasonably deem necessary or advisable to enforce collection of the Accounts.

         Section 4.18 Additional Securities.  The Debtor shall not consent to or
approve the issuance of any  additional  shares of any class of capital stock of
the issuers of any of the  Securities,  or any securities  convertible  into, or
exchangeable  for, any such shares or any warrants,  options,  rights,  or other
commitments  entitling  any Person to  purchase  or  otherwise  acquire any such
shares.


<PAGE>


         Section 4.19 Provide Information.  The Debtor shall fully cooperate, to
the extent reasonably  requested by the Administrative  Agent, in the completion
of any notice,  form,  schedule,  or other document filed by the  Administrative
Agent  on its  own  behalf  or on  behalf  of  the  Debtor,  including,  without
limitation,  any required notice or statement of beneficial  ownership or of the
acquisition of beneficial ownership of the Securities and any notice of proposed
sale of such  Securities  pursuant to Rule 144 as  promulgated by the Securities
and  Exchange  Commission  (the  "SEC")  under the  Securities  Act of 1933,  as
amended.  Without  limiting the  generality of the  foregoing,  the Debtor shall
furnish  to  the  Administrative   Agent  any  and  all  information  which  the
Administrative  Agent may  reasonably  request for  purposes of any such filing,
regarding the Debtor,  the Securities,  and any issuer of any of the Securities,
and the Debtor shall disclose to the  Administrative  Agent all material adverse
information  known by the Debtor with respect to the operations of any issuer of
any of the Securities.

         Section  4.20  Notification  of Changes in  Beneficial  Ownership.  The
Debtor shall promptly notify the Administrative  Agent of any sale of securities
of any  Subsidiary of the Debtor or by any Person named on the Debtor's Rule 144
questionnaire and shall furnish promptly to the  Administrative  Agent a copy of
any Form 144 filed in respect of any such sale.  In  addition,  if the Debtor or
any other Person named in the Debtor's  Rule 144  questionnaire  shall file with
the  SEC a form  or  other  document  reporting  any  change  in the  beneficial
ownership of the common stock of any Subsidiary of the Debtor,  the Debtor shall
promptly furnish to the Administrative Agent a copy of such form or document.

         Section 4.21  Restriction on Sales after Default.  The Debtor shall not
sell or  suffer  or  permit  any  Person  named  in the  accompanying  Rule  144
questionnaire  to sell  any  shares  of the  same  class  of  securities  as the
Securities at any time after any Event of Default shall have occurred.

         Section  4.22  Fixtures.  For any  Collateral  that is a fixture  or an
accession  which has been  attached  to real  estate or other goods prior to the
perfection of the security  interest  granted in Section 2.1 hereof,  the Debtor
shall furnish to Administrative  Agent, upon demand, a disclaimer of interest in
each such fixture or accession and a consent in writing to the security interest
of Administrative  Agent therein,  signed by all persons and entities having any
interest  in such  fixture or  accession  by virtue of any  interest in the real
estate or other goods to which such fixture or accession has been attached.

         Section 4.23 Notation on Title  Certificates.  If certificates of title
are issued or  outstanding  with  respect to any of the  Collateral,  the Debtor
shall cause the security  interest  granted in Section 2.1 hereof to be properly
noted thereon.

                                    ARTICLE V

                       Rights of the Administrative Agent

         Section  5.1  Power  of  Attorney.   The  Debtor   hereby   irrevocably
constitutes  and  appoints  the  Administrative  Agent and any  officer or agent
thereof,   with   full   power  of   substitution,   as  its  true  and   lawful
attorney-in-fact  with full  irrevocable  power and authority in the name of the
Debtor or in its own name, to take any and all action and to execute any and all
documents and instruments  which the  Administrative  Agent at any time and from
time to time deems reasonably  necessary or desirable to accomplish the purposes
of this  Agreement if an Event of Default shall have occurred and be continuing,
and, without  limiting the generality of the foregoing,  the Debtor hereby gives
the Administrative  Agent the power and right on behalf of the Debtor and in its
own name to do any of the  following  (subject to the rights of the Debtor under
Sections 5.2 and 5.3 hereof),  without notice to or the consent of the Debtor if
an Event of Default shall have occurred and be continuing:


<PAGE>


                  (a) to demand, sue for, collect, or receive in the name of the
         Debtor or in its own name, any money or property at any time payable or
         receivable on account of or in exchange for any of the Collateral  and,
         in connection therewith,  endorse checks,  notes, drafts,  acceptances,
         money  orders,  documents of title,  or any other  instruments  for the
         payment of money under the Collateral or any policy of insurance;

               (b) to pay or  discharge  taxes,  Liens,  or  other  encumbrances
          levied or placed on or threatened against the Collateral;

               (c) to notify post office  authorities  to change the address for
          delivery  of  mail  of the  Debtor  to an  address  designated  by the
          Administrative Agent and to receive, open. and subsequently deliver to
          the Debtor mail addressed to the Debtor; and

                  (d) (i) to direct account debtors and any other parties liable
         for any payment under any of the  Collateral to make payment of any and
         all  monies  due  and  to  become  due   thereunder   directly  to  the
         Administrative  Agent or as the Administrative Agent shall direct; (ii)
         to receive payment of and receipt for any and all monies,  claims,  and
         other  amounts  due and to  become  due at any  time in  respect  of or
         arising out of any Collateral;  (iii) to sign and endorse any invoices,
         freight  or  express  bills,  bills of  lading,  storage  or  warehouse
         receipts, drafts against debtors,  assignments,  proxies, stock powers,
         verifications,  and  notices  in  connection  with  accounts  and other
         documents  relating to the  Collateral;  (vi) to commence and prosecute
         any suit,  action,  or  proceeding  at law or in equity in any court of
         competent  jurisdiction  to collect the  Collateral or any part thereof
         and to enforce  any other  right in respect of any  Collateral;  (v) to
         defend any suit,  action, or proceeding brought against the Debtor with
         respect to any Collateral;  (vi) to settle,  compromise,  or adjust any
         suit,  action,  or  proceeding   described  above  and,  in  connection
         therewith,  to give such  discharges or releases as the  Administrative
         Agent may deem appropriate; (vii) to exchange any of the Collateral for
         other   property  upon  any  merger,   consolidation,   reorganization,
         recapitalization,  or other  readjustment of the issuer thereof and, in
         connection therewith, deposit any of the Collateral with any committee,
         depositary,  transfer agent, registrar, or other designated agency upon
         such terms as the Administrative Agent may determine;  (viii) to add or
         release any guarantor,  indorser,  surety, or other party to any of the
         Collateral;  (ix) to renew,  extend,  or otherwise change the terms and
         conditions of any of the Collateral;  (x) to make, settle,  compromise,
         or  adjust  claims  under  any  insurance  policy  covering  any of the
         Collateral;  (xi) to sell,  transfer,  pledge,  make any agreement with
         respect to or otherwise  deal with any of the  Collateral  as fully and
         completely as though the  Administrative  Agent were the absolute owner
         thereof  for all  purposes,  and to do, at the  Administrative  Agent's
         option and the Debtor's expense, at any time, or from time to time, all
         acts and things  which the  Administrative  Agent  deems  necessary  to
         protect,   preserve,   or   realize   upon  the   Collateral   and  the
         Administrative   Agent's  security  interest  therein;   and  (xii)  to
         complete, execute and file with the SEC one or more notices of proposed
         sale of securities pursuant to Rule 144.

         This power of attorney is a power coupled with an interest and shall be
irrevocable.  Neither the Administrative Agent nor any Lender shall be under any
duty  to  exercise  or  withhold  the  exercise  of any of the  rights,  powers,
privileges,  and options expressly or implicitly  granted to the  Administrative
Agent in this Agreement, and shall not be liable for any failure to do so or any
delay in doing so.  Neither  the  Administrative  Agent nor any Lender  shall be
liable for any act or  omission  or for any error of  judgment or any mistake of
fact or law in its  individual  capacity or in its capacity as  attorney-in-fact
except  acts or  omissions  resulting  from  its  gross  negligence  or  willful
misconduct.  This power of attorney is  conferred  on the  Administrative  Agent
solely to protect,  preserve,  and  realize  upon its  security  interest in the
Collateral. Neither the Administrative Agent nor any Lender shall be responsible
for any decline in the value of the Collateral and shall not be required to take
any steps to preserve rights against prior parties or to protect,  preserve,  or
maintain any security interest or Lien given to secure the Collateral.


<PAGE>


         Section 5.2 Voting  Rights.  Unless and until an Event of Default shall
have  occurred and be  continuing,  the Debtor shall be entitled to exercise any
and all voting rights  pertaining to the  Securities or any part thereof for any
purpose not inconsistent with the terms of this Agreement or the Loan Agreement.
The  Administrative  Agent  shall  execute  and  deliver  to the Debtor all such
proxies  and other  instruments  as the Debtor may  reasonably  request  for the
purpose  of  enabling  the Debtor to  exercise  the  voting  rights  which it is
entitled to exercise pursuant to this Section.

         Section 5.3 Dividends.  Unless and until an Event of Default shall have
occurred and be  continuing,  the Debtor shall be entitled to receive and retain
the dividends on the Securities paid in cash out of earned surplus to the extent
and only to the extent that such dividends are permitted by the Loan Agreement.

         Section 5.4 Setoff,  Property Held by the Lenders.  The  Administrative
Agent and each  Lender  shall  have the right to set off and apply  against  the
Secured Indebtedness,  at any time and without notice to the Debtor, any and all
deposits  (general or special,  time or demand,  provisional  or final) or other
sums at any time  credited  by or owing  from  the  Administrative  Agent or any
Lender to the Debtor  whether or not the  Secured  Indebtedness  is then due. As
additional security for the Secured  Indebtedness,  the Debtor hereby grants the
Administrative  Agent  and  each  Lender  a  security  interest  in  all  money,
instruments,  and other  property  of the  Debtor now or  hereafter  held by the
Administrative Agent or any Lender, including without limitation,  property held
in  safekeeping.  In addition to the  Administrative  Agent's and each  Lender's
right of setoff and as further security for the Secured Indebtedness, the Debtor
hereby  grants to each of them a security  interest in all deposits  (general or
special, time or demand, provisional or final) of the Debtor now or hereafter on
deposit  with or held by any of them and all other sums at any time  credited by
or owing from the any of them to the  Debtor.  The rights  and  remedies  of the
Administrative  Agent and each Lender  hereunder are in addition to other rights
and remedies (including,  without limitation,  other rights of setoff) which any
of them may have.

         Section 5.5  Performance by the Secured Party. If the Debtor shall fail
to  perform  any  covenant  or  agreement  contained  in  this  Agreement,   the
Administrative Agent, may, at the direction of the Required Lenders,  perform or
attempt to perform such  covenant or agreement on behalf of the Debtor.  In such
event, the Debtor shall, at the request of the  Administrative  Agent,  promptly
pay any amount expended by the Administrative  Agent or any Lender in connection
with such  performance  or attempted  performance to the  Administrative  Agent,
together with  interest  thereon at the Default Rate from and including the date
of such  expenditure to but excluding the date such expenditure is paid in full.
Notwithstanding  the  foregoing,   it  is  expressly  agreed  that  neither  the
Administrative  Agent nor any Lender shall have any liability or  responsibility
for the performance of any obligations of the Debtor under this Agreement.

                                   ARTICLE VI

                                     Default

         Section  6.1 Rights  and  Remedies.  If an Event of Default  shall have
occurred and be continuing,  the  Administrative  Agent shall have the following
rights and remedies:


<PAGE>


                  (a) In addition to all other  rights and  remedies  granted to
         the  Administrative  Agent  in  this  Agreement  or in any  other  Loan
         Document or by applicable law, the Administrative  Agent shall have all
         of the rights and remedies of a secured party under the UCC (whether or
         not the UCC applies to the affected  Collateral).  Without limiting the
         generality of the foregoing,  the Administrative  Agent may (i) without
         demand or notice to the Debtor, collect, receive, or take possession of
         the   Collateral   or  any  part  thereof  and  for  that  purpose  the
         Administrative   Agent  may  enter  upon  any  premises  on  which  the
         Collateral is located and remove the Collateral  therefrom or render it
         inoperable,  and/or  (ii)  sell,  lease,  or  otherwise  dispose of the
         Collateral,  or any part  thereof,  in one or more parcels at public or
         private  sale  or  sales,  at the  Administrative  Agent's  offices  or
         elsewhere,  for cash, on credit or for future  delivery,  and upon such
         other  terms  as  the   Administrative   Agent  may  deem  commercially
         reasonable. The Administrative Agent shall have the right at any public
         sale or sales,  and, to the extent  permitted by applicable law, at any
         private sale or sales,  to bid and become a purchaser of the Collateral
         or any part  thereof free of any right or equity of  redemption  on the
         part of the  Debtor,  which  right or  equity of  redemption  is hereby
         expressly  waived and  released by the Debtor.  Upon the request of the
         Administrative Agent, the Debtor shall assemble the Collateral and make
         it available to the Administrative Agent at any place designated by the
         Administrative  Agent that is  reasonably  convenient to the Debtor and
         the  Administrative  Agent.  The Debtor agrees that the  Administrative
         Agent shall not be  obligated  to give more than five (5) days  written
         notice of the time and place of any  public  sale or of the time  after
         which  any  private  sale may take  place and that  such  notice  shall
         constitute  reasonable notice of such matters. The Administrative Agent
         shall  not be  obligated  to make  any sale of  Collateral  if it shall
         determine  not to do so,  regardless of the fact that notice of sale of
         Collateral may have been given. The  Administrative  Agent may, without
         notice or publication,  adjourn any public or private sale or cause the
         same to be adjourned from time to time by  announcement at the time and
         place fixed for sale, and such sale may,  without  further  notice,  be
         made at the time and  place to  which  the same was so  adjourned.  The
         Debtor shall be liable for all expenses of retaking, holding, preparing
         for sale, or the like, and all attorneys' fees, legal expenses, and all
         other costs and expenses  incurred by the  Administrative  Agent or any
         Lender in connection  with the  collection of the Secured  Indebtedness
         and the  enforcement  of the  Administrative  Agent's and the  Lender's
         rights under this  Agreement.  The Debtor  shall remain  liable for any
         deficiency  if the  Proceeds  of any sale or other  disposition  of the
         Collateral are  insufficient  to pay the Secured  Indebtedness in full.
         The  Administrative  Agent and the  Lenders  may  apply the  Collateral
         against  the  Secured  Indebtedness  in such  order  and  manner as the
         Administrative  Agent and the Lenders may elect.  The Debtor waives all
         rights of  marshaling,  valuation,  and  appraisal  in  respect  of the
         Collateral.

                  (b)  The  Administrative  Agent  may  cause  any or all of the
         Collateral  held  by  it  to  be  transferred  into  the  name  of  the
         Administrative Agent or the name or names of the Administrative Agent's
         nominee or nominees.

                  (c) The  Administrative  Agent  may  exercise  or  cause to be
         exercised  all voting,  consensual  and other  powers of  ownership  in
         respect  of  the  Collateral  and  the  Debtor  shall  deliver  to  the
         Administrative   Agent,  if  requested  by  the  Administrative  Agent,
         irrevocable proxies with respect to the Securities in form satisfactory
         to the Administrative Agent.

                  (d) The Administrative  Agent may collect or receive all money
         or  property  at any time  payable  or  receivable  on account of or in
         exchange for any of the Collateral, but shall be under no obligation to
         do so.

                  (e) On any sale of the Collateral, the Administrative Agent is
         hereby  authorized to comply with any  limitation or  restriction  with
         which  compliance  is  necessary,  in the  view  of the  Administrative
         Agent's  counsel,  in order to avoid any violation of applicable law or
         in order to obtain any required approval of the purchaser or purchasers
         by any applicable Governmental Authority.


<PAGE>


                  (f) The Debtor agrees that,  because of the  Securities Act of
         1933,  as  amended,  or any other  laws or  regulations,  and for other
         reasons,   there  may  be  legal  and/or   practical   restrictions  or
         limitations  affecting  the  Administrative  Agent in any  attempts  to
         dispose of certain  portions of the Securities and for the  enforcement
         of their rights. For these reasons,  the Administrative Agent is hereby
         authorized by the Debtor,  but not  obligated,  upon the occurrence and
         during the continuation of an Event of Default, to sell all or any part
         of the Securities at private sale,  subject to investment  letter or in
         any other  manner  which will not require the  Securities,  or any part
         thereof,  to be  registered in accordance  with the  Securities  Act of
         1933, as amended, or the rules and regulations  promulgated thereunder,
         or any other laws or regulations, at a reasonable price at such private
         sale or other  distribution in the manner  mentioned  above. The Debtor
         understands  that  the  Administrative  Agent  may  in  its  discretion
         approach a limited number of potential purchasers and that a sale under
         such  circumstances may yield a lower price for the Securities,  or any
         part or party  thereof,  than would  otherwise  be  obtainable  if such
         collateral  were  either  afforded  to a  larger  number  or  potential
         purchasers, or registered or sold in the open market. The Debtor agrees
         that  such  private  sale  shall  be  deemed  to  have  been  made in a
         commercially  reasonable manner, and that the Administrative  Agent has
         no  obligation  to delay  sale of any  Securities  to permit the issuer
         thereof to register it for public sale under any applicable  federal or
         state  securities  laws. The  Administrative  Agent is  authorized,  in
         connection with any such sale (a) to restrict the  prospective  bidders
         on or  purchasers  of any of the  Securities  to a  limited  number  of
         sophisticated  investors  who will  represent  and agree  that they are
         purchasing  for their own account for investment and not with a view to
         the  distribution  or sale of any of such  Securities and (b) to impose
         such other  limitations or conditions in connection  with any such sale
         as the  Administrative  Agent  reasonably  deems  necessary in order to
         comply with  applicable  law. The Debtor  covenants  and agrees that it
         will execute and deliver such  documents  and take such other action as
         the  Administrative  Agent reasonably deems necessary in order that any
         such sale may be made in compliance  with applicable law. Upon any such
         sale the Administrative  Agent shall have the right to deliver,  assign
         and transfer to the  purchaser  thereof the  Securities  so sold.  Each
         purchaser  at  any  such  sale  shall  hold  the   Securities  so  sold
         absolutely,  free from any claim or right of the  Debtor of  whatsoever
         kind,  including any equity or right of  redemption of the Debtor.  The
         Debtor, to the extent permitted by applicable law, hereby  specifically
         waives all rights of redemption,  stay or appraisal which it has or may
         have under any law now existing or hereafter enacted.

                                   ARTICLE VII

                                  Miscellaneous

         Section 7.1 Indemnification. The Debtor hereby agrees to indemnify each
Agent,  each Lender and each Affiliate  thereof and their  respective  officers,
directors,  employees,  attorneys,  and agents  (collectively  the  "Indemnified
Parties")  from,  and hold each of them  harmless  against,  any and all losses,
liabilities,  claims, damages, penalties, judgments,  disbursements,  costs, and
expenses (including  reasonable attorneys' fees) to which any of them may become
subject  which  directly  or  indirectly   arise  from  or  relate  to  (a)  the
negotiation, execution, delivery, performance, administration, or enforcement of
this  Agreement  or any  other  Loan  Document,  (b)  any  of  the  transactions
contemplated by this Agreement or any other Loan Document, (c) any breach by the
Debtor of any representation,  warranty,  covenant, or other agreement contained
in  this  Agreement  or any  other  Loan  Document,  or (d)  any  investigation,
litigation, or other proceeding,  including,  without limitation, any threatened
investigation, litigation, or other proceeding relating to any of the foregoing,
INCLUDING,  WITHOUT  LIMITATION,  THOSE  ARISING  FROM THE SOLE OR  CONTRIBUTORY
NEGLIGENCE OF ANY INDEMNIFIED PARTY.

         Section 7.2 No Waiver;  Cumulative Remedies.  No failure on the part of
any Agent or the Lender to exercise and no delay in exercising, and no course of
dealing with respect to, any right,  power,  or privilege  under this  Agreement
shall operate as a waiver thereof,  nor shall any single or partial  exercise of
any right,  power,  or  privilege  under this  Agreement  preclude  any other or
further  exercise  thereof  or  the  exercise  of any  other  right,  power,  or
privilege. The rights and remedies provided for in this Agreement are cumulative
and not exclusive of any rights and remedies provided by law.

         Section 7.3  Successors and Assigns.  This  Agreement  shall be binding
upon and inure to the benefit of the Debtor,  the Agents,  the Lenders and their
respective heirs, successors, and assigns, except that the Debtor may not assign
any of its rights or obligations  under this Agreement without the prior written
consent of the Administrative Agent.


<PAGE>


         Section 7.4 Amendment;  Entire Agreement.  THIS AGREEMENT  EMBODIES THE
FINAL,  ENTIRE  AGREEMENT  AMONG THE PARTIES  HERETO AND  SUPERSEDES ANY AND ALL
PRIOR COMMITMENTS,  AGREEMENTS,  REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER
WRITTEN  OR  ORAL,  RELATING  TO  THE  SUBJECT  MATTER  HEREOF  AND  MAY  NOT BE
CONTRADICTED OR VARIED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS OR SUBSEQUENT ORAL
AGREEMENTS OR DISCUSSIONS OF THE PARTIES  HERETO.  THERE ARE NO ORAL  AGREEMENTS
AMONG THE PARTIES  HERETO.  The  provisions of this  Agreement may be amended or
waived only by an instrument in writing signed by the parties hereto.

         Section 7.5 Notices. All notices and other communications  provided for
in this Agreement shall be given or made in accordance with Section 13.11 of the
Loan Agreement to the intended  recipient at the "Address for Notices" specified
below its name on the signature pages hereof,  or, as to any party at such other
address  as shall be  designated  by such  party in a notice to the other  party
given in accordance with this Section.

         Section 7.6  Governing  Law.  THIS  AGREEMENT  SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.

     Section 7.7 Headings. The headings, captions, and arrangements used in this
Agreement are for convenience  only and shall not affect the  interpretation  of
this Agreement.

         Section  7.8   Survival  of   Representations   and   Warranties.   All
representations  and  warranties  made in this  Agreement or in any  certificate
delivered  pursuant  hereto  shall  survive the  execution  and delivery of this
Agreement,  and no  investigation  by any Agent or any Lender  shall  affect the
representations  and  warranties or the right of any Agent or any Lender to rely
upon them.

         Section 7.9 Waiver of Bond. In the event the Administrative Agent seeks
to take  possession  of any or all of the  Collateral by judicial  process,  the
Debtor hereby  irrevocably  waives any bonds and any surety or security relating
thereto  that  may  be  required  by  applicable  law  as an  incident  to  such
possession,  and waives any demand for possession  prior to the  commencement of
any such suit or action.

         Section 7.10  Severability.  Any provision of this  Agreement  which is
prohibited or unenforceable in any jurisdiction  shall, as to such jurisdiction,
be ineffective to the extent of such  prohibition  or  unenforceability  without
invalidating  the  remaining   provisions  of  this  Agreement,   and  any  such
prohibition  or  unenforceability  in any  jurisdiction  shall not invalidate or
render unenforceable such provision in any other jurisdiction.

         Section  7.11  Construction.  The Debtor and the  Administrative  Agent
acknowledge  that each of them has had the  benefit of legal  counsel of its own
choice and has been afforded an  opportunity  to review this  Agreement with its
legal counsel.

     Section  7.12  Obligations  Absolute.   All  rights  and  remedies  of  the
Administrative  Agent  hereunder,  and all obligations of the Debtor  hereunder,
shall be absolute and unconditional irrespective of:

               (a) any lack of validity or  enforceability of the Loan Agreement
          or any  of  the  other  Loan  Documents  or  any  other  agreement  or
          instrument relating to any of the foregoing;

                   (b) any change in the time,  manner,  or place of payment of,
         or in any other term of, all or any of the Secured Indebtedness, any or
         all of the  Obligations,  or any  other  amendment  or waiver of or any
         consent to any  departure  from the Loan  Agreement or any of the other
         Loan Documents;


<PAGE>


               (c) any exchange, release, or nonperfection of any Collateral, or
          any release or amendment or waiver of or consent to any departure from
          any guarantee, for all or any of the Secured Indebtedness; or

                   (d) any other circumstance (other than payment in full of the
         Secured   Indebtedness)  that  might  otherwise  constitute  a  defense
         available to, or a discharge of, the Debtor.

         Section 7.13 Limitations. Notwithstanding any contrary provision, it is
the intention of Debtor,  Lenders, and Administrative Agent that the granting of
the  liens  set  forth in this  Agreement  shall  not  constitute  a  fraudulent
conveyance,   fraudulent  transfer,   or  similar  Laws  applicable  to  Debtor.
Accordingly,   notwithstanding  anything  to  the  contrary  contained  in  this
Agreement or any other agreement or instrument executed in connection  herewith,
granting of liens set forth in this  Agreement  shall be limited to an aggregate
amount  equal  to the  largest  amount  that  would  not  render  such  Debtor's
obligations  hereunder  subject to  avoidance  under  Section  548 of the United
Stated Bankruptcy Code or any comparable provision of any applicable state law.

         Section 7.14 Renewal.  Debtor acknowledges that this Agreement has been
given  in  amendment,   renewal,   restatement  and   confirmation  of  Debtor's
obligations,  covenants,  and  agreements  contained in the  Guarantor  Security
Agreement previously executed by Debtor in favor of Administrative Agent and the
Lenders, dated April 20, 1998, as amended,  confirmed,  and renewed from time to
time (the "Previous Agreement"). Debtor further confirms and agrees that neither
the  execution  of the  Loan  Agreement  or any  other  Loan  Document,  nor the
consummation of the transactions  described therein, shall in any way affect the
liens under the Previous  Agreement,  and the  obligations,  liens, and security
interests  evidenced by the Previous Agreement continue in full force and effect
as modified, amended, and restated by the terms contained herein.

         Section 7.15 Termination. If all of the Secured Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Debtor and in  accordance  with  applicable  provisions  of the Loan  Agreement,
promptly  execute and deliver to the Debtor a proper  instrument or  instruments
acknowledging  the release and termination of the security  interests created by
this  Agreement as the Debtor may reasonably  deem  necessary or desirable,  and
shall duly assign and deliver to the Debtor  (without  recourse  and without any
representation  or warranty)  such of the Collateral as may be in the possession
of the  Administrative  Agent  and has not  previously  been  sold or  otherwise
applied pursuant to this Agreement.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGE TO FOLLOW.


<PAGE>



                                                    Guarantor Security Agreement

         IN WITNESS  WHEREOF,  the Debtor has duly executed this Agreement as of
the day and year first written above.

                                     DEBTOR:

                                                    FASTSTART, INC.,
                                                    a North Carolina corporation

                                                     By: /s/ Teena E. Belcik
                                                              Teena E. Belcik
                                                              Treasurer

                                                 Address for Notices:

                                               1301 Capital of Texas Highway
                                               Suite C-300
                                               Austin, Texas 78746
                                               Attn: Treasurer
                                               Fax Number:  (512) 328-8510
                                               Telephone Number:  (512) 314-4554


























<PAGE>





                                       21

                                                    Guarantor Security Agreement

                                   SCHEDULE 1

                                 MOTOR VEHICLES

None


<PAGE>


                                   SCHEDULE 2

                                   SECURITIES

                                  Pledged Stock

None


<PAGE>


                                   SCHEDULE 3

                             LOCATION OF COLLATERAL

                       Location of Equipment and Inventory

1301 Capital of Texas Highway
Suite C-300

Austin, Travis County, Texas 78746-6550


<PAGE>


                                   SCHEDULE 4

                            JURISDICTIONS FOR FILING

               Jurisdictions for Filing UCC-1 Financing Statements

Texas
North Carolina





                                                    Copyright Security Agreement

                     GUARANTOR COPYRIGHT SECURITY AGREEMENT

         THIS GUARANTOR  COPYRIGHT SECURITY AGREEMENT (the "Agreement") dated as
of January 31,  2000,  is  executed by  LITHOTRIPTERS,  INC.,  a North  Carolina
corporation (the "Debtor"), for the benefit of BANK OF AMERICA, N.A., a national
banking  association  ("B of A"), not in its  individual  capacity but solely as
administrative  agent  for  itself  and  each  of the  other  banks  or  lending
institutions (each, a "Lender" and collectively,  the "Lenders") which is or may
from time to time become a party to the Loan Agreement (as hereinbelow  defined)
(in  such  capacity,   together  with  its  successors  in  such  capacity,  the
"Administrative Agent").

                                R E C I T A L S:

     A. Prime Medical Services,  Inc., a Delaware corporation (the "Borrower"),
B of A as administrative  agent,  BankBoston,  N.A., as documentation agent, and
the Lenders  have entered into that  certain  Fourth  Amended and Restated  Loan
Agreement  dated as of the date hereof,  (as the same may be amended,  restated,
extended,  supplemented  or modified from time to time,  the "Loan  Agreement"),
pursuant to which the Lenders have agreed to make a revolving credit loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Eighty-Six Million and 00/100 Dollars ($86,000,000.00) at any time outstanding.

         B. The Debtor and certain other  guarantors  have executed that certain
Guaranty  Agreement  of  even  date  herewith  (as  the  same  may  be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
the Debtor has  guaranteed to the Agents (as defined in the Loan  Agreement) and
the Lenders the full and complete payment and performance of the Obligations (as
defined in the Loan Agreement).

         C. The Debtor has executed that certain Guarantor Security Agreement of
even date  herewith (as the same may be amended,  supplemented  or modified from
time to time, the "Security Agreement") pursuant to which the Debtor has granted
to the Administrative Agent for the benefit of the Lenders a continuing security
interest in certain personal property of the Debtor.

     D. The Agents and the Lenders have conditioned  their obligations under the
Loan Agreement upon the execution and delivery of this Agreement by the Debtor.

         NOW,  THEREFORE,  in  consideration  of the premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

         SECTION 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         SECTION 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.


<PAGE>





D-737397.1

                                      - 3 -

                                                    Copyright Security Agreement

         SECTION 2. Grant of Security  Interest.  The Debtor hereby  pledges and
grants to the  Administrative  Agent,  for the benefit of the  Lenders,  a first
priority lien on and security interest in all of the Debtor's right,  title, and
interest in and to the following property (the "Copyright Collateral"),  whether
now owned or hereafter arising or acquired,  being all copyrights of the Debtor,
whether statutory or common law, registered or unregistered, now or hereafter in
force throughout the world including,  without  limitation,  all of the Debtor's
right,  title and  interest in and to all  copyrights  registered  in the United
States  Copyright  Office or  anywhere  else in the  world  and also  including,
without limitation,  the copyrights referred to in Item A of Schedule 1 attached
hereto,  and all applications for  registration  thereof,  whether pending or in
preparation,  all copyright licenses,  including each copyright license referred
to in Item B of Schedule 1 attached hereto,  the right to sue for past,  present
and future  infringements  of any of the  foregoing,  all  rights  corresponding
thereto  throughout  the  world,  all  extensions  and  renewals  of  any of the
foregoing,  and all proceeds of the foregoing,  including,  without  limitation,
licenses, royalties, income, payments, claims, damages and proceeds of suit.

         SECTION 3. Secured Indebtedness.  The Copyright Collateral shall secure
the following  obligations,  indebtedness,  and  liabilities  (whether at stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

     (a) the Obligations and the  obligations,  liabilities and  indebtedness of
the Debtor to the Agents and the Lenders under the Guaranty;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the  Collateral (as defined
in the Security Agreement),  collect the obligations described herein and in the
Security Agreement, and enforce this Agreement and the Security Agreement; and

     (c) all extensions, renewals, and modifications of any of the foregoing.

         SECTION 4.  Security  Agreement.  This  Agreement has been executed and
delivered by the Debtor for the purpose of registering the security  interest of
Administrative  Agent  in  the  Copyright  Collateral  with  the  United  States
Copyright Office and corresponding  offices in other countries of the world. The
security interest granted hereby has been granted as a supplement to, and not in
limitation of, the security  interest  granted to  Administrative  Agent for its
benefit  and the  benefit  of the  Lenders  under the  Security  Agreement.  The
Security Agreement (and all rights and remedies of Administrative  Agent and the
Lenders thereunder) shall remain in full force and effect in accordance with its
terms.

         SECTION 5. Termination.  If all of the Secured  Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Debtor and in  accordance  with  applicable  provisions  of the Loan  Agreement,
promptly  execute and deliver to the Debtor a proper  instrument or  instruments
acknowledging  the release and termination of the security  interests created by
this  Agreement as the Debtor may reasonably  deem  necessary or desirable,  and
shall duly assign and deliver to the Debtor  (without  recourse  and without any
representation  or warranty)  such of the Copyright  Collateral as may be in the
possession  of the  Administrative  Agent  and has not  previously  been sold or
otherwise applied pursuant to this Agreement.


<PAGE>


         SECTION 6.  Acknowledgment.  The Debtor does hereby further acknowledge
and affirm that the rights and remedies of Administrative  Agent with respect to
the security interest in the Copyright  Collateral granted hereby are more fully
set  forth  in the  Security  Agreement,  the  terms  and  provisions  of  which
(including  the remedies  provided for  therein) are  incorporated  by reference
herein as if fully set forth herein.

         SECTION  7. Loan  Document,  etc.  This  Agreement  is a Loan  Document
executed  pursuant to the Loan Agreement and shall (unless  otherwise  expressly
indicated herein) be construed,  administered and applied in accordance with the
terms and provisions of the Loan Agreement.

     SECTION 8.  Counterparts.  This Agreement may be executed by parties hereto
in several counterparts, each of which shall be deemed to be an original and all
of which shall constitute together but one and the same agreement.


                     REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGE TO FOLLOW.


<PAGE>





                                                    Copyright Security Agreement

         IN WITNESS  WHEREOF,  the Debtor has duly executed this Agreement as of
the day and year first written above.

                                                     LITHOTRIPTERS, INC.



                                                 By: /s/ Teena E. Belcik
                                                           Teena E. Belcik
                                                           Treasurer

                                             Address: 2008 Litho Place
                                                      Fayetteville, NC 28304
                                                      Attention: Treasurer


<PAGE>





                          Copyright Security Agreement

         IN WITNESS  WHEREOF,  B of A has duly executed this Agreement as of the
day and year first written above.

                                                     BANK OF AMERICA, N.A.,
                                                       as Administrative Agent

                                                     By: /s/ Daniel H. Penkar
                                                           Daniel H. Penkar
                                                           Senior Vice President

                                  Address:       515 Congress Avenue, 11th Floor
                                                 Austin, Texas 78701
                                                 Attention:     Wade Morgan


<PAGE>







                                                    Copyright Security Agreement

                                   SCHEDULE 1

Item A:  Registered Copyrights

Title                                                         Registration No.
- -----                                                         ---------------

Generic Quality Assurance Plan: Lithotripsy Unit              TX 3124352

Generic Hospital Lithostar Service Quality Assessment Plan    TX 3124351

Lithotripters, Inc., Quality Assurance Plan                   TX 2792856

Introduction to the Lithostar and Guide to its Use            TX 2670895





Item B: Copyright License Rights

Title                                                      Licensor

Scheduling, Billing and Accounts
         Receivable Computer System                  Omni-Medical Systems, Inc.

QA Outcome Analysis Computer System                  MEDformatics, Inc.

<PAGE>


                          Copyright Security Agreement

                     GUARANTOR COPYRIGHT SECURITY AGREEMENT

         THIS GUARANTOR  COPYRIGHT SECURITY AGREEMENT (the "Agreement") dated as
of January 31,  2000,  is  executed by  LITHOTRIPTERS,  INC.,  a North  Carolina
corporation (the "Debtor"), for the benefit of BANK OF AMERICA, N.A., a national
banking  association  ("B of A"), not in its  individual  capacity but solely as
administrative  agent  for  itself  and  each  of the  other  banks  or  lending
institutions (each, a "Lender" and collectively,  the "Lenders") which is or may
from time to time become a party to the Loan Agreement (as hereinbelow  defined)
(in  such  capacity,   together  with  its  successors  in  such  capacity,  the
"Administrative Agent").

                                R E C I T A L S:
                                 - - - - - - - -

         A.. Prime Refractive  Management,  L.L.C., a Delaware limited liability
company (the "Borrower"), B of A, as administrative agent, BankBoston,  N.A., as
documentation  agent,  and the  Lenders  have  entered  into that  certain  Loan
Agreement  dated as of the date hereof,  (as the same may be amended,  restated,
extended,  supplemented  or modified from time to time,  the "Loan  Agreement"),
pursuant to which the Lenders have agreed to make an advancing  term loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Fourteen Million and 00/100 Dollars ($14,000,000.00).

         B. The Debtor and certain other  guarantors  have executed that certain
Guaranty  Agreement  of  even  date  herewith  (as  the  same  may  be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
the Debtor has  guaranteed to the Agents (as defined in the Loan  Agreement) and
the Lenders the full and complete payment and performance of the Obligations (as
defined in the Loan Agreement).

         C. The Debtor has executed that certain Guarantor Security Agreement of
even date  herewith (as the same may be amended,  supplemented  or modified from
time to time, the "Security Agreement") pursuant to which the Debtor has granted
to the Administrative Agent for the benefit of the Lenders a continuing security
interest in certain personal property of the Debtor.

     D. The Agents and the Lenders have conditioned  their obligations under the
Loan Agreement upon the execution and delivery of this Agreement by the Debtor.

         NOW,  THEREFORE,  in  consideration  of the premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

         SECTION 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         SECTION 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.


<PAGE>






                                      - 3 -

                          Copyright Security Agreement


<PAGE>


         SECTION 2. Grant of Security  Interest.  The Debtor hereby  pledges and
grants to the  Administrative  Agent, for the benefit of the Lenders,  a lien on
and security  interest in all of the Debtor's right,  title, and interest in and
to the following  property (the  "Copyright  Collateral"),  whether now owned or
hereafter  arising or  acquired,  being all  copyrights  of the Debtor,  whether
statutory or common law,  registered or unregistered,  now or hereafter in force
throughout the world including,  without limitation,  all of the Debtor's right,
title and  interest in and to all  copyrights  registered  in the United  States
Copyright  Office or  anywhere  else in the world  and also  including,  without
limitation,  the copyrights referred to in Item A of Schedule 1 attached hereto,
and  all  applications  for   registration   thereof,   whether  pending  or  in
preparation,  all copyright licenses,  including each copyright license referred
to in Item B of Schedule 1 attached hereto,  the right to sue for past,  present
and future  infringements  of any of the  foregoing,  all  rights  corresponding
thereto  throughout  the  world,  all  extensions  and  renewals  of  any of the
foregoing,  and all proceeds of the foregoing,  including,  without  limitation,
licenses,  royalties,  income,  payments,  claims, damages and proceeds of suit.
Such  lien  and  security  interest  shall be  subordinate  only to the lien and
security  interest granted in favor of Bank of America,  N.A., as Administrative
Agent ("Prime  Administrative Agent") under the Fourth Amended and Restated Loan
Agreement dated as of the date hereof among Prime Medical  Services,  Inc., Bank
of America,  N.A., as administrative agent,  BankBoston,  N.A., as documentation
agent, and the lenders from time to time thereunder.

         SECTION 3. Secured Indebtedness.  The Copyright Collateral shall secure
the following  obligations,  indebtedness,  and  liabilities  (whether at stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

     (a) the Obligations and the  obligations,  liabilities and  indebtedness of
the Debtor to the Agents and the Lenders under the Guaranty;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the  Collateral (as defined
in the Security Agreement),  collect the obligations described herein and in the
Security Agreement, and enforce this Agreement and the Security Agreement; and

     (c) all extensions, renewals, and modifications of any of the foregoing.

         SECTION 4.  Security  Agreement.  This  Agreement has been executed and
delivered by the Debtor for the purpose of registering the security  interest of
Administrative  Agent  in  the  Copyright  Collateral  with  the  United  States
Copyright Office and corresponding  offices in other countries of the world. The
security interest granted hereby has been granted as a supplement to, and not in
limitation of, the security  interest  granted to  Administrative  Agent for its
benefit  and the  benefit  of the  Lenders  under the  Security  Agreement.  The
Security Agreement (and all rights and remedies of Administrative  Agent and the
Lenders thereunder) shall remain in full force and effect in accordance with its
terms.

         SECTION 5. Termination.  If all of the Secured  Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Debtor and in  accordance  with  applicable  provisions  of the Loan  Agreement,
promptly  execute and deliver to the Debtor a proper  instrument or  instruments
acknowledging  the release and termination of the security  interests created by
this  Agreement as the Debtor may reasonably  deem  necessary or desirable,  and
shall duly assign and deliver to the Debtor  (without  recourse  and without any
representation  or warranty)  such of the Copyright  Collateral as may be in the
possession  of the  Administrative  Agent  and has not  previously  been sold or
otherwise applied pursuant to this Agreement.


<PAGE>


         SECTION 6.  Acknowledgment.  The Debtor does hereby further acknowledge
and affirm that the rights and remedies of Administrative  Agent with respect to
the security interest in the Copyright  Collateral granted hereby are more fully
set  forth  in the  Security  Agreement,  the  terms  and  provisions  of  which
(including  the remedies  provided for  therein) are  incorporated  by reference
herein as if fully set forth herein.

         SECTION  7. Loan  Document,  etc.  This  Agreement  is a Loan  Document
executed  pursuant to the Loan Agreement and shall (unless  otherwise  expressly
indicated herein) be construed,  administered and applied in accordance with the
terms and provisions of the Loan Agreement.

     SECTION 8.  Counterparts.  This Agreement may be executed by parties hereto
in several counterparts, each of which shall be deemed to be an original and all
of which shall constitute together but one and the same agreement.


                     REMAINDER OF PAGE INTENTIONALLY BLANK.
                            SIGNATURE PAGE TO FOLLOW.


<PAGE>





                          Copyright Security Agreement

         IN WITNESS  WHEREOF,  the Debtor has duly executed this Agreement as of
the day and year first written above.

                           LITHOTRIPTERS, INC.



                           By: /s/ Teena E. Belcik
                                 Teena E. Belcik

                                 Treasurer

                                 Address:       2008 Litho Place
                                                Fayetteville, NC 28304
                                                Attention:     Treasurer


<PAGE>





                          Copyright Security Agreement

         IN WITNESS  WHEREOF,  B of A has duly executed this Agreement as of the
day and year first written above.

                             BANK OF AMERICA, N.A.,
                             as Administrative Agent

                             By:/s/ Daniel H. Penkar
                                 Daniel H. Penkar

                                 Senior Vice President

                                 Address:       515 Congress Avenue, 11th Floor
                                                Austin, Texas 78701
                                                Attention:     Wade Morgan


<PAGE>







                          Copyright Security Agreement

                                                     SCHEDULE 1

Item A:  Registered Copyrights

Title                                                       Registration No.
- -----                                                      ----------------

Generic Quality Assurance Plan: Lithotripsy Unit              TX 3124352

Generic Hospital Lithostar Service Quality Assessment Plan    TX 3124351

Lithotripters, Inc., Quality Assurance Plan                   TX 2792856

Introduction to the Lithostar and Guide to its Use            TX 2670895





Item B: Copyright License Rights

Title                                                         Licensor

Scheduling, Billing and Accounts Receivable
         Computer System                              Omni-Medical Systems, Inc.

QA Outcome Analysis Computer System                   MEDformatics, Inc.





                               GUARANTY AGREEMENT

         WHEREAS,  PRIME  REFRACTIVE  MANAGEMENT,  L.L.C.,  a  Delaware  limited
liability company  ("Borrower"),  has entered into a Loan Agreement of even date
herewith with certain banks and other lending institutions which are or may from
time to time become signatories  thereto,  BANKBOSTON,  N.A., a national banking
association,  as documentation  agent for itself and the other Lenders,  BANK OF
AMERICA,  N.A. ("B of A"), a national  banking  association,  as  administrative
agent for itself and the other  Lenders  (in such  capacity,  together  with its
successors in such capacity, the "Administrative Agent"),  pursuant to which the
Lenders have agreed to make an advancing term loan to the Borrower with advances
thereunder not to exceed an aggregate  principal  amount of Fourteen Million and
00/100 Dollars at any time outstanding ($14,000,000.00) (such Loan Agreement, as
may be amended, extended, restated,  supplemented or modified from time to time,
the "Loan  Agreement");  terms  defined in the Loan  Agreement and not otherwise
defined herein are used herein as defined therein; and

         WHEREAS,  the Agents and the Lenders have conditioned their obligations
under  the  Loan  Agreement  upon  the  execution  and  delivery  by  Guarantors
(hereinafter defined) of this Guaranty Agreement (this "Guaranty");

         NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which  are  hereby  acknowledged,  each  of  the  undersigned  (individually,  a
"Guarantor" and collectively,  the "Guarantors"),  hereby jointly and severally,
irrevocably and  unconditionally  guarantees to the Agents,  and to the Lenders,
the full and prompt  payment  and  performance  of the  Guaranteed  Indebtedness
(hereinafter defined), this Guaranty being upon the following terms:

         1 . The term "Guaranteed Indebtedness", as used herein means all of the
Obligations  and shall include any and all  post-petition  interest and expenses
(including  attorneys'  fees)  whether  or not  allowed  under  any  bankruptcy,
insolvency, or other similar law.

         2. This Guaranty  shall be an absolute,  continuing,  irrevocable,  and
unconditional  guaranty  of  payment  and  performance,  and not a  guaranty  of
collection,  and each Guarantor shall remain liable on its obligations hereunder
until the payment and  performance  in full of the Guaranteed  Indebtedness  and
termination of the Commitments. No set-off, counterclaim, recoupment, reduction,
or  diminution  of any  obligation,  or any defense of any kind or nature  which
Borrower may have against any Agent, any Lender or any other party, or which any
Guarantor may have against Borrower or any other party (other than the Agents or
any  Lender),  shall be  available  to, or shall be asserted  by, any  Guarantor
against  any  Agent,  any  Lender or any  subsequent  holder  of the  Guaranteed
Indebtedness   or  any  part  thereof  or  against  payment  of  the  Guaranteed
Indebtedness or any part thereof.


<PAGE>







                                        7



         3. Notwithstanding any contrary provision,  it is the intention of each
Guarantor,  Lenders,  and Agents that the amount of the Guaranteed  Indebtedness
guaranteed by each  Guarantor by this  Guaranty  shall be, but not in excess of,
the maximum amount permitted by fraudulent  conveyance,  fraudulent transfer, or
similar Laws applicable to such Guarantor. Accordingly, notwithstanding anything
to the contrary  contained in this Guaranty or any other agreement or instrument
executed in connection  with the payment of any of the Guaranteed  Indebtedness,
the amount of the  Guaranteed  Indebtedness  guaranteed by any Guarantor by this
Guaranty  shall be limited to an aggregate  amount  equal to the largest  amount
that  would  not  render  such  Guarantor's  obligations  hereunder  subject  to
avoidance  under  Section  548 of  the  United  States  Bankruptcy  Code  or any
comparable provision of any applicable state law.


<PAGE>


         4. If any  Guarantor  becomes  liable  for any  indebtedness  owing  by
Borrower  to any Agent or any Lender by  endorsement  or  otherwise,  other than
under this  Guaranty,  such  liability  shall not be in any manner  impaired  or
affected hereby, and the rights of the Agents and the Lenders hereunder shall be
cumulative  of any and all other rights that the Agents and the Lenders may ever
have  against  such  Guarantor.  The exercise by the Agents or any Lender of any
right or remedy hereunder or under any other instrument, or at law or in equity,
shall not preclude the  concurrent or subsequent  exercise of any other right or
remedy.

         5. In the event of default by Borrower in payment or performance of the
Guaranteed Indebtedness,  or any part thereof, when such Guaranteed Indebtedness
becomes due,  whether by its terms, by  acceleration,  or otherwise,  Guarantors
shall promptly pay the amount due thereon to the  Administrative  Agent, for the
benefit of the Lenders,  upon demand in lawful  currency of the United States of
America and it shall not be necessary for the Administrative  Agent, in order to
enforce  such  payment by  Guarantors,  first to  institute  suit or exhaust its
remedies against Borrower or others liable on such Guaranteed  Indebtedness,  or
to enforce any rights against any collateral which shall ever have been given to
secure such Guaranteed Indebtedness.

         6. If  acceleration  of the time for  payment of any amount  payable by
Borrower  under  the  Guaranteed  Indebtedness  is stayed  upon the  insolvency,
bankruptcy, or reorganization of Borrower, all such amounts otherwise subject to
acceleration under the terms of the Guaranteed Indebtedness shall nonetheless be
payable by Guarantors hereunder forthwith on demand by the Administrative Agent.


<PAGE>


         7.  Each  Guarantor  hereby  agrees  that its  obligations  under  this
Guaranty shall not be released,  discharged,  diminished,  impaired, reduced, or
affected for any reason or by the  occurrence of any event,  including,  without
limitation,  one or more of the following events,  whether or not with notice to
or the consent of such  Guarantor:  (a) the taking or accepting of collateral as
security for any or all of the  Guaranteed  Indebtedness  or the sale,  release,
surrender,  exchange,  or  subordination  of any  collateral  now  or  hereafter
securing any or all of the Guaranteed  Indebtedness;  (b) any partial release of
the  liability of any  Guarantor  hereunder,  or the full or partial  release of
Borrower or any other  guarantor from liability for any or all of the Guaranteed
Indebtedness;  (c) the dissolution,  insolvency,  or bankruptcy of Borrower, any
Guarantor,  or any other  party at any time liable for the payment of any or all
of the  Guaranteed  Indebtedness;  (d)  any  renewal,  extension,  modification,
waiver, amendment, or rearrangement of any or all of the Guaranteed Indebtedness
or any instrument,  document,  or agreement  evidencing,  securing, or otherwise
relating  to any or all of the  Guaranteed  Indebtedness;  (e)  any  adjustment,
indulgence,  forbearance,  waiver, settlement, or compromise that may be granted
or given by any Agent or any Lender to  Borrower,  any  Guarantor,  or any other
party  ever  liable  for  any or all of the  Guaranteed  Indebtedness;  (f)  the
subordination  of the payment of all or any part of the Guaranteed  Indebtedness
to the payment of any obligations, indebtedness, or liabilities which may be due
or become  due to any of the  Agents,  any of the  Lenders  or  others;  (g) the
application of any deposit balance,  fund, payment,  collections through process
of law or otherwise,  or other  collateral of Borrower to the  satisfaction  and
liquidation of the  indebtedness  or obligations of Borrower to Agents or any of
the Lenders, if any, not guaranteed under this Guaranty;  (h) the application of
any sums paid to any of the Agents or any of the Lenders by any  Guarantor,  any
other guarantor of all or any part of the Guaranteed  Indebtedness,  Borrower or
others to the Guaranteed  Indebtedness in such order and manner as any Agent may
determine  in  accordance  with  the Loan  Agreement;  (i) any  neglect,  delay,
omission,  failure,  or refusal of any Agent or any Lender to take or  prosecute
any  action  for the  collection  of any of the  Guaranteed  Indebtedness  or to
foreclose or take or prosecute  any action in  connection  with any  instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (j) the unenforceability or invalidity of any or
all of the Guaranteed Indebtedness or of any instrument,  document, or agreement
evidencing,  securing,  or  otherwise  relating to any or all of the  Guaranteed
Indebtedness; (k) any payment by Borrower or any other party to any Agent or any
Lender  is held to  constitute  a  preference  under  applicable  bankruptcy  or
insolvency law or if for any other reason any Agent or any Lender is required to
refund any payment or pay the amount thereof to someone else; (l) the settlement
or compromise of any of the Guaranteed  Indebtedness;  (m) the non-perfection of
any  security   interest  or  lien  securing  any  or  all  of  the   Guaranteed
Indebtedness;  (n) any impairment of any  collateral  securing any or all of the
Guaranteed Indebtedness;  (o) the failure of any Agent or any Lender to sell any
collateral securing any or all of the Guaranteed  Indebtedness in a commercially
reasonable  manner  or as  otherwise  required  by law;  (p) any  change  in the
corporate  existence,  structure,  or  ownership  of  Borrower;  (q)  any  other
circumstance  which  might  otherwise  constitute  a  defense  available  to, or
discharge  of,  Borrower;  (r) the  unenforceability  of all or any  part of the
Guaranteed  Indebtedness  against  Borrower  by  reason  of the  fact  that  the
Guaranteed  Indebtedness  exceeds the amount  permitted  by law;  (s) the act of
creating all or any part of the Guaranteed  Indebtedness  is ultra vires; or (t)
the officers  creating all or any part of the Guaranteed  Indebtedness  acted in
excess of their authority.

     8. Each  Guarantor  hereby  represents  and  warrants to the Agents and the
Lenders the following:

               (a) This Guaranty may reasonably be expected to benefit, directly
          or indirectly,  each  Guarantor.

               (b)  Each  Guarantor  is  familiar  with,  and has  independently
          reviewed the books and records regarding,  the financial  condition of
          Borrower  and is  familiar  with the  value of any and all  collateral
          intended  to be  security  for the  payment  of all or any part of the
          Guaranteed  Indebtedness.  However,  no  Guarantor  is relying on such
          financial  condition or collateral as an inducement to enter into this
          Guaranty.

                  (c) Each  Guarantor has adequate means to obtain from Borrower
         on a continuing basis information concerning the financial condition of
         Borrower,  and no  Guarantor is relying on the Agents or the Lenders to
         provide such information to any Guarantor either now or in the future.

                  (d) Each  Guarantor  has the power and  authority  to execute,
         deliver, and perform this Guaranty and any other agreements executed by
         such Guarantor contemporaneously herewith, and the execution, delivery,
         and performance of this Guaranty and any other  agreements  executed by
         each Guarantor  contemporaneously  herewith do not and will not violate
         (i) any agreement or  instrument to which any Guarantor is a party,  or
         (ii) any law, rule, regulation,  or order of any Governmental Authority
         to which any Guarantor is subject.

                  (e) Neither the Agents,  the Lenders,  nor any other party has
         made any  representation,  warranty,  or statement to any  Guarantor in
         order to induce any Guarantor to execute this Guaranty.

                  (f) The financial  statements and other financial  information
         regarding Guarantors heretofore and hereafter delivered to any Agent or
         any Lender are and shall be true and correct in all  material  respects
         and fairly present the financial position of Guarantors as of the dates
         thereof,  and no material  adverse change has occurred in the financial
         condition of any Guarantor as reflected in those financial disclosures.

                  (g) As of the date  hereof,  and after  giving  effect to this
         Guaranty and the obligations  evidenced  hereby,  (i) each Guarantor is
         and will be Solvent (to the extent  necessary,  taking into account any
         rights of contribution,  reimbursement and subrogation),  (ii) the fair
         saleable value of each Guarantor's  assets exceeds and will continue to
         exceed  its  liabilities  (both  fixed  and  contingent),   (iii)  each
         Guarantor  is and  will  continue  to be able to pay its  debts as they
         mature,  and  (iv)  each  Guarantor  has  and  will  continue  to  have
         sufficient capital to carry on its business and all businesses in which
         it is about to engage.


<PAGE>


               (h) All  representations and warranties about each Guarantor made
          in the Loan Agreement are true and correct.

         9. Each Guarantor  covenants and agrees that, as long as the Guaranteed
Indebtedness or any part thereof is outstanding or any Lender has any Commitment
under the Loan Agreement:

                  (a) No Guarantor shall, so long as its obligations  under this
         Guaranty  continue,  transfer  or pledge  any  material  portion of its
         assets for less than full and adequate consideration.

                  (b)   Each   Guarantor   shall   promptly   furnish   to   the
         Administrative  Agent at any time and from time to time such  financial
         statements and other financial  information as the Administrative Agent
         may require,  in form and substance  satisfactory to the Administrative
         Agent.

                  (c) Each Guarantor  shall comply with all terms and provisions
         of the Loan Documents that apply to such Guarantor.

                  (d) Each Guarantor  shall promptly  inform the  Administrative
         Agent of (i) any litigation or governmental  investigation against such
         Guarantor  or  affecting  any  security  for  all  or any  part  of the
         Guaranteed   Indebtedness   or  this  Guaranty   which,  if  determined
         adversely,  might have a material  adverse  effect  upon the  financial
         condition  of such  Guarantor  or upon such  security  or might cause a
         default under any of the Loan Documents,  (ii) any claim or controversy
         which  might  become the  subject of such  litigation  or  governmental
         investigation,  and (iii) any material  adverse change in the financial
         condition of Guarantor.

         10. (a) Each Guarantor hereby agrees that the Subordinated Indebtedness
(hereinafter defined) shall be subordinate and junior in right of payment to the
prior payment in full of all Guaranteed Indebtedness,  and each Guarantor hereby
assigns the  Subordinated  Indebtedness  to the  Administrative  Agent,  for the
benefit of the Lenders, as security for the Guaranteed Indebtedness. If any sums
shall be paid to any  Guarantor  by  Borrower  or any other  person or entity on
account of the  Subordinated  Indebtedness,  such sums shall be held in trust by
such Guarantor for the benefit of the  Administrative  Agent and shall forthwith
be paid to the  Administrative  Agent  without  affecting  the  liability of any
Guarantor under this Guaranty and may be applied by the Administrative Agent and
the Lenders against the Guaranteed  Indebtedness in such order and manner as the
Administrative  Agent and the Lenders may  determine  in their sole  discretion.
Upon the request of the  Administrative  Agent,  each  Guarantor  shall execute,
deliver,  and endorse to the Administrative Agent such documents and instruments
as the Administrative  Agent may request to perfect,  preserve,  and enforce its
rights  hereunder.  For  purposes  of  this  Guaranty,  the  term  "Subordinated
Indebtedness" means all indebtedness,  liabilities,  and obligations of Borrower
to any Guarantor,  whether such indebtedness,  liabilities,  and obligations now
exist or are hereafter incurred or arise, or whether the obligations of Borrower
thereon are direct, indirect, contingent, primary, secondary, several, joint and
several,   or  otherwise,   and  irrespective  of  whether  such   indebtedness,
liabilities,  or obligations are evidenced by a note, contract, open account, or
otherwise,  and  irrespective  of the  person or  persons  in whose  favor  such
indebtedness, obligations, or liabilities may, at their inception, have been, or
may hereafter be created, or the manner in which they have been or may hereafter
be acquired by any Guarantor.


<PAGE>


                  (b) Each  Guarantor  agrees  that any and all liens,  security
interests, judgment liens, charges, or other encumbrances upon Borrower's assets
securing payment of any Subordinated  Indebtedness  shall be and remain inferior
and  subordinate  to any and all  liens,  security  interests,  judgment  liens,
charges,  or other  encumbrances  upon Borrower's assets securing payment of the
Guaranteed  Indebtedness  or  any  part  thereof,  regardless  of  whether  such
encumbrances  in favor of any Guarantor or the  Administrative  Agent  presently
exist or are hereafter created or attached. Without the prior written consent of
the Lenders,  no Guarantor  shall (i) file suit against  Borrower or exercise or
enforce  any  other  creditor's  right it may  have  against  Borrower,  or (ii)
foreclose, repossess, sequester, or otherwise take steps or institute any action
or  proceedings   judicial  or  otherwise,   including  without  limitation  the
commencement  of, or joinder  in, any  liquidation,  bankruptcy,  rearrangement,
debtor's  relief or  insolvency  proceeding)  to  enforce  any  liens,  security
interests,  collateral  rights,  judgments  or  other  encumbrances  held by any
Guarantor on assets of Borrower.

                  (c)   In  the   event   of   any   receivership,   bankruptcy,
reorganization,  rearrangement,  debtor's relief, or other insolvency proceeding
involving Borrower as debtor,  the Administrative  Agent shall have the right to
prove and vote any claim  under the  Subordinated  Indebtedness  and to  receive
directly from the  receiver,  trustee or other court  custodian  all  dividends,
distributions,  and payments made in respect of the  Subordinated  Indebtedness.
The  Administrative  Agent  and  the  Lenders  may  apply  any  such  dividends,
distributions,  and payments  against the Guaranteed  Indebtedness in such order
and manner as the  Administrative  Agent and the Lenders may  determine in their
sole discretion.

                  (d) Each Guarantor agrees that all promissory notes,  accounts
receivable, ledgers, records, or any other evidence of Subordinated Indebtedness
shall contain a specific written notice thereon that the indebtedness  evidenced
thereby is subordinated under the terms of this Guaranty.

         11. Each  Guarantor  waives (a)  promptness,  diligence,  and notice of
acceptance  of this  Guaranty  and notice of the  incurring  of any  obligation,
indebtedness,  or  liability  to which  this  Guaranty  applies or may apply and
waives presentment for payment, notice of nonpayment, protest, demand, notice of
protest,  notice of  intent to  accelerate,  notice of  acceleration,  notice of
dishonor,  diligence in enforcement,  and indulgences of every kind, and (b) the
taking  of any other  action  by the  Administrative  Agent,  including  without
limitation,  giving any notice of default or any other  notice to, or making any
demand on,  Borrower,  any other  guarantor of all or any part of the Guaranteed
Indebtedness  or any other party.  To the maximum extent lawful,  each Guarantor
waives all rights by which it might be  entitled  to require  suit on an accrued
right of action in  respect  of any  Guaranteed  Indebtedness  or  require  suit
against  Borrower  or  others,  whether  arising  under  ss.  34.02 of the Texas
Business  and  Commerce  Code,  as  amended  (regarding  its  right  to  require
Administrative  Agent or Lenders  to sue  Borrower  on  accrued  right of action
following its written notice to Administrative Agent or Lenders),  ss. 17.001 of
the Texas Civil Practice and Remedies Code, as amended (allowing suit against it
without suit  against  Borrower,  but  precluding  entry of judgment  against it
before entry of judgment against Borrower),  Rule 31 of the Texas Rules of Civil
Procedure,  as  amended  (requiring  Administrative  Agent  or  Lenders  to join
Borrower in any suit  against it unless  judgment  has been  previously  entered
against Borrower), or otherwise.

         12. In addition  to any other  waivers,  agreements  and  covenants  of
Guarantors set forth herein,  each Guarantor  hereby further waives and releases
all claims,  causes of action,  defenses  and offsets for any act or omission of
the Administrative Agent, its directors, officers, employees, representatives or
agents in  connection  with the  Administrative  Agent's  administration  of the
Guaranteed   Indebtedness,   except  for  the  Administrative   Agent's  willful
misconduct and gross negligence.

         13. This Guaranty shall  continue to be effective or be reinstated,  as
the case may be, if at any time any payment of all or any part of the Guaranteed
Indebtedness  is  rescinded  or must  otherwise  be returned by any Agent or any
Lender upon the  insolvency,  bankruptcy,  or  reorganization  of Borrower,  any
Guarantor,   any  other   guarantor  of  all  or  any  part  of  the  Guaranteed
Indebtedness, or otherwise, all as though such payment had not been made.


<PAGE>


         14. Any acknowledgment or new promise,  whether by payment of principal
or  interest  or  otherwise  and  whether  by  Borrower  or  others   (including
Guarantors),  with respect to any of the Guaranteed  Indebtedness  shall, if the
statute of  limitations  in favor of any  Guarantor  against the  Administrative
Agent or any  Lender  shall  have  commenced  to run,  toll the  running of such
statute of limitations  and, if the period of such statute of limitations  shall
have expired, prevent the operation of such statute of limitations.

         15. This  Guaranty is for the benefit of the Agents and the Lenders and
their  respective  successors and assigns,  and in the event of an assignment of
the  Guaranteed  Indebtedness,  or any part  thereof,  the rights  and  benefits
hereunder,  to the extent  applicable to the  indebtedness  so assigned,  may be
transferred  with  such  indebtedness.  This  Guaranty  is  binding  not only on
Guarantors, but on each Guarantor's successors and assigns.

         16.  Each  Guarantor  recognizes  that the Agents and the  Lenders  are
relying upon this Guaranty and the  undertakings of each Guarantor  hereunder in
making  extensions  of credit to Borrower  under the Loan  Agreement and further
recognizes  that the  execution  and  delivery  of this  Guaranty  is a material
inducement  to the Agents and the Lenders in entering  into the Loan  Agreement.
Each  Guarantor  hereby  acknowledges  that there are no  conditions to the full
effectiveness of this Guaranty.

         17. This Guaranty is a Loan Document and,  therefore,  this Guaranty is
subject  to the  applicable  provisions  of the  Loan  Agreement,  all of  which
applicable  provisions are  incorporated  herein by reference the same as if set
forth herein  verbatim.  Moreover,  each Guarantor  acknowledges and agrees that
this Guaranty is subject to the offset provisions in favor of the Lenders in the
Loan Agreement.

         18. Each Guarantor  expressly  assumes all  responsibilities  to remain
informed of the financial condition of Borrower and any circumstances  affecting
(a)  Borrower's  ability to perform under the Loan  Agreement and the other Loan
Documents to which it is a party or (b) any collateral  securing all or any part
of the Guaranteed Indebtedness.

         19. In the event that any  Guarantor  is entitled to receive any notice
under the Uniform  Commercial Code, as it exists in the state governing any such
notice, of the sale or other  disposition of any collateral  securing all or any
part of the Guaranteed Indebtedness or this Guaranty, reasonable notice shall be
deemed given when such notice is deposited  in the United  States mail,  postage
prepaid,  at the address for Guarantor  set forth on the signature  page of this
Guaranty,  five  days  prior to the date any  public  sale,  or after  which any
private sale,  of any such  collateral is to be held;  provided,  however,  that
notice  given in any other  reasonable  manner or at any other  reasonable  time
shall be sufficient.

         20. No delay on the part of the Administrative  Agent in exercising any
right  hereunder  or failure to exercise  the same shall  operate as a waiver of
such right.  In no event shall any waiver of the  provisions of this Guaranty be
effective unless the same be in writing and signed by the appropriate parties in
accordance with the Loan Agreement,  and then only in the specific  instance and
for the purpose given.

     21.  Nothing  contained  herein shall be construed as an  obligation on the
part of the Agents or the  Lenders  to extend or  continue  to extend  credit to
Borrower.



<PAGE>


         22.  Notwithstanding  any other  provision  of this  Guaranty or of any
instrument or agreement evidencing, governing or securing all or any part of the
Guaranteed  Indebtedness,  each  Guarantor and the  Administrative  Agent by its
acceptance hereof agree that no Guarantor shall ever be required or obligated to
pay  interest  in  excess of the  maximum  nonusurious  interest  rate as may be
authorized by applicable  law for the written  contracts  which  constitute  the
Guaranteed Indebtedness.  It is the intention of Guarantors, the Agents, and the
Lenders to conform  strictly to the applicable  laws which limit interest rates,
and any of the aforesaid contracts for interest, if and to the extent payable by
Guarantors,  shall be held to be subject to reduction to the maximum nonusurious
interest rate allowed under said law.

         23. THIS GUARANTY IS EXECUTED AND DELIVERED AS AN INCIDENT TO A LENDING
TRANSACTION  CONSUMMATED AND PERFORMABLE IN TRAVIS COUNTY,  TEXAS,  AND SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

         24. Each Guarantor  shall pay on demand all reasonable  attorneys' fees
and all other  costs  and  expenses  incurred  by the  Agents  or any  Lender in
connection with the enforcement or collection of this Guaranty.

         25. THIS GUARANTY  EMBODIES THE FINAL,  ENTIRE AGREEMENT OF GUARANTORS,
THE  AGENTS  AND  THE  LENDERS  WITH  RESPECT  TO  GUARANTORS'  GUARANTY  OF THE
GUARANTEED INDEBTEDNESS AND RESTATES ANY AND ALL PRIOR COMMITMENTS,  AGREEMENTS,
REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER WRITTEN OR ORAL, RELATING TO THE
SUBJECT MATTER HEREOF.  THIS GUARANTY IS INTENDED BY GUARANTORS,  THE AGENTS AND
THE LENDERS AS A FINAL AND COMPLETE EXPRESSION OF THE TERMS OF THE GUARANTY, AND
NO COURSE OF DEALING BETWEEN ANY GUARANTOR, THE AGENTS OR THE LENDERS, NO COURSE
OF PERFORMANCE, NO TRADE PRACTICES, AND NO EVIDENCE OF PRIOR, CONTEMPORANEOUS OR
SUBSEQUENT  ORAL  AGREEMENTS OR DISCUSSIONS OR OTHER  EXTRINSIC  EVIDENCE OF ANY
NATURE SHALL BE USED TO CONTRADICT,  VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS
GUARANTY.  THERE ARE NO ORAL  AGREEMENTS  AMONG  GUARANTORS,  THE AGENTS AND THE
LENDERS.

                     [REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGES FOLLOW.]


<PAGE>








         EXECUTED as of the 31st day of January, 2000.

                                                     GUARANTORS:
                                                     ----------

                                         PROSTATHERAPIES, INC.,
                                         a Delaware corporation
                                         LITHOTRIPTORS, INC.,
                                         a North Carolina corporation
                                         FASTSTART, INC.,
                                         a North Carolina corporation
                                         NATIONAL LITHOTRIPTORS ASSOCIATION,
                                         a North Carolina corporation
                                         R.R. LITHO, INC.,
                                         a Delaware corporation
                                         OHIO LITHO, INC.,
                                         a Delaware corporation
                                         MEDTECH INVESTMENT, INC.,
                                         a North Carolina corporation
                                         PRIME MEDICAL OPERATING, INC.,
                                         a Delaware corporation
                                         PRIME MANAGEMENT, INC.,
                                         a Nevada corporation
                                         PRIME LITHOTRIPTER OPERATIONS, INC.,
                                         a New York corporation
                                         PRIME DIAGNOSTIC SERVICES, INC.,
                                         a Delaware corporation
                                         PRIME LITHOTRIPSY SERVICES, INC.,
                                         a New York corporation
                                         PRIME DIAGNOSTIC CORP. OF FLORIDA,
                                         a Delaware corporation
                                         SUN MEDICAL TECHNOLOGIES, INC.,
                                         a California corporation
                                         PRIME PRACTICE MANAGEMENT, INC.,
                                         a New York corporation
                                         PRIME CARDIAC REHABILITATION SERVICES,
                                         INC., a Delaware corporation
                                         ALABAMA RENAL STONE INSTITUTE, INC.,
                                         an Alabama corporation
                                         PRIME KIDNEY STONE TREATMENT, INC.,
                                         a New Jersey corporation
                                         SUN ACQUISITION, INC.,
                                         a California corporation
                                         EXECUTIVE MEDICAL ENTERPRISES, INC.,
                                         a Delaware corporation


<PAGE>








                        PRIME RVC, INC.,
                        a Delaware corporation

                           By: /s/ Teena E. Belcik
                                 Teena E. Belcik
                                 Treasurer

                         PRIME MEDICAL MANAGEMENT, L.P.,
                         a Delaware limited partnership

                           By:   Prime Medical Operating, Inc.,
                                 a Delaware corporation, its
                                 General Partner

                           By: /s/ Teena E. Belcik
                                 Teena E. Belcik
                                 Treasurer

                         PRIME REFRACTIVE, L.L.C.


                           By: /s/ Teena E. Belcik
                                 Teena E. Belcik
                                 Treasurer

                           Address for Notices:
                           1301 Capital of Texas Highway
                           Suite C-300
                           Austin, Texas 78746
                           Attn: President
                           Fax Number:  (512) 328-8510
                           Telephone Number:  (512) 328-2892


<PAGE>



                               GUARANTY AGREEMENT

         WHEREAS,  PRIME  REFRACTIVE  MANAGEMENT,  L.L.C.,  a  Delaware  limited
liability company  ("Borrower"),  has entered into a Loan Agreement of even date
herewith with certain banks and other lending institutions which are or may from
time to time become signatories  thereto,  BANKBOSTON,  N.A., a national banking
association,  as documentation  agent for itself and the other Lenders,  BANK OF
AMERICA,  N.A. ("B of A"), a national  banking  association,  as  administrative
agent for itself and the other  Lenders  (in such  capacity,  together  with its
successors in such capacity, the "Administrative Agent"),  pursuant to which the
Lenders have agreed to make an advancing term loan to the Borrower with advances
thereunder not to exceed an aggregate  principal  amount of Fourteen Million and
00/100  Dollars  ($14,000,000.00)  (such  Loan  Agreement,  as may  be  amended,
extended,  restated,  supplemented  or  modified  from  time to time,  the "Loan
Agreement");  terms  defined in the Loan  Agreement  and not  otherwise  defined
herein are used herein as defined therein; and

         WHEREAS,  the Agents and the Lenders have conditioned their obligations
under  the  Loan   Agreement  upon  the  execution  and  delivery  by  Guarantor
(hereinafter defined) of this Guaranty Agreement (this "Guaranty");

         NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which are hereby acknowledged, the undersigned ("Guarantor"), hereby irrevocably
and unconditionally  guarantees to the Agents, and to the Lenders,  the full and
prompt  payment and  performance  of the  Guaranteed  Indebtedness  (hereinafter
defined), this Guaranty being upon the following terms:

         1 . The term "Guaranteed Indebtedness", as used herein means all of the
Obligations  and shall include any and all  post-petition  interest and expenses
(including  attorneys'  fees)  whether  or not  allowed  under  any  bankruptcy,
insolvency, or other similar law.

         2. This Guaranty  shall be an absolute,  continuing,  irrevocable,  and
unconditional  guaranty  of  payment  and  performance,  and not a  guaranty  of
collection, and Guarantor shall remain liable on its obligations hereunder until
the  payment  and  performance  in  full  of  the  Guaranteed  Indebtedness  and
termination of the Commitments. No set-off, counterclaim, recoupment, reduction,
or  diminution  of any  obligation,  or any defense of any kind or nature  which
Borrower  may have against any Agent,  any Lender or any other  party,  or which
Guarantor may have against Borrower or any other party (other than the Agents or
any Lender),  shall be available to, or shall be asserted by, Guarantor  against
any Agent, any Lender or any subsequent holder of the Guaranteed Indebtedness or
any part thereof or against  payment of the Guaranteed  Indebtedness or any part
thereof.

         3.  Notwithstanding  any  contrary  provision,  it is the  intention of
Guarantor,  Lenders,  and Agents that the amount of the Guaranteed  Indebtedness
guaranteed  by  Guarantor by this  Guaranty  shall be, but not in excess of, the
maximum  amount  permitted by fraudulent  conveyance,  fraudulent  transfer,  or
similar Laws applicable to Guarantor.  Accordingly,  notwithstanding anything to
the contrary  contained in this  Guaranty or any other  agreement or  instrument
executed in connection  with the payment of any of the Guaranteed  Indebtedness,
the  amount of the  Guaranteed  Indebtedness  guaranteed  by  Guarantor  by this
Guaranty  shall be limited to an aggregate  amount  equal to the largest  amount
that would not render  Guarantor's  obligations  hereunder  subject to avoidance
under  Section  548 of the  United  States  Bankruptcy  Code  or any  comparable
provision of any applicable state law.


<PAGE>





                                       12



<PAGE>


         4. If Guarantor  becomes liable for any indebtedness  owing by Borrower
to any Agent or any Lender by  endorsement  or otherwise,  other than under this
Guaranty, such liability shall not be in any manner impaired or affected hereby,
and the rights of the Agents and the Lenders  hereunder  shall be  cumulative of
any and all other  rights that the Agents and the Lenders may ever have  against
Guarantor.  The  exercise  by the  Agents  or any  Lender of any right or remedy
hereunder  or under  any other  instrument,  or at law or in  equity,  shall not
preclude the concurrent or subsequent exercise of any other right or remedy.

         5. In the event of default by Borrower in payment or performance of the
Guaranteed Indebtedness,  or any part thereof, when such Guaranteed Indebtedness
becomes due,  whether by its terms,  by  acceleration,  or otherwise,  Guarantor
shall promptly pay the amount due thereon to the  Administrative  Agent, for the
benefit of the Lenders,  upon demand in lawful  currency of the United States of
America and it shall not be necessary for the Administrative  Agent, in order to
enforce  such  payment by  Guarantor,  first to  institute  suit or exhaust  its
remedies against Borrower or others liable on such Guaranteed  Indebtedness,  or
to enforce any rights against any collateral which shall ever have been given to
secure such Guaranteed Indebtedness.

         6. If  acceleration  of the time for  payment of any amount  payable by
Borrower  under  the  Guaranteed  Indebtedness  is stayed  upon the  insolvency,
bankruptcy, or reorganization of Borrower, all such amounts otherwise subject to
acceleration under the terms of the Guaranteed Indebtedness shall nonetheless be
payable by Guarantor hereunder forthwith on demand by the Administrative Agent.


<PAGE>


         7.  Guarantor  hereby agrees that its  obligations  under this Guaranty
shall not be released,  discharged,  diminished,  impaired, reduced, or affected
for any reason or by the occurrence of any event, including, without limitation,
one or more of the  following  events,  whether  or not  with  notice  to or the
consent of Guarantor:  (a) the taking or accepting of collateral as security for
any or all of the  Guaranteed  Indebtedness  or the  sale,  release,  surrender,
exchange,  or subordination  of any collateral now or hereafter  securing any or
all of the Guaranteed Indebtedness;  (b) any partial release of the liability of
Guarantor  hereunder,  or the full or partial  release of  Borrower or any other
guarantor from liability for any or all of the Guaranteed Indebtedness;  (c) the
dissolution,  insolvency,  or  bankruptcy of Borrower,  Guarantor,  or any other
party  at any  time  liable  for  the  payment  of any or all of the  Guaranteed
Indebtedness;  (d) any renewal, extension,  modification,  waiver, amendment, or
rearrangement  of any or all of the Guaranteed  Indebtedness  or any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed  Indebtedness;  (e) any adjustment,  indulgence,  forbearance,
waiver,  settlement,  or compromise that may be granted or given by any Agent or
any Lender to Borrower, Guarantor, or any other party ever liable for any or all
of the Guaranteed  Indebtedness;  (f) the subordination of the payment of all or
any part of the  Guaranteed  Indebtedness  to the  payment  of any  obligations,
indebtedness,  or  liabilities  which  may be due  or  become  due to any of the
Agents,  any of the  Lenders  or  others;  (g) the  application  of any  deposit
balance,  fund,  payment,  collections  through process of law or otherwise,  or
other  collateral  of  Borrower  to  the  satisfaction  and  liquidation  of the
indebtedness or obligations of Borrower to Agents or any of the Lenders, if any,
not guaranteed under this Guaranty;  (h) the application of any sums paid to any
of the Agents or any of the Lenders by Guarantor,  any other guarantor of all or
any part of the  Guaranteed  Indebtedness,  Borrower or others to the Guaranteed
Indebtedness  in such order and manner as any Agent may  determine in accordance
with the Loan Agreement;  (i) any neglect, delay, omission,  failure, or refusal
of any Agent or any Lender to take or prosecute any action for the collection of
any of the  Guaranteed  Indebtedness  or to foreclose  or take or prosecute  any
action in connection with any  instrument,  document,  or agreement  evidencing,
securing,  or otherwise  relating to any or all of the Guaranteed  Indebtedness;
(j)  the  unenforceability  or  invalidity  of any  or  all  of  the  Guaranteed
Indebtedness or of any instrument,  document, or agreement evidencing, securing,
or  otherwise  relating to any or all of the  Guaranteed  Indebtedness;  (k) any
payment  by  Borrower  or any other  party to any Agent or any Lender is held to
constitute a preference under applicable  bankruptcy or insolvency law or if for
any other  reason any Agent or any Lender is  required  to refund any payment or
pay the amount  thereof to someone else; (l) the settlement or compromise of any
of the Guaranteed Indebtedness;  (m) the non-perfection of any security interest
or lien securing any or all of the Guaranteed  Indebtedness;  (n) any impairment
of any collateral  securing any or all of the Guaranteed  Indebtedness;  (o) the
failure of any Agent or any Lender to sell any collateral securing any or all of
the Guaranteed  Indebtedness in a commercially reasonable manner or as otherwise
required  by law;  (p) any  change in the  corporate  existence,  structure,  or
ownership  of  Borrower;  (q)  any  other  circumstance  which  might  otherwise
constitute  a  defense  available  to,  or  discharge  of,  Borrower;   (r)  the
unenforceability  of all or any  part  of the  Guaranteed  Indebtedness  against
Borrower  by reason of the fact that the  Guaranteed  Indebtedness  exceeds  the
amount  permitted  by  law;  (s)  the  act of  creating  all or any  part of the
Guaranteed  Indebtedness is ultra vires; or (t) the officers creating all or any
part of the Guaranteed Indebtedness acted in excess of their authority.

     8.   Guarantor hereby represents and warrants to the Agents and the Lenders
          the  following:

               (a) This Guaranty may reasonably be expected to benefit, directly
          or indirectly, Guarantor.

                  (b) Guarantor is familiar with, and has independently reviewed
         the books and records  regarding,  the financial  condition of Borrower
         and is familiar with the value of any and all collateral intended to be
         security  for  the  payment  of  all  or any  part  of  the  Guaranteed
         Indebtedness.  However,  Guarantor  is not  relying  on such  financial
         condition or collateral as an inducement to enter into this Guaranty.

                  (c) Guarantor has adequate  means to obtain from Borrower on a
         continuing  basis  information  concerning  the financial  condition of
         Borrower,  and Guarantor is not relying on the Agents or the Lenders to
         provide such information to Guarantor either now or in the future.

                  (d) Guarantor has the power and authority to execute, deliver,
         and perform  this  Guaranty and any other  agreements  executed by such
         Guarantor contemporaneously herewith, and the execution,  delivery, and
         performance  of this  Guaranty  and any other  agreements  executed  by
         Guarantor  contemporaneously  herewith  do not and will not violate (i)
         any agreement or instrument to which  Guarantor is a party, or (ii) any
         law, rule, regulation,  or order of any Governmental Authority to which
         Guarantor is subject.

                  (e) Neither the Agents,  the Lenders,  nor any other party has
         made any representation,  warranty,  or statement to Guarantor in order
         to induce any Guarantor to execute this Guaranty.

                  (f) The financial  statements and other financial  information
         regarding Guarantor  heretofore and hereafter delivered to any Agent or
         any Lender are and shall be true and correct in all  material  respects
         and fairly present the financial  position of Guarantor as of the dates
         thereof,  and no material  adverse change has occurred in the financial
         condition of Guarantor as reflected in those financial disclosures.

                  (g) As of the date  hereof,  and after  giving  effect to this
         Guaranty and the  obligations  evidenced  hereby,  (i) Guarantor is and
         will be Solvent  (to the extent  necessary,  taking  into  account  any
         rights of contribution,  reimbursement and subrogation),  (ii) the fair
         saleable  value of  Guarantor's  assets  exceeds  and will  continue to
         exceed its liabilities (both fixed and contingent),  (iii) Guarantor is
         and will continue to be able to pay its debts as they mature,  and (iv)
         Guarantor has and will continue to have sufficient  capital to carry on
         its business and all businesses in which it is about to engage.

               (h) All  representations  and warranties  about Guarantor made in
          the Loan Agreement are true and correct.


<PAGE>


         9.  Guarantor  hereby  represents  and  warrants  to the Agents and the
Lenders  that (for  purposes  of  Sections 9 and 10, all  capitalized  terms not
otherwise defined shall have the meanings assigned thereto in the Fourth Amended
and Restated Loan Agreement dated the date hereof (the "Prime  Agreement") among
Guarantor, B of A, as administrative agent,  BankBoston,  N.A., as documentation
agent,  and the lenders from time to time defined  therein;  provided,  that the
terms  "Loan  Documents",  "Obligations",   "Agents",  "Lenders",  "Guarantors",
"Administrative       Agent",       "Agent",       "Collateral",       "Guaranty
Agreement","Commitment",  shall have the  meaning  assigned  thereto in the Loan
Agreement):

         9.1      Existence.

         (a) Corporate Existence. Each of the Companies (other than the Excepted
Subsidiaries and the Partnerships): (a) is a corporation duly organized, validly
existing,  and in  good  standing  under  the  laws of the  jurisdiction  of its
incorporation;  (b) has all requisite  corporate  power and authority to own its
assets and carry on its  business as now being or as  proposed to be  conducted;
and (c) is qualified to do business in all  jurisdictions in which the nature of
its business makes such qualification  necessary and where failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Guarantor,  or any Material  Subsidiary.  Each Company  (other than the Excepted
Subsidiaries)  has the corporate  power and authority to execute,  deliver,  and
perform  its  obligations  under  this  Guaranty  Agreement  and the other  Loan
Documents to which it is or may become a party.

         (b) Partnership Existence.  Each of the Partnerships:  (a) is a general
partnership,  limited  partnership or limited liability company, as appropriate,
duly  organized,  validly  existing,  and in good standing under the laws of the
jurisdiction  of its  formation;  (b) has all  requisite  partnership  power and
authority or company power and authority, as appropriate,  to own its assets and
carry on its  business as now being or as proposed to be  conducted;  and (c) is
qualified  to do  business  in all  jurisdictions  in which  the  nature  of its
business  makes such  qualification  necessary  and where  failure to so qualify
would have a material  adverse effect on the business,  condition  (financial or
otherwise),  operations,  or  properties  of the  Companies  taken  as a  whole,
Guarantor, or any Material Subsidiary.

         9.2 Financial Statements. Guarantor has delivered to the Administrative
Agent audited  consolidated  financial statements of the Companies as of and for
the fiscal year ended  December 31, 1998, and unaudited  consolidated  financial
statements of Guarantor for the nine (9) month period ended  September 30, 1999.
Such financial statements have been prepared in accordance with GAAP, and fairly
present,  on a consolidated  basis, the financial condition of the Companies and
Litho and the Partnerships, as appropriate, as of the respective dates indicated
therein and the  results of  operations  for the  respective  periods  indicated
therein.  There has been no material  adverse change in the business,  condition
(financial or otherwise),  operations, or properties of the Companies taken as a
whole,  Guarantor,  or any Material  Subsidiary  since the effective date of the
most recent financial statements referred to in this Section.

     9.3 Corporate Action: No Breach. The execution,  delivery,  and performance
by each  Company of the Loan  Documents to which such Company is or may become a
party and compliance with the terms and provisions  hereof and thereof have been
duly  authorized  by all  requisite  corporate  action (or, if such Company is a
partnership, then partnership action) on the part of such Company and do not and
will not (a) violate or conflict  with, or result in a breach of, or require any
consent under (i) the articles of  incorporation  or bylaws of such Company (or,
if such  Company  is a  partnership,  then  the  partnership  agreement  of such
Company),  (ii) any material applicable law, rule, or regulation or any material
order, writ, injunction,  or decree of any Governmental Authority or arbitrator,
or (iii) any material  agreement or  instrument to which such Company is a party
or by which such Company or any of its property is bound or subject  (other than
agreements  and  instruments  relating  to Debt  which will be paid off with the
proceeds of the initial Advance), or (b) constitute a material default under any
such agreement or instrument (other than agreements and instruments  relating to
Debt which will be paid off with the proceeds of the initial Advance), or result
in the  creation or  imposition  of any Lien (except as provided in Article V of
the Prime Agreement) upon any of the revenues or assets of any of the Companies.



<PAGE>


         9.4  Operation  of  Business.  Each of the  Companies  (other  than the
Excepted Subsidiaries)  possesses all licenses,  permits,  franchises,  patents,
copyrights,  trademarks, and tradenames, or rights thereto, necessary to conduct
their  respective  businesses  substantially  as now  conducted and as presently
proposed to be  conducted.  None of the  Companies  is in violation of any valid
rights of others with respect to any of the foregoing  (except where the failure
to do so would not have a material  adverse  effect on the  business,  condition
(financial or otherwise),  operations or properties of the Companies  taken as a
whole, Guarantor, or any Material Subsidiary).

         9.5  Litigation  and  Judgments.  As of  the  date  hereof,  except  as
disclosed  on Schedule  7.5 to the Prime  Agreement,  there is no action,  suit,
investigation,  or  proceeding  before  or  by  any  Governmental  Authority  or
arbitrator  pending,  or to the  knowledge of Guarantor,  threatened  against or
affecting any of the  Companies,  that would,  if adversely  determined,  have a
material  adverse  effect on the business,  condition  (financial or otherwise),
operations or properties of the Companies  taken as a whole,  Guarantor,  or any
Material  Subsidiary  or the  ability  of  Guarantor  to  pay  and  perform  the
Obligations. There are no outstanding judgments against any Company.

         9.6 Rights in  Properties;  Liens.  Each of the  Companies has good and
indefeasible title to or valid leasehold  interests in their respective material
properties and assets, real and personal, including the properties,  assets, and
leasehold interests reflected in the financial  statements  described in Section
9.2, and none of the properties,  assets, or leasehold  interests of any Company
is  subject  to any  Lien,  except  as  permitted  by  Section  9.2 of the Prime
Agreement.

         9.7 Enforceability.  This Guaranty Agreement constitutes, and the other
Loan Documents to which Guarantor is a party,  when delivered,  shall constitute
the legal,  valid,  and binding  obligations  of Borrower,  enforceable  against
Guarantor  in  accordance  with  their  respective  terms,  except as limited by
bankruptcy,  insolvency,  or other laws of general  application  relating to the
enforcement of creditors' rights. The Loan Documents to which each other Company
is a party,  when  delivered,  shall  constitute the legal,  valid,  and binding
obligations of such Company, enforceable against such Company in accordance with
their respective terms,  except as limited by bankruptcy,  insolvency,  or other
laws of general application relating to the enforcement of creditors' rights.

         9.8 Approvals. No authorization, approval, or consent of, and no filing
or registration  with, any  Governmental  Authority or third party is or will be
necessary  for the  execution,  delivery,  or  performance  by  Guarantor or any
Company  of this  Guaranty  Agreement  and the  other  Loan  Documents  to which
Guarantor  or any  Company  is or may  become  a party  or for the  validity  or
enforceability thereof.

     9.9 Debt.  As of the date hereof,  the  Companies  have no Debt,  except as
disclosed on Schedule 7.9 to the Prime Agreement.

         9.10 Taxes. The Companies (other than the Excepted  Subsidiaries)  have
filed or extended all tax returns  (federal,  state,  and local)  required to be
filed,  including all income,  franchise,  employment,  property,  and sales tax
returns,  and  have  paid  all  of  their  respective   liabilities  for  taxes,
assessments,  governmental  charges,  and other  levies that are due and payable
other than certain state tax returns  required to be filed on or before the date
hereof.  Except as previously  disclosed to the Administrative Agent in writing,
no  Company  knows of any  pending  investigation  of any of them by any  taxing
authority or of any pending but unassessed tax liability of any of them,  except
relating to the Excepted Subsidiaries.


<PAGE>


         9.11  Use  of  Proceeds;  Margin  Securities.  No  Company  is  engaged
principally, or as one of its important activities, in the business of extending
credit for the  purpose of  purchasing  or  carrying  margin  stock  (within the
meaning  of  Regulations  T, U, or X of the Board of  Governors  of the  Federal
Reserve  System),  and no part of the  proceeds of any  Advance  will be used to
purchase or carry any margin stock or to extend credit to others for the purpose
of purchasing  or carrying  margin  stock,  except for purchases of  Guarantor's
capital stock permitted by Section 9.4 of the Prime Agreement.

         9.12 ERISA.  The Companies  are in compliance in all material  respects
with all  applicable  provisions  of  ERISA.  Neither a  Reportable  Event nor a
Prohibited  Transaction has occurred and is continuing with respect to any Plan.
No notice of intent to  terminate a Plan has been  filed,  nor has any Plan been
terminated.  No circumstances  exist which constitute grounds entitling the PBGC
to institute  proceedings to terminate,  or appoint a trustee to  administer,  a
Plan, nor has the PBGC  instituted any such  proceedings.  None of the Companies
nor  any  ERISA   Affiliate  has  completely  or  partially   withdrawn  from  a
Multi-employer  Plan.  The  Companies  and each ERISA  Affiliate  have met their
minimum funding requirements under ERISA with respect to all of their Plans, and
the  present  value of all vested  benefits  under each Plan does not exceed the
fair market value of all Plan assets  allocable to such benefits,  as determined
on the most recent  valuation,  date of the Plan and in  accordance  with ERISA.
None of the Companies nor any ERISA  Affiliate has incurred any liability to the
PBGC under ERISA.

         9.13 Disclosure.  All factual  information (taken as a whole) furnished
by or on behalf of Guarantor  in writing to any Agent or any Lender  (including,
without limitation, all factual information contained in the Loan Documents) for
purposes  of or in  connection  with this  Guaranty  Agreement,  the other  Loan
Documents or any  transaction  contemplated  herein or therein is, and all other
such factual  information (taken as a whole) hereafter furnished by or on behalf
of Guarantor  in writing will be, true and accurate in all material  respects on
the date as of which such factual  information  is dated or certified and is not
(and such factual  information  (taken as a whole) hereafter  furnished will not
be)  incomplete  by omitting to state any facts  necessary  to make such factual
information  (taken as a whole) not  misleading in any material  respect at such
time in light of the  circumstances  under which such  factual  information  was
provided.

         9.14 Subsidiaries;  Partnerships. Each of the Guarantors is a direct or
indirect  wholly-owned  Subsidiary  of  Guarantor,  and as of the  date  hereof,
together  with the  Partnerships  listed on  Schedule 3 to the Prime  Agreement,
constitute all of the  Subsidiaries  of Guarantor.  Schedule 7.14.1 to the Prime
Agreement,  as the same may be amended from time to time to reflect transactions
permitted by this Agreement,  sets forth the outstanding shares of capital stock
(or other ownership  interests) and the name of each  shareholder of each of the
Subsidiaries of Guarantor. All of the outstanding capital stock of Guarantor and
each of its  Subsidiaries  has  been  validly  issued,  is  fully  paid,  and is
nonassessable.  Schedule  7.14.2  to the  Prime  Agreement,  as the  same may be
amended from time to time to reflect  transactions  permitted  by this  Guaranty
Agreement,  sets forth the outstanding partnership interests of the Partnerships
owned by each of the Companies.

         9.15  Agreements.  Except for the Senior  Subordinated  Indenture,  the
Senior  Subordinated  Notes,  and as set  forth on  Schedule  7.15 to the  Prime
Agreement,  none of the Companies is a party to any  indenture,  loan, or credit
agreement,  or to any lease or other agreement or instrument,  or subject to any
charter or corporate  restriction  which could  reasonably be expected to have a
material  adverse  effect on the business,  condition  (financial or otherwise),
operations or properties of the Companies  taken as a whole,  Guarantor,  or any
Material  Subsidiary  or the ability of  Guarantor  or any  Guarantor to pay and
perform its obligations under the Loan Documents to which it is a party. None of
the  Companies  is in  default  in any  material  respect  in  the  performance,
observance,  or fulfillment of any of the obligations,  covenants, or conditions
contained in any agreement or instrument to which it is a party,  which default,
in the aggregate  with all such other  defaults,  would have a material  adverse
affect on the  business,  condition  (financial  or  otherwise),  operations  or
properties  of the  Companies  taken  as a  whole,  Guarantor,  or any  Material
Subsidiary.

         9.16  Compliance with Legal Requirements; Governmental Authorizations.



<PAGE>


         (a) Except for the Excepted  Subsidiaries  and as set forth in Schedule
7.16.1 to the Prime Agreement: (i) each Company is in compliance in all material
respects with each Legal  Requirement  that is or was applicable to it or to the
conduct or  operation  of its  business  or the  ownership  or use of any of its
assets; and (ii) no Company has received any notice or other  communication from
any  Governmental  Authority or other Person of any event or circumstance  which
could  constitute  a  violation  of,  or  failure  to  comply  with,  any  Legal
Requirement.

         (b) Except for the Excepted  Subsidiaries  and as set forth in Schedule
7.16 to the Prime Agreement: (i) each Company is in material compliance with all
of the terms and requirements of each  Governmental  Authorization  held by such
Company; (ii) no Company has received any notice or other communication from any
Governmental Authority or other Person of, any event or circumstance which could
constitute a violation of, or failure to comply with, any term or requirement of
any  Governmental  Authorization,  or of any  actual  or  potential  revocation,
withdrawal,  cancellation  or termination of, or material  modification  to, any
Governmental  Authorization;  (iii) all applications required to have been filed
for the renewal of any required Governmental Authorizations have been duly filed
on a timely basis with the appropriate Governmental  Authorities,  and all other
filings   required  to  have  been  made  with  respect  to  such   Governmental
Authorizations  have  been  duly  made on a timely  basis  with the  appropriate
Governmental Authorities;  (iv) all Governmental Authorizations of the Companies
are  transferable to the Companies;  (v) upon  consummation of the  transactions
contemplated  hereby,  the Companies  will  lawfully hold all such  Governmental
Authorizations; and (vi) none of such Governmental Authorizations will terminate
upon  consummation  of the  transactions  contemplated  hereby.  Except  for the
Excepted  Subsidiaries and as set forth on Schedule 7.16 to the Prime Agreement,
each of the Companies  possesses the necessary  Governmental  Authorizations (i)
necessary to permit each Company to lawfully  conduct and operate its respective
business in the manner it currently  conducts and operates  such business and to
permit  such  Company  to own and use its  assets  in the  manner  in  which  it
currently owns and uses such assets,  and (ii) necessary to permit each Company,
upon the  consummation  of the  transactions  contemplated  hereby,  to lawfully
conduct and operate its  business  and to permit each Company to own and use its
assets,  where the failure to have such Governmental  Authorization would have a
material  adverse  effect on the business,  condition  (financial or otherwise),
operations or properties of the Companies  taken as a whole,  Guarantor,  or any
Material Subsidiary.

     9.17 Investment  Company Act. No Company is an "investment  company" within
the meaning of the Investment Company Act of 1940, as amended.

         9.18  Public  Utility  Holding  Company  Act.  No Company is a "holding
company" or a "subsidiary company" of a "holding company" or an "affiliate" of a
"holding company" or a "public utility" within the meaning of the Public Utility
Holding Company Act of 1935, as amended.

     9.19  Environmental  Matters.  Except as disclosed on Schedule  7.19 to the
Prime Agreement, as the same may be amended from time to time, hereto:

         (a)  Each of the  Companies  and all of  their  respective  properties,
assets,  and  operations  are in  compliance  in all material  respects with all
Environmental Laws. No Company is aware of, nor have any of them received notice
of, any past, present, or future conditions,  events, activities,  practices, or
incidents  which may  interfere  with or  prevent  the  material  compliance  or
continued  material  compliance  of any Company with all material  Environmental
Laws; and

         (b) The  Companies  have  obtained all material  permits,  licenses and
authorizations  that are required under applicable  Environmental  Laws, and all
such  permits are in good  standing  and each  Company is in  compliance  is all
material respects with all of the terms and conditions of such permits.


<PAGE>


         9.20 Year 2000 Compliance. Guarantor represents that it is aware of the
possible  impact  of the year 2000  problem  (that  is,  the risk that  computer
applications may not be able to properly perform date-sensitive  functions after
December  31,  1999)  upon its  computer  applications  and  on-going  business.
Borrower  represents that any corrective action necessary will be taken and that
the year 2000  problem  will not  result  in a  material  adverse  change in the
Companies' business condition (financial or otherwise),  operations,  properties
or prospects, or ability to repay the Obligations.

         10.  Guarantor  agrees to deliver to  Administrative  Agent each of the
items described in Section 8.1 of the Prime Agreement on the same dates required
by the Prime Agreement. In addition,  Guarantor will perform and observe each of
the following  positive covenants so long as the Obligations or any part thereof
are outstanding or any Lender has any Commitment under the Loan Agreement:

         10.1  Maintenance  of Existence;  Conduct of Business.  Guarantor  will
preserve and maintain its corporate existence and all of its leases, privileges,
licenses, permits, franchises,  qualifications, and rights that are necessary or
desirable in the ordinary conduct of its business.  Guarantor will cause each of
its Subsidiaries other than the Excepted Subsidiaries,  to preserve and maintain
its  corporate,  partnership  or other similar  existence and all of its leases,
privileges,  licenses, permits,  franchises,  qualifications and rights that are
necessary or desirable in the ordinary conduct of its business,  except, in each
case,  where  failure to do so would not have a material  adverse  effect on the
business,  condition  (financial or otherwise),  operations or properties of the
Companies taken as a whole,  Guarantor,  or any Material  Subsidiary.  Guarantor
will conduct,  and will cause each of its Subsidiaries to conduct,  its business
in an orderly and efficient manner in accordance with good business practices.

         10.2  Maintenance  of Properties.  Guarantor  will maintain,  keep, and
preserve,  and cause each of its  Subsidiaries to maintain,  keep, and preserve,
all of its  properties  (tangible  and  intangible)  necessary  or useful in the
proper conduct of its business in good working order and condition,  except,  in
each case,  as  permitted  by Section 9.8 of the Prime  Agreement  or 9.9 of the
Prime Agreement or where the failure to do so would not have a material  adverse
effect on the  business,  condition  (financial  or  otherwise),  operations  or
properties  of the  Companies  taken  as a  whole,  Guarantor,  or any  Material
Subsidiary.

         10.3 Taxes and Claims.  Guarantor will pay or discharge, and will cause
each  of its  Subsidiaries  other  than  the  Excepted  Subsidiaries,  to pay or
discharge,  at or before maturity or before becoming delinquent (a) all material
taxes, levies, assessments, and governmental charges imposed on it or its income
or profits or any of its material  property,  and (b) all material lawful claims
for labor,  material,  and supplies,  which, if unpaid, might become a Lien upon
any of its property; provided, however, that no Company shall be required to pay
or discharge any tax, levy,  assessment,  or governmental  charge which is being
contested in good faith by appropriate  proceedings  diligently pursued, and for
which adequate reserves have been established.

         10.4  Insurance.  Guarantor will  maintain,  and will cause each of its
Subsidiaries to maintain (except in the case of the Partnerships,  in which case
Guarantor shall maintain for the Partnerships), insurance with financially sound
and reputable  insurance companies in such amounts and covering such risks as is
usually carried by corporations engaged in similar businesses and owning similar
properties in the same general areas in which the Companies operate,  consistent
with past practices of the Companies and to the extent available on commercially
reasonable  terms,  provided that in any event Guarantor will maintain and cause
each of its Subsidiaries (except in the case of the Partnerships,  in which case
Guarantor   shall  maintain  for  the   Partnerships)   to  maintain   workmen's
compensation  insurance,  property  insurance,  comprehensive  general liability
insurance, professional liability insurance, and business interruption insurance
reasonably   satisfactory  to  the  Lenders.   Each  insurance  policy  covering
Collateral shall name the Administrative Agent as loss payee, for the benefit of
the Lenders, as its interests may appear and shall provide that such policy will
not be canceled or reduced without thirty (30) days' prior written notice to the
Administrative  Agent.  Guarantor will annually provide the Administrative Agent
with all  certificates  of  insurance  evidencing  all  policies of insurance of
Guarantor and its Subsidiaries.


<PAGE>


         10.5  Inspection  Rights.  At any reasonable time and from time to time
after reasonable notice to Guarantor, Guarantor will permit, and will cause each
of its Subsidiaries to permit,  representatives of the Administrative  Agent and
each Lender to examine,  copy, and make extracts from its books and records,  to
visit and inspect its properties,  and to discuss its business,  operations, and
financial  condition  with  its  officers,   and  independent  certified  public
accountants.  Prior to removing  any such  copies or  extracts  from a Company's
premises,  such  Company's   representatives  shall  be  provided  a  reasonable
opportunity to review such information and mark or identify it as "confidential"
or "confidential information" as reasonably deemed appropriate by such Company.

         10.6 Keeping Books and Records. Guarantor will maintain, and will cause
each of its  Subsidiaries  to  maintain,  proper  books of record and account in
which full,  true, and correct  entries in conformity with GAAP shall be made of
all dealings and transactions in relation to its business and activities.

         10.7 Compliance with Laws.  Guarantor will comply,  and will cause each
of its  Subsidiaries  to comply,  in all  material  respects  with all  material
applicable laws,  rules,  regulations,  orders,  and decrees of any Governmental
Authority or arbitrator.

         10.8 Compliance with Agreements.  Guarantor will comply, and will cause
each  of  its  Subsidiaries  to  comply,  in  all  material  respects  with  all
agreements, contracts, and instruments binding on it or affecting its properties
or business, except where the failure to do so would not have a material adverse
effect on the  business,  condition  (financial  or  otherwise),  operations  or
properties  of the  Companies  taken  as a  whole,  Guarantor,  or any  Material
Subsidiary.

         10.9 Further Assurances. Guarantor will (a), and will cause each of its
Subsidiaries  (other than the Partnerships) to, execute and deliver such further
agreements  and  instruments  and take such further  action as may be reasonably
requested by the  Administrative  Agent to carry out the provisions and purposes
of this Guaranty  Agreement and the other Loan Documents and, (b) and will cause
each of its Subsidiaries (including the Partnerships) to, create,  preserve, and
perfect the Liens of the  Administrative  Agent, for the benefit of the Lenders,
in the Collateral.

         10.10  ERISA.  Guarantor  will  comply,  and  will  cause  each  of its
Subsidiaries  to comply,  with all minimum funding  requirements,  and all other
material  requirements,  of ERISA, if applicable,  so as not to give rise to any
liability thereunder.

         10.11 Information Relating to Proposed Acquisitions. Guarantor will use
its best efforts to keep the  Administrative  Agent and the Lenders  informed of
the relevant  information  and status of and will share with the  Administrative
Agent and the Lenders and provide copies to the extent possible, of all material
due  diligence   information  relating  to  any  proposed  Permitted  Refractive
Acquisition  with  respect to which  Guarantor or any  Subsidiary  enters into a
letter of intent or  acquisition  agreement,  during  the term of this  Guaranty
Agreement.

     11.  Guarantor  covenants  and  agrees  that,  as  long  as the  Guaranteed
Indebtedness or any part thereof is outstanding or any Lender has any Commitment
under the Loan Agreement:

                  (a) No Guarantor shall, so long as its obligations  under this
         Guaranty  continue,  transfer  or pledge  any  material  portion of its
         assets for less than full and adequate consideration.

                  (b)   Each   Guarantor   shall   promptly   furnish   to   the
         Administrative  Agent at any time and from time to time such  financial
         statements and other financial  information as the Administrative Agent
         may require,  in form and substance  satisfactory to the Administrative
         Agent.


<PAGE>


                  (c) Each Guarantor  shall comply with all terms and provisions
         of the Loan Documents that apply to such Guarantor.

                  (d) Each Guarantor  shall promptly  inform the  Administrative
         Agent of (i) any litigation or governmental  investigation against such
         Guarantor  or  affecting  any  security  for  all  or any  part  of the
         Guaranteed   Indebtedness   or  this  Guaranty   which,  if  determined
         adversely,  might have a material  adverse  effect  upon the  financial
         condition  of such  Guarantor  or upon such  security  or might cause a
         default under any of the Loan Documents,  (ii) any claim or controversy
         which  might  become the  subject of such  litigation  or  governmental
         investigation,  and (iii) any material  adverse change in the financial
         condition of Guarantor.

         12. (a)  Guarantor  hereby  agrees that the  Subordinated  Indebtedness
(hereinafter defined) shall be subordinate and junior in right of payment to the
prior  payment in full of all  Guaranteed  Indebtedness,  and  Guarantor  hereby
assigns the  Subordinated  Indebtedness  to the  Administrative  Agent,  for the
benefit of the Lenders, as security for the Guaranteed Indebtedness. If any sums
shall be paid to  Guarantor by Borrower or any other person or entity on account
of the Subordinated Indebtedness,  such sums shall be held in trust by Guarantor
for the benefit of the  Administrative  Agent and shall forthwith be paid to the
Administrative  Agent without  affecting  the liability of Guarantor  under this
Guaranty and may be applied by the Administrative  Agent and the Lenders against
the Guaranteed Indebtedness in such order and manner as the Administrative Agent
and the Lenders may determine in their sole discretion.  Upon the request of the
Administrative  Agent,  Guarantor  shall  execute,  deliver,  and endorse to the
Administrative  Agent such documents and instruments as the Administrative Agent
may request to perfect, preserve, and enforce its rights hereunder. For purposes
of this Guaranty,  the term "Subordinated  Indebtedness" means all indebtedness,
liabilities,   and   obligations   of  Borrower  to   Guarantor,   whether  such
indebtedness,  liabilities,  and obligations now exist or are hereafter incurred
or arise, or whether the obligations of Guarantor thereon are direct,  indirect,
contingent,  primary,  secondary,  several, joint and several, or otherwise, and
irrespective  of whether such  indebtedness,  liabilities,  or  obligations  are
evidenced by a note, contract,  open account, or otherwise,  and irrespective of
the  person  or  persons  in whose  favor  such  indebtedness,  obligations,  or
liabilities may, at their inception,  have been, or may hereafter be created, or
the manner in which they have been or may hereafter be acquired by Guarantor.

                  (b)  Guarantor  agrees  that  any  and  all  liens,   security
interests, judgment liens, charges, or other encumbrances upon Borrower's assets
securing payment of any Subordinated  Indebtedness  shall be and remain inferior
and  subordinate  to any and all  liens,  security  interests,  judgment  liens,
charges,  or other  encumbrances  upon Borrower's assets securing payment of the
Guaranteed  Indebtedness  or  any  part  thereof,  regardless  of  whether  such
encumbrances in favor of Guarantor or the  Administrative  Agent presently exist
or are hereafter  created or attached.  Without the prior written consent of the
Lenders,  Guarantor  shall not (i) file suit  against  Guarantor  or exercise or
enforce  any  other  creditor's  right it may have  against  Guarantor,  or (ii)
foreclose, repossess, sequester, or otherwise take steps or institute any action
or  proceedings   judicial  or  otherwise,   including  without  limitation  the
commencement  of, or joinder  in, any  liquidation,  bankruptcy,  rearrangement,
debtor's  relief or  insolvency  proceeding)  to  enforce  any  liens,  security
interests,  collateral rights, judgments or other encumbrances held by Guarantor
on assets of Borrower.

                  (c)   In  the   event   of   any   receivership,   bankruptcy,
reorganization,  rearrangement,  debtor's relief, or other insolvency proceeding
involving Guarantor as debtor, the Administrative  Agent shall have the right to
prove and vote any claim  under the  Subordinated  Indebtedness  and to  receive
directly from the  receiver,  trustee or other court  custodian  all  dividends,
distributions,  and payments made in respect of the  Subordinated  Indebtedness.
The  Administrative  Agent  and  the  Lenders  may  apply  any  such  dividends,
distributions,  and payments  against the Guaranteed  Indebtedness in such order
and manner as the  Administrative  Agent and the Lenders may  determine in their
sole discretion.


<PAGE>


                  (d)  Guarantor  agrees  that all  promissory  notes,  accounts
receivable, ledgers, records, or any other evidence of Subordinated Indebtedness
shall contain a specific written notice thereon that the indebtedness  evidenced
thereby is subordinated under the terms of this Guaranty.

         13.  Guarantor  waives  (a)  promptness,   diligence,   and  notice  of
acceptance  of this  Guaranty  and notice of the  incurring  of any  obligation,
indebtedness,  or  liability  to which  this  Guaranty  applies or may apply and
waives presentment for payment, notice of nonpayment, protest, demand, notice of
protest,  notice of  intent to  accelerate,  notice of  acceleration,  notice of
dishonor,  diligence in enforcement,  and indulgences of every kind, and (b) the
taking  of any other  action  by the  Administrative  Agent,  including  without
limitation,  giving any notice of default or any other  notice to, or making any
demand on,  Guarantor,  any other guarantor of all or any part of the Guaranteed
Indebtedness  or any other party.  To the maximum extent lawful,  each Guarantor
waives all rights by which it might be  entitled  to require  suit on an accrued
right of action in  respect  of any  Guaranteed  Indebtedness  or  require  suit
against  Guarantor  or  others,  whether  arising  under ss.  34.02 of the Texas
Business  and  Commerce  Code,  as  amended  (regarding  its  right  to  require
Administrative  Agent or Lenders  to sue  Guarantor  on accrued  right of action
following its written notice to Administrative Agent or Lenders),  ss. 17.001 of
the Texas Civil Practice and Remedies Code, as amended (allowing suit against it
without suit against  Guarantor,  but  precluding  entry of judgment  against it
before entry of judgment against Guarantor), Rule 31 of the Texas Rules of Civil
Procedure,  as  amended  (requiring  Administrative  Agent  or  Lenders  to join
Guarantor in any suit against it unless  judgment  has been  previously  entered
against Guarantor), or otherwise.

         14. In addition  to any other  waivers,  agreements  and  covenants  of
Guarantor set forth herein,  Guarantor  hereby  further  waives and releases all
claims,  causes of action,  defenses  and offsets for any act or omission of the
Administrative  Agent, its directors,  officers,  employees,  representatives or
agents in  connection  with the  Administrative  Agent's  administration  of the
Guaranteed   Indebtedness,   except  for  the  Administrative   Agent's  willful
misconduct and gross negligence.

         15. This Guaranty shall  continue to be effective or be reinstated,  as
the case may be, if at any time any payment of all or any part of the Guaranteed
Indebtedness  is  rescinded  or must  otherwise  be returned by any Agent or any
Lender  upon  the  insolvency,   bankruptcy,  or  reorganization  of  Guarantor,
Guarantor,   any  other   guarantor  of  all  or  any  part  of  the  Guaranteed
Indebtedness, or otherwise, all as though such payment had not been made.

         16. Any acknowledgment or new promise,  whether by payment of principal
or  interest  or  otherwise  and  whether  by  Guarantor  or  others  (including
Guarantor),  with respect to any of the Guaranteed  Indebtedness  shall,  if the
statute of limitations in favor of Guarantor against the Administrative Agent or
any Lender  shall have  commenced  to run,  toll the running of such  statute of
limitations  and,  if the  period of such  statute  of  limitations  shall  have
expired, prevent the operation of such statute of limitations.

         17. This  Guaranty is for the benefit of the Agents and the Lenders and
their  respective  successors and assigns,  and in the event of an assignment of
the  Guaranteed  Indebtedness,  or any part  thereof,  the rights  and  benefits
hereunder,  to the extent  applicable to the  indebtedness  so assigned,  may be
transferred  with  such  indebtedness.  This  Guaranty  is  binding  not only on
Guarantor, but on Guarantor's successors and assigns.

         18.  Guarantor  recognizes  that the Agents and the Lenders are relying
upon  this  Guaranty  and the  undertakings  of  Guarantor  hereunder  in making
extensions  of  credit  to  Guarantor  under  the  Loan  Agreement  and  further
recognizes  that the  execution  and  delivery  of this  Guaranty  is a material
inducement  to the Agents and the Lenders in entering  into the Loan  Agreement.
Guarantor  hereby  acknowledges  that  there  are  no  conditions  to  the  full
effectiveness of this Guaranty.


<PAGE>


         19. This Guaranty is a Loan Document and,  therefore,  this Guaranty is
subject  to the  applicable  provisions  of the  Loan  Agreement,  all of  which
applicable  provisions are  incorporated  herein by reference the same as if set
forth herein  verbatim.  Moreover,  Guarantor  acknowledges and agrees that this
Guaranty is subject to the offset provisions in favor of the Lenders in the Loan
Agreement.

         20. Guarantor expressly assumes all responsibilities to remain informed
of the  financial  condition of Guarantor  and any  circumstances  affecting (a)
Guarantor's  ability  to  perform  under the Loan  Agreement  and the other Loan
Documents to which it is a party or (b) any collateral  securing all or any part
of the Guaranteed Indebtedness.

         21. In the event that Guarantor is entitled to receive any notice under
the  Uniform  Commercial  Code,  as it exists in the  state  governing  any such
notice, of the sale or other  disposition of any collateral  securing all or any
part of the Guaranteed Indebtedness or this Guaranty, reasonable notice shall be
deemed given when such notice is deposited  in the United  States mail,  postage
prepaid,  at the address for Guarantor  set forth on the signature  page of this
Guaranty,  five  days  prior to the date any  public  sale,  or after  which any
private sale,  of any such  collateral is to be held;  provided,  however,  that
notice  given in any other  reasonable  manner or at any other  reasonable  time
shall be sufficient.

         22. No delay on the part of the Administrative  Agent in exercising any
right  hereunder  or failure to exercise  the same shall  operate as a waiver of
such right.  In no event shall any waiver of the  provisions of this Guaranty be
effective unless the same be in writing and signed by the appropriate parties in
accordance with the Loan Agreement,  and then only in the specific  instance and
for the purpose given.

     23.  Nothing  contained  herein shall be construed as an  obligation on the
part of the Agents or the  Lenders  to extend or  continue  to extend  credit to
Guarantor.

         24.  Notwithstanding  any other  provision  of this  Guaranty or of any
instrument or agreement evidencing, governing or securing all or any part of the
Guaranteed   Indebtedness,   Guarantor  and  the  Administrative  Agent  by  its
acceptance hereof agree that no Guarantor shall ever be required or obligated to
pay  interest  in  excess of the  maximum  nonusurious  interest  rate as may be
authorized by applicable  law for the written  contracts  which  constitute  the
Guaranteed  Indebtedness.  It is the intention of Guarantor, the Agents, and the
Lenders to conform  strictly to the applicable  laws which limit interest rates,
and any of the aforesaid contracts for interest, if and to the extent payable by
Guarantor,  shall be held to be subject to reduction to the maximum  nonusurious
interest rate allowed under said law.

         25. THIS GUARANTY IS EXECUTED AND DELIVERED AS AN INCIDENT TO A LENDING
TRANSACTION  CONSUMMATED AND PERFORMABLE IN TRAVIS COUNTY,  TEXAS,  AND SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

         26.  Guarantor  shall pay on demand all reasonable  attorneys' fees and
all other costs and expenses  incurred by the Agents or any Lender in connection
with the enforcement or collection of this Guaranty.


<PAGE>


         27. THIS GUARANTY  EMBODIES THE FINAL,  ENTIRE  AGREEMENT OF GUARANTOR,
THE  AGENTS  AND  THE  LENDERS  WITH  RESPECT  TO  GUARANTOR'S  GUARANTY  OF THE
GUARANTEED INDEBTEDNESS AND RESTATES ANY AND ALL PRIOR COMMITMENTS,  AGREEMENTS,
REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER WRITTEN OR ORAL, RELATING TO THE
SUBJECT  MATTER HEREOF.  THIS GUARANTY IS INTENDED BY GUARANTOR,  THE AGENTS AND
THE LENDERS AS A FINAL AND COMPLETE EXPRESSION OF THE TERMS OF THE GUARANTY, AND
NO COURSE OF DEALING BETWEEN GUARANTOR,  THE AGENTS OR THE LENDERS, NO COURSE OF
PERFORMANCE,  NO TRADE PRACTICES,  AND NO EVIDENCE OF PRIOR,  CONTEMPORANEOUS OR
SUBSEQUENT  ORAL  AGREEMENTS OR DISCUSSIONS OR OTHER  EXTRINSIC  EVIDENCE OF ANY
NATURE SHALL BE USED TO CONTRADICT,  VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS
GUARANTY.  THERE ARE NO ORAL  AGREEMENTS  AMONG  GUARANTOR,  THE  AGENTS AND THE
LENDERS.

                     [REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGES FOLLOW.]


<PAGE>






         EXECUTED as of the 31st day of January, 2000.

                                                    GUARANTOR:
                                                    ---------

                                                    PRIME MEDICAL SERVICES, INC.
                                                    a Delaware corporation

                            By: /s/ Teena E. Belcik
                                 Teena E. Belcik

                                 Vice President-Treasurer

                                                  Address for Notices:

                                               1301 Capital of Texas Highway
                                               Suite C-300
                                               Austin, Texas 78746
                                               Attn: Treasurer
                                               Fax Number:  (512) 328-8510
                                               Telephone Number:  (512) 328-4554

<PAGE>



                               GUARANTY AGREEMENT

         WHEREAS,   PRIME  MEDICAL  SERVICES,   INC.,  a  Delaware   corporation
("Borrower"),  has entered into a Fourth  Amended and Restated Loan Agreement of
even date herewith with certain banks and other lending  institutions  which are
or may  from  time to time  become  signatories  thereto,  BANKBOSTON,  N.A.,  a
national banking  association,  as documentation  agent for itself and the other
Lenders,  BANK OF AMERICA,  N.A. ("B of A"), a national banking association,  as
administrative  agent  for  itself  and the  other  Lenders  (in such  capacity,
together with its  successors in such  capacity,  the  "Administrative  Agent"),
pursuant to which the Lenders have agreed to make a revolving credit loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Eighty-Six  Million and 00/100 Dollars at any time outstanding  ($86,000,000.00)
(such Fourth Amended and Restated Loan Agreement,  as may be amended,  extended,
restated,  supplemented  or modified from time to time,  the "Loan  Agreement");
terms defined in the Loan  Agreement and not otherwise  defined  herein are used
herein as defined therein; and

         WHEREAS,  the Agents and the Lenders have conditioned their obligations
under  the  Loan  Agreement  upon  the  execution  and  delivery  by  Guarantors
(hereinafter defined) of this Guaranty Agreement (this "Guaranty");

         NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which  are  hereby  acknowledged,  each  of  the  undersigned  (individually,  a
"Guarantor" and collectively,  the "Guarantors"),  hereby jointly and severally,
irrevocably and  unconditionally  guarantees to the Agents,  and to the Lenders,
the full and prompt  payment  and  performance  of the  Guaranteed  Indebtedness
(hereinafter defined), this Guaranty being upon the following terms:

         1 . The term "Guaranteed Indebtedness", as used herein means all of the
Obligations  and shall include any and all  post-petition  interest and expenses
(including  attorneys'  fees)  whether  or not  allowed  under  any  bankruptcy,
insolvency, or other similar law.

         2. This Guaranty  shall be an absolute,  continuing,  irrevocable,  and
unconditional  guaranty  of  payment  and  performance,  and not a  guaranty  of
collection,  and each Guarantor shall remain liable on its obligations hereunder
until the payment and  performance  in full of the Guaranteed  Indebtedness  and
termination of the Commitments. No set-off, counterclaim, recoupment, reduction,
or  diminution  of any  obligation,  or any defense of any kind or nature  which
Borrower may have against any Agent, any Lender or any other party, or which any
Guarantor may have against Borrower or any other party (other than the Agents or
any  Lender),  shall be  available  to, or shall be asserted  by, any  Guarantor
against  any  Agent,  any  Lender or any  subsequent  holder  of the  Guaranteed
Indebtedness   or  any  part  thereof  or  against  payment  of  the  Guaranteed
Indebtedness or any part thereof.

         3. Notwithstanding any contrary provision,  it is the intention of each
Guarantor,  Lenders,  and Agents that the amount of the Guaranteed  Indebtedness
guaranteed by each  Guarantor by this  Guaranty  shall be, but not in excess of,
the maximum amount permitted by fraudulent  conveyance,  fraudulent transfer, or
similar Laws applicable to such Guarantor. Accordingly, notwithstanding anything
to the contrary  contained in this Guaranty or any other agreement or instrument
executed in connection  with the payment of any of the Guaranteed  Indebtedness,
the amount of the  Guaranteed  Indebtedness  guaranteed by any Guarantor by this
Guaranty  shall be limited to an aggregate  amount  equal to the largest  amount
that  would  not  render  such  Guarantor's  obligations  hereunder  subject  to
avoidance  under  Section  548 of  the  United  States  Bankruptcy  Code  or any
comparable provision of any applicable state law.


<PAGE>





                                        7



<PAGE>


         4. If any  Guarantor  becomes  liable  for any  indebtedness  owing  by
Borrower  to any Agent or any Lender by  endorsement  or  otherwise,  other than
under this  Guaranty,  such  liability  shall not be in any manner  impaired  or
affected hereby, and the rights of the Agents and the Lenders hereunder shall be
cumulative  of any and all other rights that the Agents and the Lenders may ever
have  against  such  Guarantor.  The exercise by the Agents or any Lender of any
right or remedy hereunder or under any other instrument, or at law or in equity,
shall not preclude the  concurrent or subsequent  exercise of any other right or
remedy.

         5. In the event of default by Borrower in payment or performance of the
Guaranteed Indebtedness,  or any part thereof, when such Guaranteed Indebtedness
becomes due,  whether by its terms, by  acceleration,  or otherwise,  Guarantors
shall promptly pay the amount due thereon to the  Administrative  Agent, for the
benefit of the Lenders,  upon demand in lawful  currency of the United States of
America and it shall not be necessary for the Administrative  Agent, in order to
enforce  such  payment by  Guarantors,  first to  institute  suit or exhaust its
remedies against Borrower or others liable on such Guaranteed  Indebtedness,  or
to enforce any rights against any collateral which shall ever have been given to
secure such Guaranteed Indebtedness.

         6. If  acceleration  of the time for  payment of any amount  payable by
Borrower  under  the  Guaranteed  Indebtedness  is stayed  upon the  insolvency,
bankruptcy, or reorganization of Borrower, all such amounts otherwise subject to
acceleration under the terms of the Guaranteed Indebtedness shall nonetheless be
payable by Guarantors hereunder forthwith on demand by the Administrative Agent.


<PAGE>


         7.  Each  Guarantor  hereby  agrees  that its  obligations  under  this
Guaranty shall not be released,  discharged,  diminished,  impaired, reduced, or
affected for any reason or by the  occurrence of any event,  including,  without
limitation,  one or more of the following events,  whether or not with notice to
or the consent of such  Guarantor:  (a) the taking or accepting of collateral as
security for any or all of the  Guaranteed  Indebtedness  or the sale,  release,
surrender,  exchange,  or  subordination  of any  collateral  now  or  hereafter
securing any or all of the Guaranteed  Indebtedness;  (b) any partial release of
the  liability of any  Guarantor  hereunder,  or the full or partial  release of
Borrower or any other  guarantor from liability for any or all of the Guaranteed
Indebtedness;  (c) the dissolution,  insolvency,  or bankruptcy of Borrower, any
Guarantor,  or any other  party at any time liable for the payment of any or all
of the  Guaranteed  Indebtedness;  (d)  any  renewal,  extension,  modification,
waiver, amendment, or rearrangement of any or all of the Guaranteed Indebtedness
or any instrument,  document,  or agreement  evidencing,  securing, or otherwise
relating  to any or all of the  Guaranteed  Indebtedness;  (e)  any  adjustment,
indulgence,  forbearance,  waiver, settlement, or compromise that may be granted
or given by any Agent or any Lender to  Borrower,  any  Guarantor,  or any other
party  ever  liable  for  any or all of the  Guaranteed  Indebtedness;  (f)  the
subordination  of the payment of all or any part of the Guaranteed  Indebtedness
to the payment of any obligations, indebtedness, or liabilities which may be due
or become  due to any of the  Agents,  any of the  Lenders  or  others;  (g) the
application of any deposit balance,  fund, payment,  collections through process
of law or otherwise,  or other  collateral of Borrower to the  satisfaction  and
liquidation of the  indebtedness  or obligations of Borrower to Agents or any of
the Lenders, if any, not guaranteed under this Guaranty;  (h) the application of
any sums paid to any of the Agents or any of the Lenders by any  Guarantor,  any
other guarantor of all or any part of the Guaranteed  Indebtedness,  Borrower or
others to the Guaranteed  Indebtedness in such order and manner as any Agent may
determine  in  accordance  with  the Loan  Agreement;  (i) any  neglect,  delay,
omission,  failure,  or refusal of any Agent or any Lender to take or  prosecute
any  action  for the  collection  of any of the  Guaranteed  Indebtedness  or to
foreclose or take or prosecute  any action in  connection  with any  instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (j) the unenforceability or invalidity of any or
all of the Guaranteed Indebtedness or of any instrument,  document, or agreement
evidencing,  securing,  or  otherwise  relating to any or all of the  Guaranteed
Indebtedness; (k) any payment by Borrower or any other party to any Agent or any
Lender  is held to  constitute  a  preference  under  applicable  bankruptcy  or
insolvency law or if for any other reason any Agent or any Lender is required to
refund any payment or pay the amount thereof to someone else; (l) the settlement
or compromise of any of the Guaranteed  Indebtedness;  (m) the non-perfection of
any  security   interest  or  lien  securing  any  or  all  of  the   Guaranteed
Indebtedness;  (n) any impairment of any  collateral  securing any or all of the
Guaranteed Indebtedness;  (o) the failure of any Agent or any Lender to sell any
collateral securing any or all of the Guaranteed  Indebtedness in a commercially
reasonable  manner  or as  otherwise  required  by law;  (p) any  change  in the
corporate  existence,  structure,  or  ownership  of  Borrower;  (q)  any  other
circumstance  which  might  otherwise  constitute  a  defense  available  to, or
discharge  of,  Borrower;  (r) the  unenforceability  of all or any  part of the
Guaranteed  Indebtedness  against  Borrower  by  reason  of the  fact  that  the
Guaranteed  Indebtedness  exceeds the amount  permitted  by law;  (s) the act of
creating all or any part of the Guaranteed  Indebtedness  is ultra vires; or (t)
the officers  creating all or any part of the Guaranteed  Indebtedness  acted in
excess of their authority.

     8. Each  Guarantor  hereby  represents  and  warrants to the Agents and the
Lenders the following:

               (a) This Guaranty may reasonably be expected to benefit, directly
          or indirectly, each Guarantor.

               (b)  Each  Guarantor  is  familiar  with,  and has  independently
          reviewed the books and records regarding,  the financial  condition of
          Borrower  and is  familiar  with the  value of any and all  collateral
          intended  to be  security  for the  payment  of all or any part of the
          Guaranteed  Indebtedness.  However,  no  Guarantor  is relying on such
          financial  condition or collateral as an inducement to enter into this
          Guaranty.

                  (c) Each  Guarantor has adequate means to obtain from Borrower
         on a continuing basis information concerning the financial condition of
         Borrower,  and no  Guarantor is relying on the Agents or the Lenders to
         provide such information to any Guarantor either now or in the future.

                  (d) Each  Guarantor  has the power and  authority  to execute,
         deliver, and perform this Guaranty and any other agreements executed by
         such Guarantor contemporaneously herewith, and the execution, delivery,
         and performance of this Guaranty and any other  agreements  executed by
         each Guarantor  contemporaneously  herewith do not and will not violate
         (i) any agreement or  instrument to which any Guarantor is a party,  or
         (ii) any law, rule, regulation,  or order of any Governmental Authority
         to which any Guarantor is subject.

                  (e) Neither the Agents,  the Lenders,  nor any other party has
         made any  representation,  warranty,  or statement to any  Guarantor in
         order to induce any Guarantor to execute this Guaranty.

                  (f) The financial  statements and other financial  information
         regarding Guarantors heretofore and hereafter delivered to any Agent or
         any Lender are and shall be true and correct in all  material  respects
         and fairly present the financial position of Guarantors as of the dates
         thereof,  and no material  adverse change has occurred in the financial
         condition of any Guarantor as reflected in those financial disclosures.

                  (g) As of the date  hereof,  and after  giving  effect to this
         Guaranty and the obligations  evidenced  hereby,  (i) each Guarantor is
         and will be Solvent (to the extent  necessary,  taking into account any
         rights of contribution,  reimbursement and subrogation),  (ii) the fair
         saleable value of each Guarantor's  assets exceeds and will continue to
         exceed  its  liabilities  (both  fixed  and  contingent),   (iii)  each
         Guarantor  is and  will  continue  to be able to pay its  debts as they
         mature,  and  (iv)  each  Guarantor  has  and  will  continue  to  have
         sufficient capital to carry on its business and all businesses in which
         it is about to engage.

               (h) All  representations and warranties about each Guarantor made
          in the Loan Agreement are true and correct.

         9. Each Guarantor  covenants and agrees that, as long as the Guaranteed
Indebtedness or any part thereof is outstanding or any Lender has any Commitment
under the Loan Agreement:


<PAGE>


                  (a) No Guarantor shall, so long as its obligations  under this
         Guaranty  continue,  transfer  or pledge  any  material  portion of its
         assets for less than full and adequate consideration.

                  (b)   Each   Guarantor   shall   promptly   furnish   to   the
         Administrative  Agent at any time and from time to time such  financial
         statements and other financial  information as the Administrative Agent
         may require,  in form and substance  satisfactory to the Administrative
         Agent.

                  (c) Each Guarantor  shall comply with all terms and provisions
         of the Loan Documents that apply to such Guarantor.

                  (d) Each Guarantor  shall promptly  inform the  Administrative
         Agent of (i) any litigation or governmental  investigation against such
         Guarantor  or  affecting  any  security  for  all  or any  part  of the
         Guaranteed   Indebtedness   or  this  Guaranty   which,  if  determined
         adversely,  might have a material  adverse  effect  upon the  financial
         condition  of such  Guarantor  or upon such  security  or might cause a
         default under any of the Loan Documents,  (ii) any claim or controversy
         which  might  become the  subject of such  litigation  or  governmental
         investigation,  and (iii) any material  adverse change in the financial
         condition of Guarantor.

         10. (a) Each Guarantor hereby agrees that the Subordinated Indebtedness
(hereinafter defined) shall be subordinate and junior in right of payment to the
prior payment in full of all Guaranteed Indebtedness,  and each Guarantor hereby
assigns the  Subordinated  Indebtedness  to the  Administrative  Agent,  for the
benefit of the Lenders, as security for the Guaranteed Indebtedness. If any sums
shall be paid to any  Guarantor  by  Borrower  or any other  person or entity on
account of the  Subordinated  Indebtedness,  such sums shall be held in trust by
such Guarantor for the benefit of the  Administrative  Agent and shall forthwith
be paid to the  Administrative  Agent  without  affecting  the  liability of any
Guarantor under this Guaranty and may be applied by the Administrative Agent and
the Lenders against the Guaranteed  Indebtedness in such order and manner as the
Administrative  Agent and the Lenders may  determine  in their sole  discretion.
Upon the request of the  Administrative  Agent,  each  Guarantor  shall execute,
deliver,  and endorse to the Administrative Agent such documents and instruments
as the Administrative  Agent may request to perfect,  preserve,  and enforce its
rights  hereunder.  For  purposes  of  this  Guaranty,  the  term  "Subordinated
Indebtedness" means all indebtedness,  liabilities,  and obligations of Borrower
to any Guarantor,  whether such indebtedness,  liabilities,  and obligations now
exist or are hereafter incurred or arise, or whether the obligations of Borrower
thereon are direct, indirect, contingent, primary, secondary, several, joint and
several,   or  otherwise,   and  irrespective  of  whether  such   indebtedness,
liabilities,  or obligations are evidenced by a note, contract, open account, or
otherwise,  and  irrespective  of the  person or  persons  in whose  favor  such
indebtedness, obligations, or liabilities may, at their inception, have been, or
may hereafter be created, or the manner in which they have been or may hereafter
be acquired by any Guarantor.

                  (b) Each  Guarantor  agrees  that any and all liens,  security
interests, judgment liens, charges, or other encumbrances upon Borrower's assets
securing payment of any Subordinated  Indebtedness  shall be and remain inferior
and  subordinate  to any and all  liens,  security  interests,  judgment  liens,
charges,  or other  encumbrances  upon Borrower's assets securing payment of the
Guaranteed  Indebtedness  or  any  part  thereof,  regardless  of  whether  such
encumbrances  in favor of any Guarantor or the  Administrative  Agent  presently
exist or are hereafter created or attached. Without the prior written consent of
the Lenders,  no Guarantor  shall (i) file suit against  Borrower or exercise or
enforce  any  other  creditor's  right it may  have  against  Borrower,  or (ii)
foreclose, repossess, sequester, or otherwise take steps or institute any action
or  proceedings   judicial  or  otherwise,   including  without  limitation  the
commencement  of, or joinder  in, any  liquidation,  bankruptcy,  rearrangement,
debtor's  relief or  insolvency  proceeding)  to  enforce  any  liens,  security
interests,  collateral  rights,  judgments  or  other  encumbrances  held by any
Guarantor on assets of Borrower.


<PAGE>


                  (c)   In  the   event   of   any   receivership,   bankruptcy,
reorganization,  rearrangement,  debtor's relief, or other insolvency proceeding
involving Borrower as debtor,  the Administrative  Agent shall have the right to
prove and vote any claim  under the  Subordinated  Indebtedness  and to  receive
directly from the  receiver,  trustee or other court  custodian  all  dividends,
distributions,  and payments made in respect of the  Subordinated  Indebtedness.
The  Administrative  Agent  and  the  Lenders  may  apply  any  such  dividends,
distributions,  and payments  against the Guaranteed  Indebtedness in such order
and manner as the  Administrative  Agent and the Lenders may  determine in their
sole discretion.

                  (d) Each Guarantor agrees that all promissory notes,  accounts
receivable, ledgers, records, or any other evidence of Subordinated Indebtedness
shall contain a specific written notice thereon that the indebtedness  evidenced
thereby is subordinated under the terms of this Guaranty.

         11. Each  Guarantor  waives (a)  promptness,  diligence,  and notice of
acceptance  of this  Guaranty  and notice of the  incurring  of any  obligation,
indebtedness,  or  liability  to which  this  Guaranty  applies or may apply and
waives presentment for payment, notice of nonpayment, protest, demand, notice of
protest,  notice of  intent to  accelerate,  notice of  acceleration,  notice of
dishonor,  diligence in enforcement,  and indulgences of every kind, and (b) the
taking  of any other  action  by the  Administrative  Agent,  including  without
limitation,  giving any notice of default or any other  notice to, or making any
demand on,  Borrower,  any other  guarantor of all or any part of the Guaranteed
Indebtedness  or any other party.  To the maximum extent lawful,  each Guarantor
waives all rights by which it might be  entitled  to require  suit on an accrued
right of action in  respect  of any  Guaranteed  Indebtedness  or  require  suit
against  Borrower  or  others,  whether  arising  under  ss.  34.02 of the Texas
Business  and  Commerce  Code,  as  amended  (regarding  its  right  to  require
Administrative  Agent or Lenders  to sue  Borrower  on  accrued  right of action
following its written notice to Administrative Agent or Lenders),  ss. 17.001 of
the Texas Civil Practice and Remedies Code, as amended (allowing suit against it
without suit  against  Borrower,  but  precluding  entry of judgment  against it
before entry of judgment against Borrower),  Rule 31 of the Texas Rules of Civil
Procedure,  as  amended  (requiring  Administrative  Agent  or  Lenders  to join
Borrower in any suit  against it unless  judgment  has been  previously  entered
against Borrower), or otherwise.

         12. In addition  to any other  waivers,  agreements  and  covenants  of
Guarantors set forth herein,  each Guarantor  hereby further waives and releases
all claims,  causes of action,  defenses  and offsets for any act or omission of
the Administrative Agent, its directors, officers, employees, representatives or
agents in  connection  with the  Administrative  Agent's  administration  of the
Guaranteed   Indebtedness,   except  for  the  Administrative   Agent's  willful
misconduct and gross negligence.

         13. This Guaranty shall  continue to be effective or be reinstated,  as
the case may be, if at any time any payment of all or any part of the Guaranteed
Indebtedness  is  rescinded  or must  otherwise  be returned by any Agent or any
Lender upon the  insolvency,  bankruptcy,  or  reorganization  of Borrower,  any
Guarantor,   any  other   guarantor  of  all  or  any  part  of  the  Guaranteed
Indebtedness, or otherwise, all as though such payment had not been made.

         14. Any acknowledgment or new promise,  whether by payment of principal
or  interest  or  otherwise  and  whether  by  Borrower  or  others   (including
Guarantors),  with respect to any of the Guaranteed  Indebtedness  shall, if the
statute of  limitations  in favor of any  Guarantor  against the  Administrative
Agent or any  Lender  shall  have  commenced  to run,  toll the  running of such
statute of limitations  and, if the period of such statute of limitations  shall
have expired, prevent the operation of such statute of limitations.


<PAGE>


         15. This  Guaranty is for the benefit of the Agents and the Lenders and
their  respective  successors and assigns,  and in the event of an assignment of
the  Guaranteed  Indebtedness,  or any part  thereof,  the rights  and  benefits
hereunder,  to the extent  applicable to the  indebtedness  so assigned,  may be
transferred  with  such  indebtedness.  This  Guaranty  is  binding  not only on
Guarantors, but on each Guarantor's successors and assigns.

         16.  Each  Guarantor  recognizes  that the Agents and the  Lenders  are
relying upon this Guaranty and the  undertakings of each Guarantor  hereunder in
making  extensions  of credit to Borrower  under the Loan  Agreement and further
recognizes  that the  execution  and  delivery  of this  Guaranty  is a material
inducement  to the Agents and the Lenders in entering  into the Loan  Agreement.
Each  Guarantor  hereby  acknowledges  that there are no  conditions to the full
effectiveness of this Guaranty.

         17. This Guaranty is a Loan Document and,  therefore,  this Guaranty is
subject  to the  applicable  provisions  of the  Loan  Agreement,  all of  which
applicable  provisions are  incorporated  herein by reference the same as if set
forth herein  verbatim.  Moreover,  each Guarantor  acknowledges and agrees that
this Guaranty is subject to the offset provisions in favor of the Lenders in the
Loan Agreement.

         18. Each Guarantor  expressly  assumes all  responsibilities  to remain
informed of the financial condition of Borrower and any circumstances  affecting
(a)  Borrower's  ability to perform under the Loan  Agreement and the other Loan
Documents to which it is a party or (b) any collateral  securing all or any part
of the Guaranteed Indebtedness.

         19. In the event that any  Guarantor  is entitled to receive any notice
under the Uniform  Commercial Code, as it exists in the state governing any such
notice, of the sale or other  disposition of any collateral  securing all or any
part of the Guaranteed Indebtedness or this Guaranty, reasonable notice shall be
deemed given when such notice is deposited  in the United  States mail,  postage
prepaid,  at the address for Guarantor  set forth on the signature  page of this
Guaranty,  five  days  prior to the date any  public  sale,  or after  which any
private sale,  of any such  collateral is to be held;  provided,  however,  that
notice  given in any other  reasonable  manner or at any other  reasonable  time
shall be sufficient.

         20. No delay on the part of the Administrative  Agent in exercising any
right  hereunder  or failure to exercise  the same shall  operate as a waiver of
such right.  In no event shall any waiver of the  provisions of this Guaranty be
effective unless the same be in writing and signed by the appropriate parties in
accordance with the Loan Agreement,  and then only in the specific  instance and
for the purpose given.

     21.  Nothing  contained  herein shall be construed as an  obligation on the
part of the Agents or the  Lenders  to extend or  continue  to extend  credit to
Borrower.

         22.  Notwithstanding  any other  provision  of this  Guaranty or of any
instrument or agreement evidencing, governing or securing all or any part of the
Guaranteed  Indebtedness,  each  Guarantor and the  Administrative  Agent by its
acceptance hereof agree that no Guarantor shall ever be required or obligated to
pay  interest  in  excess of the  maximum  nonusurious  interest  rate as may be
authorized by applicable  law for the written  contracts  which  constitute  the
Guaranteed Indebtedness.  It is the intention of Guarantors, the Agents, and the
Lenders to conform  strictly to the applicable  laws which limit interest rates,
and any of the aforesaid contracts for interest, if and to the extent payable by
Guarantors,  shall be held to be subject to reduction to the maximum nonusurious
interest rate allowed under said law.

         23. THIS GUARANTY IS EXECUTED AND DELIVERED AS AN INCIDENT TO A LENDING
TRANSACTION  CONSUMMATED AND PERFORMABLE IN TRAVIS COUNTY,  TEXAS,  AND SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.


<PAGE>


         24. Each Guarantor  shall pay on demand all reasonable  attorneys' fees
and all other  costs  and  expenses  incurred  by the  Agents  or any  Lender in
connection with the enforcement or collection of this Guaranty.

         25.  Guarantors  (other than Prime RVC, Inc.,  which has not previously
executed  any guaranty of the  Guaranteed  Indebtedness)  acknowledge  that this
Guaranty has been given in amendment,  renewal,  restatement and confirmation of
Guarantor's  obligations,  covenants,  and agreements  contained in the Guaranty
Agreements  previously executed by certain Guarantors in favor of Administrative
Agent and the Lenders,  including,  without  limitation,  those dated August 17,
1995,  April 26,  1996,  March 31,  1997,  and  April  20,  1998 (the  "Previous
Guaranties"). Guarantors further confirm and agree that neither the execution of
the Loan  Agreement  or any other Loan  Document,  nor the  consummation  of the
transactions described therein, shall in any way affect the liability of certain
Guarantors under the Previous Guaranties,  and the obligations  evidenced by the
Previous Guaranties  continue in full force and effect as modified,  amended and
restated by the terms contained herein.

         26. THIS GUARANTY  EMBODIES THE FINAL,  ENTIRE AGREEMENT OF GUARANTORS,
THE  AGENTS  AND  THE  LENDERS  WITH  RESPECT  TO  GUARANTORS'  GUARANTY  OF THE
GUARANTEED INDEBTEDNESS AND RESTATES ANY AND ALL PRIOR COMMITMENTS,  AGREEMENTS,
REPRESENTATIONS,  AND  UNDERSTANDINGS,  WHETHER WRITTEN OR ORAL, RELATING TO THE
SUBJECT MATTER HEREOF.  THIS GUARANTY IS INTENDED BY GUARANTORS,  THE AGENTS AND
THE LENDERS AS A FINAL AND COMPLETE EXPRESSION OF THE TERMS OF THE GUARANTY, AND
NO COURSE OF DEALING BETWEEN ANY GUARANTOR, THE AGENTS OR THE LENDERS, NO COURSE
OF PERFORMANCE, NO TRADE PRACTICES, AND NO EVIDENCE OF PRIOR, CONTEMPORANEOUS OR
SUBSEQUENT  ORAL  AGREEMENTS OR DISCUSSIONS OR OTHER  EXTRINSIC  EVIDENCE OF ANY
NATURE SHALL BE USED TO CONTRADICT,  VARY, SUPPLEMENT OR MODIFY ANY TERM OF THIS
GUARANTY.  THERE ARE NO ORAL  AGREEMENTS  AMONG  GUARANTORS,  THE AGENTS AND THE
LENDERS.

                     [REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGES FOLLOW.]


<PAGE>






         EXECUTED as of the 31st day of January, 2000.

GUARANTORS:
- ----------

PROSTATHERAPIES, INC.,
a Delaware corporation
LITHOTRIPTORS, INC.,
a North Carolina corporation
FASTSTART, INC.,
a North Carolina corporation
NATIONAL LITHOTRIPTORS ASSOCIATION,
a North Carolina corporation
R.R. LITHO, INC.,
a Delaware corporation
OHIO LITHO, INC.,
a Delaware corporation
MEDTECH INVESTMENT, INC.,
a North Carolina corporation
PRIME MEDICAL OPERATING, INC.,
a Delaware corporation
PRIME MANAGEMENT, INC.,
a Nevada corporation
PRIME LITHOTRIPTER OPERATIONS, INC.,
a New York corporation
PRIME DIAGNOSTIC SERVICES, INC.,
a Delaware corporation
PRIME LITHOTRIPSY SERVICES, INC.,
a New York corporation
PRIME DIAGNOSTIC CORP. OF FLORIDA,
a Delaware corporation
SUN MEDICAL TECHNOLOGIES, INC.,
a California corporation
PRIME PRACTICE MANAGEMENT, INC.,
a New York corporation
PRIME CARDIAC REHABILITATION SERVICES,
INC., a Delaware corporation
ALABAMA RENAL STONE INSTITUTE, INC.,
an Alabama corporation
PRIME KIDNEY STONE TREATMENT, INC.,
a New Jersey corporation
SUN ACQUISITION, INC.,
a California corporation
EXECUTIVE MEDICAL ENTERPRISES, INC.,
a Delaware corporation
PRIME RVC, INC.,
a Delaware corporation


                            By: /s/ Teena E. Belcik
                                 Teena E. Belcik
                                 Treasurer


<PAGE>






                         PRIME MEDICAL MANAGEMENT, L.P.,
                         a Delaware limited partnership

                           By:      Prime Medical Operating, Inc.,
                                    a Delaware corporation, its
                                    General Partner

                           By: /s/ Teena E. Belcik
                                      Teena E. Belcik
                                      Treasurer

                                               Address for Notices:

                                               1301 Capital of Texas Highway
                                               Suite C-300
                                               Austin, Texas 78746
                                               Attn: President
                                               Fax Number:  (512) 328-8510
                                               Telephone Number:  (512) 328-2892





                                                                            Note

                                      NOTE

$1,050,000.00               Dallas, Texas                       January 31, 2000


         FOR VALUE  RECEIVED,  the  undersigned,  PRIME  REFRACTIVE  MANAGEMENT,
L.L.C., a Delaware limited liability company  ("Maker"),  hereby promises to pay
to the order of GUARANTY FEDERAL BANK, F.S.B.  ("Payee"), at the offices of Bank
of America,  N.A.,  as  Administrative  Agent  (together  with any  successor as
provided in the Agreement,  hereinbelow defined, the "Administrative  Agent") at
901 Main Street,  Dallas, Texas 75202, on April 21, 2003, in lawful money of the
United States of America,  the  principal sum of ONE MILLION FIFTY  THOUSAND AND
NO/100  DOLLARS  ($1,050,000.00),  or so much  thereof  as may be  advanced  and
outstanding  hereunder  together with the interest on the outstanding  principal
balance from day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain Loan Agreement of even date herewith  among Maker,  Payee,
the Administrative Agent, BankBoston,  N.A., as Documentation Agent, and each of
the other  Lenders  which is or may become a party  thereto or any  successor or
assignee thereof (as the same may be amended, supplemented or modified from time
to time, the "Agreement") and is one of the Notes described therein. Capitalized
terms used and not otherwise  defined herein shall have the same meanings as set
forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>




                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

                                           PRIME REFRACTIVE MANAGEMENT, L.L.C.



                                           By: /s/ Teena E. Belcik
                                                   Teena E. Belcik
                                                  Vice President-Treasurer




                                                                            NOTE

$1,575,000.00                    Dallas, Texas                  January 31, 2000


         FOR VALUE  RECEIVED,  the  undersigned,  PRIME  REFRACTIVE  MANAGEMENT,
L.L.C., a Delaware limited liability company  ("Maker"),  hereby promises to pay
to the  order  of FLEET  NATIONAL  BANK  ("Payee"),  at the  offices  of Bank of
America,  N.A., as Administrative Agent (together with any successor as provided
in the Agreement,  hereinbelow defined, the "Administrative  Agent") at 901 Main
Street,  Dallas,  Texas 75202,  on April 21, 2003, in lawful money of the United
States of America,  the principal  sum of ONE MILLION FIVE HUNDRED  SEVENTY-FIVE
THOUSAND  AND  NO/100  DOLLARS  ($1,575,000.00),  or so much  thereof  as may be
advanced and outstanding hereunder together with the interest on the outstanding
principal balance from day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain Loan Agreement of even date herewith  among Maker,  Payee,
the Administrative Agent, BankBoston,  N.A., as Documentation Agent, and each of
the other  Lenders  which is or may become a party  thereto or any  successor or
assignee thereof (as the same may be amended, supplemented or modified from time
to time, the "Agreement") and is one of the Notes described therein. Capitalized
terms used and not otherwise  defined herein shall have the same meanings as set
forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>





                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

                                             PRIME REFRACTIVE MANAGEMENT, L.L.C.



                                              By: /s/ Teena E. Belcik
                                                        Teena E. Belcik
                                                        Vice President-Treasurer




                                                                            NOTE

$3,150,000.00                  Dallas, Texas                    January 31, 2000


         FOR VALUE  RECEIVED,  the  undersigned,  PRIME  REFRACTIVE  MANAGEMENT,
L.L.C., a Delaware limited liability company  ("Maker"),  hereby promises to pay
to the order of BANKBOSTON,  N.A. ("Payee"),  at the offices of Bank of America,
N.A., as  Administrative  Agent  (together with any successor as provided in the
Agreement,  hereinbelow defined, the "Administrative Agent") at 901 Main Street,
Dallas,  Texas 75202, on April 21, 2003, in lawful money of the United States of
America,  the  principal  sum of THREE  MILLION ONE HUNDRED  FIFTY  THOUSAND AND
NO/100  DOLLARS  ($3,150,000.00),  or so much  thereof  as may be  advanced  and
outstanding  hereunder  together with the interest on the outstanding  principal
balance from day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain Loan Agreement of even date herewith  among Maker,  Payee,
the Administrative Agent, BankBoston,  N.A., as Documentation Agent, and each of
the other  Lenders  which is or may become a party  thereto or any  successor or
assignee thereof (as the same may be amended, supplemented or modified from time
to time, the "Agreement") and is one of the Notes described therein. Capitalized
terms used and not otherwise  defined herein shall have the same meanings as set
forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>





                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

                                            PRIME REFRACTIVE MANAGEMENT, L.L.C.



                                               By: /s/ Teena E. Belcik
                                                     Teena E. Belcik
                                                     Vice President-Treasurer







                                                                            NOTE

$4,725,000.00                             Dallas, Texas         January 31, 2000


         FOR VALUE  RECEIVED,  the  undersigned,  PRIME  REFRACTIVE  MANAGEMENT,
L.L.C., a Delaware limited liability company  ("Maker"),  hereby promises to pay
to the order of BANK OF  AMERICA,  N.A.  ("Payee"),  at the  offices  of Bank of
America,  N.A., as Administrative Agent (together with any successor as provided
in the Agreement,  hereinbelow defined, the "Administrative  Agent") at 901 Main
Street,  Dallas,  Texas 75202,  on April 21, 2003, in lawful money of the United
States of America,  the principal sum of FOUR MILLION SEVEN HUNDRED  TWENTY-FIVE
THOUSAND  AND  NO/100  DOLLARS  ($4,725,000.00),  or so much  thereof  as may be
advanced and outstanding hereunder together with the interest on the outstanding
principal balance from day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain Loan Agreement of even date herewith  among Maker,  Payee,
the Administrative Agent, BankBoston,  N.A., as Documentation Agent, and each of
the other  Lenders  which is or may become a party  thereto or any  successor or
assignee thereof (as the same may be amended, supplemented or modified from time
to time, the "Agreement") and is one of the Notes described therein. Capitalized
terms used and not otherwise  defined herein shall have the same meanings as set
forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>




                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

                                           PRIME REFRACTIVE MANAGEMENT, L.L.C.



                                       By: /s/ Teena E. Belcik
                                                   Teena E. Belcik
                                                   Vice President-Treasurer




                                                                            NOTE

$2,100,000.00                           Dallas, Texas           January 31, 2000


         FOR VALUE  RECEIVED,  the  undersigned,  PRIME  REFRACTIVE  MANAGEMENT,
L.L.C., a Delaware limited liability company  ("Maker"),  hereby promises to pay
to the order of BANK ONE,  TEXAS,  N.A.  ("Payee"),  at the  offices  of Bank of
America,  N.A., as Administrative Agent (together with any successor as provided
in the Agreement,  hereinbelow defined, the "Administrative  Agent") at 901 Main
Street,  Dallas,  Texas 75202,  on April 21, 2003, in lawful money of the United
States of America,  the  principal  sum of TWO MILLION ONE HUNDRED  THOUSAND AND
NO/100  DOLLARS  ($2,100,000.00),  or so much  thereof  as may be  advanced  and
outstanding  hereunder  together with the interest on the outstanding  principal
balance from day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain Loan Agreement of even date herewith  among Maker,  Payee,
the Administrative Agent, BankBoston,  N.A., as Documentation Agent, and each of
the other  Lenders  which is or may become a party  thereto or any  successor or
assignee thereof (as the same may be amended, supplemented or modified from time
to time, the "Agreement") and is one of the Notes described therein. Capitalized
terms used and not otherwise  defined herein shall have the same meanings as set
forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>




                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

                                            PRIME REFRACTIVE MANAGEMENT, L.L.C.



                                            By: /s/ Teena E. Belcik
                                                 Teena E. Belcik
                                                 Vice President-Treasurer







                                                                            NOTE

$12,900,000.00              Dallas, Texas                       January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware corporation ("Maker"), hereby promises to pay to the order of BANK ONE,
TEXAS,  N.A.   ("Payee"),   at  the  offices  of  Bank  of  America,   N.A.,  as
Administrative  Agent (together with any successor as provided in the Agreement,
hereinbelow  defined,  the "Administrative  Agent") at 901 Main Street,  Dallas,
Texas 75202, on April 21, 2003, in lawful money of the United States of America,
the principal  sum of TWELVE  MILLION NINE HUNDERD  THOUSAND AND NO/100  DOLLARS
($12,900,000.00),  or so  much  thereof  as  may  be  advanced  and  outstanding
hereunder  together with the interest on the outstanding  principal balance from
day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>





                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                              PRIME MEDICAL SERVICES, INC.



                                                  By: /s/ Teena E. Belcik
                                                      Teena E. Belcik
                                                      Vice President-Treasurer










                                                                            NOTE

$8,600,000.00                            Dallas, Texas          January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware corporation  ("Maker"),  hereby promises to pay to the order of LASALLE
BANK, NATIONAL ASSOCIATION  ("Payee"),  at the offices of Bank of America, N.A.,
as  Administrative  Agent  (together  with  any  successor  as  provided  in the
Agreement,  hereinbelow defined, the "Administrative Agent") at 901 Main Street,
Dallas,  Texas 75202, on April 21, 2003, in lawful money of the United States of
America,  the  principal  sum of EIGHT  MILLION SIX HUNDERD  THOUSAND AND NO/100
DOLLARS  ($8,600,000.00),  or so much thereof as may be advanced and outstanding
hereunder  together with the interest on the outstanding  principal balance from
day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>




                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                          PRIME MEDICAL SERVICES, INC.



                                           By: /s/ Teena E. Belcik
                                               Teena E. Belcik
                                               Vice President-Treasurer










                                                                            NOTE

$8,600,000.00                        Dallas, Texas              January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware  corporation  ("Maker"),  hereby  promises  to  pay  to  the  order  of
COOPERATIVE CENTRALE  RAIFFEISEN-BOERENLEENBANK  B.A., "RABOBANK NEDERLAND", NEW
YORK  BRANCH   ("Payee"),   at  the  offices  of  Bank  of  America,   N.A.,  as
Administrative  Agent (together with any successor as provided in the Agreement,
hereinbelow  defined,  the "Administrative  Agent") at 901 Main Street,  Dallas,
Texas 75202, on April 21, 2003, in lawful money of the United States of America,
the  principal  sum of EIGHT  MILLION SIX HUNDERD  THOUSAND  AND NO/100  DOLLARS
($8,600,000.00), or so much thereof as may be advanced and outstanding hereunder
together with the interest on the outstanding  principal balance from day to day
remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>




                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                                 PRIME MEDICAL SERVICES, INC.



                                                 By: /s/ Teena E. Belcik
                                                      Teena E. Belcik
                                                      Vice President-Treasurer









                                                                            NOTE

$8,600,000.00             Dallas, Texas                         January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware  corporation  ("Maker"),  hereby promises to pay to the order of CREDIT
LYONNAIS NEW YORK BRANCH ("Payee"),  at the offices of Bank of America, N.A., as
Administrative  Agent (together with any successor as provided in the Agreement,
hereinbelow  defined,  the "Administrative  Agent") at 901 Main Street,  Dallas,
Texas 75202, on April 21, 2003, in lawful money of the United States of America,
the  principal  sum of EIGHT  MILLION SIX HUNDERD  THOUSAND  AND NO/100  DOLLARS
($8,600,000.00), or so much thereof as may be advanced and outstanding hereunder
together with the interest on the outstanding  principal balance from day to day
remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>





                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                                  PRIME MEDICAL SERVICES, INC.



                                                  By: /s/ Teena E. Belcik
                                                       Teena E. Belcik
                                                       Vice President-Treasurer










                                                                            NOTE

$5,375,000.00           Dallas, Texas                           January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware  corporation  ("Maker"),  hereby  promises to pay to the order of FLEET
NATIONAL  BANK  ("Payee"),   at  the  offices  of  Bank  of  America,  N.A.,  as
Administrative  Agent (together with any successor as provided in the Agreement,
hereinbelow  defined,  the "Administrative  Agent") at 901 Main Street,  Dallas,
Texas 75202, on April 21, 2003, in lawful money of the United States of America,
the principal sum of FIVE MILLION THREE HUNDERD SEVENTY-FIVE THOUSAND AND NO/100
DOLLARS  ($5,375,000.00),  or so much thereof as may be advanced and outstanding
hereunder  together with the interest on the outstanding  principal balance from
day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>




                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                         PRIME MEDICAL SERVICES, INC.



                                          By: /s/ Teena E. Belcik
                                                Teena E. Belcik
                                                Vice President-Treasurer





                                                                            NOTE

$8,600,000.00                      Dallas, Texas                January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware corporation ("Maker"),  hereby promises to pay to the order of IMPERIAL
BANK ("Payee"), at the offices of Bank of America, N.A., as Administrative Agent
(together with any successor as provided in the Agreement,  hereinbelow defined,
the "Administrative  Agent") at 901 Main Street,  Dallas,  Texas 75202, on April
21, 2003, in lawful money of the United States of America,  the principal sum of
EIGHT MILLION SIX HUNDERD  THOUSAND AND NO/100  DOLLARS  ($8,600,000.00),  or so
much  thereof as may be advanced and  outstanding  hereunder  together  with the
interest on the  outstanding  principal  balance from day to day  remaining,  as
herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>




                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                              PRIME MEDICAL SERVICES, INC.



                                              By: /s/ Teena E. Belcik
                                                  Teena E. Belcik
                                                  Vice President-Treasurer










                                                                            NOTE

$6,450,000.00                  Dallas, Texas                    January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware corporation ("Maker"),  hereby promises to pay to the order of GUARANTY
FEDERAL  BANK,  F.S.B.  ("Payee"),  at the offices of Bank of America,  N.A., as
Administrative  Agent (together with any successor as provided in the Agreement,
hereinbelow  defined,  the "Administrative  Agent") at 901 Main Street,  Dallas,
Texas 75202, on April 21, 2003, in lawful money of the United States of America,
the principal sum of SIX MILLION FOUR HUNDERD FIFTY  THOUSAND AND NO/100 DOLLARS
($6,450,000.00), or so much thereof as may be advanced and outstanding hereunder
together with the interest on the outstanding  principal balance from day to day
remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>



D-736095.1

                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         Note,  together  with all the other Notes issued on the date hereof are
given in renewal,  amendment,  and restatement,  but not extinguishment,  of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                                    PRIME MEDICAL SERVICES, INC.



                                                     By: /s/ Teena E. Belcik
                                                        Teena E. Belcik
                                                        Vice President-Treasurer









                                                                            Note

                                      NOTE

$16,125,000.00           Dallas, Texas                          January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware corporation  ("Maker"),  hereby promises to pay to the order of BANK OF
AMERICA,  N.A.  ("Payee"),   at  the  offices  of  Bank  of  America,  N.A.,  as
Administrative  Agent (together with any successor as provided in the Agreement,
hereinbelow  defined,  the "Administrative  Agent") at 901 Main Street,  Dallas,
Texas 75202, on April 21, 2003, in lawful money of the United States of America,
the principal sum of SIXTEEN MILLION ONE HUNDERD TWENTY-FIVE THOUSAND AND NO/100
DOLLARS ($16,125,000.00),  or so much thereof as may be advanced and outstanding
hereunder  together with the interest on the outstanding  principal balance from
day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>





                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                                  PRIME MEDICAL SERVICES, INC.



                                                  By: /s/ Teena E. Belcik
                                                       Teena E. Belcik
                                                       Vice President-Treasurer










                                      NOTE

$10,750,000.00               Dallas, Texas                      January 31, 2000


         FOR VALUE RECEIVED,  the undersigned,  PRIME MEDICAL SERVICES,  INC., a
Delaware  corporation  ("Maker"),  hereby  promises  to  pay  to  the  order  of
BANKBOSTON,  N.A.  ("Payee"),  at the  offices  of Bank  of  America,  N.A.,  as
Administrative  Agent (together with any successor as provided in the Agreement,
hereinbelow  defined,  the "Administrative  Agent") at 901 Main Street,  Dallas,
Texas 75202, on April 21, 2003, in lawful money of the United States of America,
the principal sum of TEN MILLION SEVEN HUNDERD FIFTY THOUSAND AND NO/100 DOLLARS
($10,750,000.00),  or so  much  thereof  as  may  be  advanced  and  outstanding
hereunder  together with the interest on the outstanding  principal balance from
day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain  Fourth  Amended and Restated Loan  Agreement of even date
herewith among Maker,  Payee, the  Administrative  Agent,  BankBoston,  N.A., as
Documentation  Agent,  and each of the other  Lenders  which is or may  become a
party thereto or any successor or assignee  thereof (as the same may be amended,
supplemented or modified from time to time, the  "Agreement")  and is one of the
Notes described therein. Capitalized terms used and not otherwise defined herein
shall have the same meanings as set forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>





                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

         This Note,  together with all the other Notes issued on the date hereof
are given in renewal, amendment, and restatement, but not extinguishment, of the
Revolving  Credit  Notes  issued  under  the Third  Amended  and  Restated  Loan
Agreement,  dated as of April  20,  1998,  among  Maker,  Administrative  Agent,
BankBoston,  N.A., as  Documentation  Agent, and each of the other lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Second Amended
and Restated Loan Agreement dated as of March 31, 1997 among Maker,  NationsBank
as predecessor  Documentation Agent, BankBoston,  as predecessor  Administrative
Agent, and each of the other lenders party thereto, which were given in renewal,
amendment,  increase, and restatement, but not extinguishment,  of the Revolving
Credit Notes issued under the Amended and Restated  Loan  Agreement  dated as of
April 26, 1996 among Maker,  NationsBank  as  predecessor  Documentation  Agent,
BankBoston,  as predecessor  Administrative Agent, and each of the lenders party
thereto, which were given in renewal, amendment,  increase, and restatement, but
not extinguishment of the Revolving Credit Notes issued under the Loan Agreement
dated  as  of  November  28,  1994  among  Maker,  BankBoston,   as  predecessor
Administrative Agent and the banks named therein.

                                       PRIME MEDICAL SERVICES, INC.



                                    By: /s/ Teena E. Belcik
                                            Teena E. Belcik
                                            Vice President-Treasurer










                                      NOTE

$1,400,000.00          Dallas, Texas                            January 31, 2000


         FOR VALUE  RECEIVED,  the  undersigned,  PRIME  REFRACTIVE  MANAGEMENT,
L.L.C., a Delaware limited liability company  ("Maker"),  hereby promises to pay
to the order of LASALLE BANK, NATIONAL ASSOCIATION ("Payee"),  at the offices of
Bank of America,  N.A., as Administrative  Agent (together with any successor as
provided in the Agreement,  hereinbelow defined, the "Administrative  Agent") at
901 Main Street,  Dallas, Texas 75202, on April 21, 2003, in lawful money of the
United States of America, the principal sum of ONE MILLION FOUR HUNDRED THOUSAND
AND NO/100  DOLLARS  ($1,400,000.00),  or so much thereof as may be advanced and
outstanding  hereunder  together with the interest on the outstanding  principal
balance from day to day remaining, as herein specified.

         This Note has been  executed  and  delivered  by Maker  pursuant to the
terms of that certain Loan Agreement of even date herewith  among Maker,  Payee,
the Administrative Agent, BankBoston,  N.A., as Documentation Agent, and each of
the other  Lenders  which is or may become a party  thereto or any  successor or
assignee thereof (as the same may be amended, supplemented or modified from time
to time, the "Agreement") and is one of the Notes described therein. Capitalized
terms used and not otherwise  defined herein shall have the same meanings as set
forth in the Agreement.

         Reference is hereby made to the Agreement for provisions affecting this
Note, including, without limitation,  provisions regarding payments, prepayments
(optional and mandatory),  Events of Default and the Administrative  Agent's and
Payee's right as a result of the occurrence thereof.

         The outstanding  principal  balance hereof shall bear interest prior to
maturity at a varying rate per annum which shall from day to day be equal to the
lesser of (a) the Maximum Rate, or (b) the Applicable Rate in effect from day to
day,  each  such  change in the rate of  interest  charged  hereunder  to become
effective,  without notice to Maker, on the effective date of each change in the
Applicable Rate or the Maximum Rate, as the case may be; provided,  however,  if
at any time the Applicable  Rate shall exceed the Maximum Rate,  thereby causing
the interest rate hereon to be limited to the Maximum Rate,  then any subsequent
reduction in the  Applicable  Rate shall not reduce the rate of interest  hereon
below the Maximum Rate until the total amount of interest  accrued hereon equals
the amount of interest which would have accrued  hereon if the  Applicable  Rate
had at all times been in effect.  Accrued and unpaid interest on this Note shall
be due and  payable  on each  Payment  Date  and on the  Termination  Date.  All
past-due principal and interest shall bear interest as the Default Rate.


<PAGE>





                                        3


         Regardless of any  provision  contained in any Loan  Document,  neither
Administrative  Agent nor any Lender  shall ever be entitled  to  contract  for,
charge, take, reserve,  receive, or apply, as interest on all or any part of the
Obligations,  any amount in excess of the Maximum Rate,  and, if Lenders ever do
so, then such  excess  shall be deemed a partial  prepayment  of  principal  and
treated  hereunder as such and any remaining  excess shall be refunded to Maker.
In determining if the interest paid or payable  exceeds the Maximum Rate,  Maker
and Lenders shall,  to the maximum extent  permitted  under  applicable Law, (a)
treat all  Advances as but a single  extension  of credit (and Lenders and Maker
agree that such is the case and that provision  herein for multiple  Advances is
for convenience only), (b) characterize any nonprincipal  payment as an expense,
fee, or premium rather than as interest,  (c) exclude voluntary  prepayments and
the effects thereof, and (d) amortize,  prorate,  allocate, and spread the total
amount of interest  throughout the entire  contemplated term of the Obligations.
However,  if the  Obligations are paid and performed in full prior to the end of
the full contemplated term thereof,  and if the interest received for the actual
period of existence  thereof  exceeds the Maximum  Amount,  Lenders shall refund
such excess,  and, in such event,  Lenders shall not, to the extent permitted by
Law,  be subject to any  penalties  provided  by any laws for  contracting  for,
charging,  taking,  reserving,  or  receiving  interest in excess of the Maximum
Amount.  The "Maximum Rate" or the "Maximum  Amount," mean the "weekly  ceiling"
from time to time in effect under Texas Finance Code ss. 303.305, as amended.

         Upon the occurrence of an Event of Default,  the  Administrative  Agent
may (and if directed by the Required  Lenders,  shall) declare the entire unpaid
principal  of and  accrued  interest  on this Note  immediately  due and payable
without notice, demand or presentment,  all of which are hereby waived, and upon
such  declaration,  the same  shall  become  and  shall be  immediately  due and
payable,  and the  Administrative  Agent  shall have the right to  foreclose  or
otherwise  enforce all Liens or security  interests  securing payment hereof, or
any part  hereof,  and  offset  against  this  Note any sum or sums  owed by the
Administrative  Agent,  Payee or the  holder  hereof  to Maker.  Failure  of the
Administrative  Agent,  Payee or the holder hereof to exercise this option shall
not constitute a waiver of the right to exercise the same upon the occurrence of
a subsequent Event of Default.

         If the  Administrative  Agent,  Payee or the holder hereof  expends any
effort in any attempt to enforce  payment of all or any part or  installment  of
any sum due the holder  hereunder,  or if this Note is placed in the hands of an
attorney for collection,  or if it is collected  through any legal  proceedings,
Maker agrees to pay all costs, expenses, and fees incurred by the Administrative
Agent, or the holder, including reasonable attorneys' fees.

         This Note shall be governed by and  construed  in  accordance  with the
laws of the  State of Texas  and the  applicable  laws of the  United  States of
America.

         Except as provided in the Agreement,  Maker and each surety, guarantor,
endorser,  and other party ever liable for payment of any sums of money  payable
on this Note  jointly  and  severally  waive  notice,  presentment,  demand  for
payment,  protest,  notice of protest and  non-payment  or  dishonor,  notice of
acceleration,  notice  of  intent to  accelerate,  notice  of intent to  demand,
diligence in  collecting,  grace,  and all other  formalities  of any kind,  and
consent to all  extensions  without notice for any period or periods of time and
partial payments, before or after maturity, and any impairment of any Collateral
securing this Note, all without prejudice to the Administrative  Agent, Payee or
the holder. The Administrative  Agent, Payee and the holder shall similarly have
the  right to deal in any way,  at any time,  with one or more of the  foregoing
parties  without  notice to any  other  party,  and to grant any such  party any
extensions  of time for  payment of any of said  indebtedness,  or to release or
substitute  part or all of the  Collateral  securing  this Note, or to grant any
other indulgences or forbearances whatsoever,  without notice to any other party
and without in any way affecting the personal liability of any party hereunder.


<PAGE>


         Maker hereby authorizes the Administrative  Agent, Payee and the holder
hereof to  endorse on the  Schedule  attached  to this Note or any  continuation
thereof  or to record  in their  internal  records  all  Advances  made to Maker
hereunder  and all  payments  made on account of the  principal  thereof,  which
endorsements  or recordings  shall be prima facie evidence as to the outstanding
principal  amount  of  this  Note;   provided,   however,  any  failure  by  the
Administrative Agent, Payee or the holder hereof to make any such endorsement or
recording shall not limit or otherwise affect the obligations of Maker under the
Agreement or this Note.

                                 PRIME REFRACTIVE MANAGEMENT, L.L.C.



                            By: /s/ Teena E. Belcik
                                 Teena E. Belcik
                                 Vice President-Treasurer

                             CONTRIBUTION AGREEMENT


                                      Among


                       BARNET DULANEY EYE CENTER, P.L.L.C.


                             DAVID D. DULANEY, M.D.,


                             RONALD W. BARNET, M.D.,


                                 MARK ROSENBERG,


                          PRIME MEDICAL SERVICES, INC.,


                         PRIME MEDICAL OPERATING, INC.,


                            LASIK INVESTORS, L.L.C.,


                         PRIME/BDR ACQUISITION, L.L.C.,


                                       And


                         PRIME/BDEC ACQUISITION, L.L.C.



                             Dated September 1, 1999








<PAGE>


                             CONTRIBUTION AGREEMENT

         This  Contribution  Agreement (this  "Agreement") is entered into to be
effective as of September 1, 1999 (the  "Effective  Time"),  among Prime Medical
Operating,  Inc., a Delaware corporation ("Prime"), Prime Medical Services, Inc.
a Delaware corporation ("PMSI"), Barnet Dulaney Eye Center, P.L.L.C., an Arizona
professional  limited  liability company  ("BDEC"),  LASIK Investors,  L.L.C., a
Delaware  limited  liability   company   ("LASIK"),   David  D.  Dulaney,   M.D.
("Dulaney"),  Ronald W. Barnet, M.D. ("Barnet"),  Mark Rosenberg  ("Rosenberg"),
Prime/BDR Acquisition,  L.L.C., a Delaware limited liability company ("Newco I")
and Prime/BDEC Acquisition, L.L.C., a Delaware limited liability company ("Newco
II"). BDEC, LASIK, Dulaney,  Barnet and Rosenberg are also sometimes referred to
collectively herein as the "Sellers" and individually as a "Seller."

         The parties hereto agree as follows:

                                                     ARTICLE I

                                          Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement, (a) Prime agrees to purchase, as of the Effective Time, from BDEC, an
undivided  sixty  percent  (60%)  interest  in (i) the  Assets  (as  hereinafter
defined)  and (ii) the  business  conducted  using  the  Assets,  excluding  the
practice of medicine in all cases (the "Business"),  for $8,807,000 in cash (the
"Purchase  Price),  together with warrants,  in substantially  the form attached
hereto as Exhibit A (the "Primary Warrants"),  entitling BDEC to purchase 29,356
shares of $0.01 par value  common  stock of PMSI,  at one  hundred  ten  percent
(110%) of PMSI's  closing  share price as quoted by NASDAQ on the Closing  Date;
(b) Prime  agrees to  contribute  to Newco II,  as of the  Effective  Time,  the
undivided  sixty percent (60%) interest in the Assets and Business  purchased by
Prime,  and will receive a sixty percent (60%)  ownership  interest in Newco II;
(c) BDEC agrees to contribute, as of the Effective Time, the remaining undivided
forty percent  (40%)  interest in the Assets and Business to Newco II; (d) Prime
shall  acquire,  as of the  Effective  Time,  a sixty  percent  (60%)  ownership
interest in Newco I; and (e) LASIK shall  acquire,  as of the Effective  Time, a
forty percent (40%) interest in Newco I. The Purchase Price will be allocated to
the Assets in accordance  with Schedule 1.1 attached  hereto.  The parties agree
that:

     (w) immediately  prior to the Closing,  all of the  outstanding  membership
interests  of Newco I shall  be  owned by  LASIK,  and,  immediately  after  the
Closing,  Prime  shall  own  sixty  percent  (60%)  of all  of  the  outstanding
membership  interests of Newco I, and LASIK shall own forty percent (40%) of all
of the outstanding membership interests of Newco I;

     (x) immediately  prior to the Closing,  all of the  outstanding  membership
interests  of Newco II shall be  owned  by  BDEC,  and,  immediately  after  the
Closing,  Prime  shall  own  sixty  percent  (60%)  of all  of  the  outstanding
membership  interests of Newco II, and BDEC shall own forty percent (40%) of all
of the outstanding membership interests of Newco II;

     (y) prior to the  Effective  Time,  Prime and LASIK shall have executed the
limited liability company  agreement,  in the form attached hereto as Exhibit B,
and any other organizational documents of Newco I. ---------

     (z) prior to the  Effective  Time,  Prime and BDEC shall have  executed the
limited liability company  agreement,  in the form attached hereto as Exhibit C,
and any other organizational documents of Newco II; and ---------

         The  organizational  documents of Newco I and Newco II are  hereinafter
collectively referred to as the "Organizational Documents."

     1.2 Closing.  The closing of the  transactions  contemplated by Section 1.1
(the "Closing") shall take place at the offices of Akin, Gump, Strauss,  Hauer &
Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin,  Texas 78701,
or at such  other  location  as the  parties  may  agree.  The date on which the
Closing occurs is hereinafter referred to as the "Closing Date." -------

         1.3 Assets.  The term "Assets"  shall mean the items listed on Schedule
1.3 attached hereto, all Permits (as hereinafter defined),  all business records
of Refractive Surgery (as hereinafter  defined) and the Business (as hereinafter
defined),  all contract rights of BDEC under leases (including rights to receive
returns of deposits  under such leases) or contracts  listed on Schedule 1.3 and
all of the business and goodwill of Refractive Surgery and the Business. Each of
the Sellers  hereby  represents  and warrants that the Assets include all of the
equipment, instruments, computer software used in connection with the equipment,
Permits, personal property, furniture, business records and other assets of BDEC
that are used  primarily  in or are  materially  relied  on for the  conduct  of
Refractive Surgery and the Business, except for those items that are part of the
ambulatory surgery center. As used in this Agreement, "Refractive Surgery" shall
mean,  collectively,  any current and/or future surgical  procedures intended to
correct myopia,  hyperopia or astigmatism of the eye, excluding procedures aimed
only at  restoring  accommodation  (presbyopia)  and  procedures  to treat  only
cataracts, glaucoma,  oculoplastics or retinal abnormality.  Notwithstanding the
foregoing, the following shall not be "Assets" and shall be retained by BDEC:

     (a) all activities that constitute the practice of medicine;

     (b) the books of account and record  books of BDEC  (complete  and accurate
copies of which,  insofar as they  relate to the  Business  during the  calendar
years 1997,  1998 and 1999,  shall be provided to Prime on or before the Closing
Date);

     (c) BDEC's rights under this Agreement;

     (d) assets that are neither used  primarily  in, nor  materially  relied on
for, the conduct of Refractive Surgery;

     (e) that single certain laser  currently  being leased to a physician group
in Memphis,  Tennessee,  and any interest existing on the Closing Date that BDEC
may have in the current or future profits of the facility  utilizing such laser;
and
     (f) BDEC's ownership interest in Newco II.

         1.4 Assumed Liabilities. At the Closing, Newco II shall only assume, as
of the Effective Time, lease or contract obligations of BDEC arising under lease
agreements  assigned to Newco II  pursuant to Section 1.3 and those  liabilities
set forth on Schedule 1.4 by item and amount.  Such limited  assumption shall be
pursuant to that certain general  conveyance,  assignment and transfer of assets
and  assumption  of  lease  obligations,  attached  hereto  as  Exhibit  D  (the
"Assignment and Assumption Agreemen ) to be executed by Newco II, Prime and BDEC
at the Closing, effective as of the Effective Time. With respect to any lease or
other contract obligations reflected on Schedule 1.3 and assumed by Newco II, it
is agreed  that  Newco II will only be  assuming  obligations  thereunder  which
accrue after the Effective Time, and will have no responsibility  whatsoever for
any breaches or defaults which occurred prior to the later of the Effective Time
or the Closing Date, or for  obligations  accruing prior to the Effective  Time.
Except for those  liabilities  and contract and lease  obligations  specifically
assumed  by Newco II as  provided  above,  any and all debts,  liabilities,  and
obligations of BDEC, whether known or unknown, absolute, contingent or otherwise
(including,  but not limited to,  federal,  state,  and local  taxes,  any sales
taxes,  use taxes and property  taxes,  any taxes arising from the  transactions
contemplated by this Agreement and any  liabilities  arising from any litigation
or civil,  criminal or regulatory proceeding involving or related to BDEC or its
business)  shall remain the sole  responsibility  of BDEC.  Notwithstanding  any
provision  of this  Agreement,  Newco I,  Newco II and Prime do not  assume  any
debts,  obligations  or  liabilities  of  BDEC  whatsoever,   except  for  those
liabilities and contract and lease  obligations  described in the first sentence
of this Section.

     1.5  Payment  of  Purchase  Price.  The  Purchase  Price  shall  be paid in
immediately available funds at the Closing. -------------------------

                                  ARTICLE II t"

               Representations and Warranties of Prime and PMSI t"

         Prime and PMSI each, jointly and severally,  represents and warrants to
BDEC, LASIK, Dulaney, Barnet and Rosenberg that each of the following matters is
true and correct in all respects as of the Closing (with the understanding  that
BDEC,  LASIK,  Dulaney,  Barnet and  Rosenberg  are relying  materially  on such
representations and warranties in entering into and performing this Agreement):

         2.1  Due  Organization  and  Principal  Executive  Office.  PMSI  is  a
corporation duly organized, validly existing and in good standing under the laws
of the State of Delaware and has full corporate  power and authority to carry on
its  business  as now  conducted  and as proposed  to be  conducted.  Prime is a
corporation  duly organized,  validly  existing,  and in good standing under the
laws of the State of Delaware  and has full  corporate  power and  authority  to
carry on its business as now conducted and as proposed to be conducted. Prime is
a wholly-owned  subsidiary of PMSI. The principal  executive offices of PMSI and
Prime are located at 1301 Capital of Texas  Highway,  Austin,  Texas  78746.  No
other person or entity has any right to acquire any ownership interest in Prime.
Complete and accurate copies of the Articles of Incorporation,  Bylaws,  and all
amendments thereto,  of PMSI and of Prime, have been delivered to Sellers.  PMSI
and Prime are  qualified to do business  and are in good  standing in each state
where  such  qualification  is  required  for the  conduct  of its  business  as
conducted on the Closing Date.

         2.2 Due  Authorization.  PMSI  and  Prime  each  have  full  power  and
authority to enter into and perform this Agreement and each Transaction Document
(as hereinafter  defined) required to be executed by it in connection  herewith.
The execution,  delivery, and performance of this Agreement and such Transaction
Documents have been duly authorized by all necessary  action of PMSI,  Prime and
their respective  directors and  shareholders.  This Agreement has been duly and
validly  executed and  delivered by PMSI and Prime and  constitutes  a valid and
binding obligation of each enforceable  against it in accordance with its terms.
The execution, delivery, and performance of this Agreement, and each Transaction
Document  required  herein to be  executed by PMSI or Prime does not (a) violate
any federal,  state, county, or local law, rule, or regulation  applicable to it
or its business (with the understanding  and agreement that this  representation
does not apply to matters  relating to the operation of Newco II or the Business
on and  after the  Closing),  (b)  violate  or  conflict  with,  or  permit  the
cancellation  of, any  agreement  to which it is a party,  or by which it or its
properties are bound, or result in the creation of any lien,  security interest,
charge, or encumbrance upon any of such properties,  (c) permit the acceleration
of the  maturity  of any  indebtedness  of, or any  indebtedness  secured by the
property of, PMSI or Prime, or (d) violate or conflict with any provision of the
Articles of Incorporation  or Bylaws of either.  No action,  consent,  waiver or
approval of, or filing with, any federal,  state,  county or local  governmental
authority  is  required  by PMSI or Prime  in  connection  with  the  execution,
delivery, or performance of this Agreement (or any Transaction Document).

         2.3  Financial  Statements.   The  audited  balance  sheet  and  income
statement  for PMSI as of and for each of the years ended  December 31, 1997 and
1998, and the unaudited  balance sheets and income statements for PMSI as of and
for the six (6) months ended June 30, 1999  (collectively,  the "PMSI  Financial
Statements")  are attached  hereto as Exhibit E. The PMSI  Financial  Statements
have been prepared in accordance with generally accepted  accounting  principles
consistently  applied  ("GAAP")  (except  as  specifically  noted  therein or in
Schedule  2.3)  and  fairly  present  the  financial  position  and  results  of
operations  of PMSI, as of the  indicated  dates and for the indicated  periods.
Except as disclosed in Schedule  2.3 and except to the extent  specifically  and
fully reflected in the PMSI Financial Statements  (including the notes thereto),
PMSI does not have any  liabilities  of a type that would be required by GAAP to
be  reflected  as such in the PMSI  Financial  Statements  (including  the notes
thereto) other than current liabilities on open account incurred in the ordinary
course  of  business  consistent  with  past  practices.  Except as set forth in
Schedule  2.3 hereto,  since June 30,  1999 there has been no  material  adverse
change in the financial position, assets or results of operations of PMSI.

         2.4  Permits,  etc.  To the best of PMSI's  knowledge,  PMSI,  and each
subsidiary  or other entity for which  greater than fifty  percent  (50%) of the
outstanding  voting  equity  interests  are  controlled  by  PMSI,  directly  or
indirectly  (collectively,  the "PMSI Controlled Parties"),  has complied in all
material respects, and is in compliance in all material respects, with the terms
and  conditions  of all  issued or pending  federal,  state,  county,  and local
governmental  licenses,  certificates,  certificates of need, permits,  waivers,
filings and orders  (collectively,  "Permits")  held or applied for by it in the
conduct of its business.  To PMSI's knowledge,  no additional Permit is required
from any federal, state, county, or local governmental agency or body thereof in
connection  with  the  conduct  of the  business  (as  such  business  has  been
conducted) of PMSI or any PMSI  Controlled  Party. No claim has been made by any
governmental  authority  (and,  to the knowledge of PMSI, no such claim has been
threatened)  to the  effect  that a  Permit  not  possessed  by PMSI or any PMSI
Controlled  Party is  necessary  in respect of the business of PMSI or such PMSI
Controlled Party.

         2.5      Environmental Issues.

          (a) For purposes of this Section,  the term "environmental laws" shall
     mean all laws and  regulations  relating  to the  manufacture,  processing,
     distribution, use, treatment, storage, disposal, transport, or handling, or
     the  emission,  discharge,  or  release,  of  any  pollutant,  contaminant,
     chemical,  or  industrial  toxic or hazardous  substance or waste,  and any
     order related thereto.

          (b) PMSI, and each PMSI Controlled Party, has complied in all material
     respects with and obtained all authorizations and made all filings required
     by all environmental laws applicable to its business.

                  (c) Neither  PMSI nor any PMSI  Controlled  Party has received
any notice from the United States  Environmental  Protection Agency that it is a
potentially  responsible party under the Comprehensive  Environmental  Response,
Compensation  and  Liability  Act  ("Superfund  Notice"),  any citation from any
federal,  state or local  governmental  authority  for  non-compliance  with its
requirements  with  respect to air,  water or  environmental  pollution,  or the
improper storage,  use or discharge of any hazardous waste, other waste or other
substance  or other  material  ("Citations")  pertaining  to its business or any
written  notice from any private  party  alleging any such  non-compliance;  and
there are no pending  or  unresolved  Superfund  Notices,  Citations  or written
notices from private parties alleging any such non-compliance.

         2.6 Claims and  Proceedings.  Attached hereto as Schedule 2.6 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending  against  PMSI or any PMSI  Controlled  Party,  at law or in equity,  or
before or by any court, municipal or other governmental department,  commission,
board, agency, or instrumentality.  Except as set forth on Schedule 2.6 attached
hereto, none of such claims, actions, suits, proceedings, or investigations will
result in any  liability  or loss to PMSI or such PMSI  Controlled  Party  which
(individually  or in the  aggregate) is material,  and neither PMSI nor any PMSI
Controlled  Party has been, or is now, subject to any order,  judgment,  decree,
stipulation,  or consent of any court, governmental body, or agency. No inquiry,
action, or proceeding has been asserted, instituted or threatened against either
PMSI or Prime to restrain  or  prohibit  the  carrying  out of the  transactions
contemplated by this Agreement or to challenge the validity of such transactions
or any part thereof or seeking damages on account thereof.

         2.7 Taxes. All federal, foreign, state, county, and local income, gross
receipts,  excise, property,  franchise,  license, sales, use, withholding,  and
other  tax  (collectively,   "Taxes")  returns,  reports,  and  declarations  of
estimated tax (collectively,  "Returns") which were required to be filed by PMSI
or any PMSI Controlled Party on or before the date hereof have been filed within
the time  (including any applicable  extensions)  and in the manner  provided by
law,  and all such  Returns are true and correct in all  material  respects  and
accurately  reflect the Tax liabilities of PMSI or such PMSI  Controlled  Party.
All Taxes,  assessments,  penalties,  and interest which have become due by PMSI
pursuant  to such  Returns  have been  paid or  adequately  accrued  in the PMSI
Financial  Statements.  The provisions for Taxes  reflected on the balance sheet
contained in the PMSI  Financial  Statements are adequate to cover all of PMSI's
estimated Tax  liabilities  for the respective  periods then ended and all prior
periods.  As of the  Closing  Date,  PMSI will not owe any Taxes for any  period
prior to the Closing which are not reflected on the PMSI  Financial  Statements,
except for Taxes  attributable to the operations of PMSI between the date of the
PMSI  Financial  Statements  and the Closing  Date.  PMSI has not  executed  any
presently  effective  waiver or extension of any statute of limitations  against
assessments and collection of Taxes.  There are no pending or threatened claims,
assessments,   notices,   proposals   to   assess,   deficiencies,   or   audits
(collectively,  "Tax Actions")  against PMSI or any PMSI  Controlled  Party with
respect  to any Taxes owed or  allegedly  owed by such  party.  There are no tax
liens on any of the  assets of PMSI or any PMSI  Controlled  Party.  Proper  and
accurate  amounts  have  been  withheld  and  remitted  by PMSI  and  each  PMSI
Controlled Party from and in respect of all persons from whom either is required
by  applicable  law to  withhold  for all  periods  in  compliance  with the tax
withholding  provisions of all applicable  laws and  regulations.  PMSI is not a
party to any tax sharing agreement.

         2.8  Certain  Consents.  Except as set forth on Schedule  2.8  attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by PMSI or Prime from third  parties  in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments and agreements to be executed and delivered at
the Closing,  including,  without  limitation,  those set forth in, or delivered
pursuant to, ARTICLE V hereof and the Target Center Loan Documents (all of which
are collectively referred to as the "Transaction Documents").

     2.9 Brokers. Neither PMSI nor Prime has engaged, or caused any liability to
be incurred to, any finder,  broker,  or sales agent (or has paid,  or will pay,
any finders fee or similar fee or commission  to any person) in connection  with
the execution,  delivery,  or performance of this Agreement or the  transactions
contemplated  hereby.  -------  2.10  Interest in  Competitors,  Suppliers,  and
Customers.  Except as set forth on Schedule

     2.10 attached  hereto,  neither PMSI nor any PMSI Controlled  Party, and to
the  knowledge  of PMSI no  officer,  director  or  employee of PMSI or any PMSI
Controlled Party, has any ownership interest (other than ownership of securities
of a publicly  held  corporation  or other  entity  constituting  less than five
percent  (5%)  of that  class  of  outstanding  securities)  in any  competitor,
customer or  supplier  of the  -------------------------------------------------
- ------------- Refractive Surgery business.

     2.11 Warranties.  Except as set forth on Schedule 2.11 attached hereto,  no
claims for breach of product or service  warranties  have been made against PMSI
or any PMSI Controlled Party since January 1, 1996. ---------- -------------

     2.12 No Defaults.  Neither PMSI nor Prime is aware of any breach or default
by the other of any of the representations,  warranties, covenants or agreements
contained herein. -----------

         2.13     Investment Representations.  Each of PMSI and Prime:

     (a) Is an "accredited investor," and has not retained or consulted with any
"purchaser  representative" (as such terms are defined in Rule 501 of Regulation
D promulgated  under the  Securities  Act of 1933,  as amended (the  "Securities
Act")) in connection  with its execution of this Agreement and the  consummation
of the transactions contemplated hereby;

     (b) Has such  knowledge and  experience  in financial and business  matters
that it is capable of evaluating  the merits and risks of an investment in Newco
I and Newco II;

                  (c) Will acquire any Newco I or Newco II interests for its own
account for investment and not with the view toward resale or  redistribution in
a manner which would require  registration  under the Securities  Act, the Texas
Securities Act, as amended,  or the securities laws of any other state,  and has
no reason to  anticipate  any change in its  circumstances  or other  particular
occasion  or  event  which  would  cause  it to sell  its  Newco I or  Newco  II
interests, or any part thereof or interest therein, and has no present intention
of  dividing  the Newco I and Newco II  interests  with others or  reselling  or
otherwise disposing of the Newco I and Newco II interests or any part thereof or
interest   therein  either  currently  or  after  the  passage  of  a  fixed  or
determinable  amount  of time or upon the  occurrence  or  nonoccurrence  of any
predetermined event or circumstance;

                  (d) In connection  with  entering into this  Agreement and the
Transaction  Documents  to which each is a party,  and in making the  investment
decisions  associated  therewith,   has  neither  received  nor  relied  on  any
representations or warranties from Newco I, Newco II, Sellers, the affiliates of
the foregoing or the officers,  directors,  shareholders,  employees,  partners,
members, agents,  consultants,  personnel or similarly related parties of any of
the foregoing, other than those representations and warranties contained in this
Agreement;

     (e) Is able to bear the economic  risk of an  investment in the Newco I and
Newco II  interests  and it has  sufficient  net worth to  sustain a loss of its
entire  investment  without  material  economic  hardship  if such a loss should
occur; and

     (f)  Acknowledges  that the  Newco I and Newco II  interests  have not been
registered under the Securities Act, or the securities laws of any of the states
of the United  States,  that an investment in the Newco I and Newco II interests
involves a high degree of risk,  and that the Newco I and Newco II interests are
an illiquid investment.
                                                   ARTICLE III "

 Representations and Warranties of BDEC, LASIK, Dulaney, Barnet and Rosenberg "

     Each of BDEC and  LASIK,  jointly  and  severally,  hereby  represents  and
warrants  to Prime  and PMSI  that  each of the  following  matters  is true and
correct in all respects.  With respect to representations  and warranties by the
Sellers,  each of Dulaney,  Barnet and  Rosenberg,  severally,  and not jointly,
hereby makes such  representations  or warranties  only about or with respect to
himself.  Each  representation  and warranty  contained  in this  ARTICLE  shall
survive the Closing and shall be deemed made as of both the Closing Date and the
Effective  Time  (with  the  understanding  that  Prime  and  PMSI  are  relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement).

         3.1 Due Organization. BDEC is an Arizona professional limited liability
company,  and LASIK is a Delaware limited  liability  company.  Each of BDEC and
LASIK is duly organized,  validly existing,  and in good standing under the laws
of its state of formation, and each has full power and authority to carry on its
business as now  conducted  and as proposed to be  conducted.  Dulaney,  Barnet,
Scott A. Perkins, M.D. ("Perkins"),  and Robert B. Pinkert, O.D. ("Pinkert") are
the only  members  of BDEC,  and each  owns  that  percentage  of BDEC set forth
opposite his name on Schedule 3.1(a). Dulaney,  Barnet,  Rosenberg,  Perkins and
Pinkert are the only members of LASIK,  and each owns that  percentage  of LASIK
set  forth  opposite  his  name on  Schedule  3.1(a).  Immediately  prior to the
Closing,  BDEC is the  sole,  one  hundred  percent  (100%)  owner of all of the
outstanding  ownership interests in Newco II, and LASIK is the sole, one hundred
percent (100%) owner of all of the outstanding  ownership  interests in Newco I.
Except as expressly provided in this Agreement, as of the Closing Date, no other
person or entity  has any right to acquire  any  ownership  interest  in BDEC or
LASIK.  As of the  Closing  Date,  there is only one  class  or  designation  of
membership  interests in each of BDEC and LASIK.  Complete and correct copies of
the organizational documents, and all amendments thereto, of BDEC and LASIK have
been  delivered  to  Prime.  BDEC is  qualified  to do  business  and is in good
standing  in the states set forth on  Schedule  3.1(b)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of BDEC's business as conducted on the Closing Date.

     3.2  Subsidiaries.  Except as set forth on Schedule  3.2,  neither BDEC nor
LASIK  directly or  indirectly  has (or possesses any options or other rights to
acquire) any subsidiaries or any direct or indirect  ownership  interests in any
person,   business,   corporation,   partnership,   limited  liability  company,
association, joint venture, trust, or other entity. ------------ ------------

         3.3 Due  Authorization.  Each  Seller has full power and  authority  to
enter  into and  perform  this  Agreement  and each other  Transaction  Document
required to be executed by such Seller in connection  herewith.  The  execution,
delivery,  and performance of this Agreement and such Transaction Documents have
been duly authorized by all necessary  action of BDEC,  LASIK,  and all of their
respective  managers  and  members.  This  Agreement  has been duly and  validly
executed  and  delivered  by the  Sellers  and  constitutes  a valid and binding
obligation of the Sellers enforceable against them in accordance with its terms.
The  execution,  delivery,  and  performance of this  Agreement,  and each other
Transaction  Document required herein to be executed by the Sellers does not (a)
violate any federal, state, county, or local law, rule, or regulation applicable
to the Sellers,  the Sellers' business or the Assets (with the understanding and
agreement  that this  representation  does not apply to matters  relating to the
operation of Newco II or the Business on and after the Closing),  (b) violate or
conflict with, or permit the  cancellation of, any agreement to which any of the
Sellers is a party,  or by which any  Seller or its  properties  are  bound,  or
result in the creation of any lien,  security  interest,  charge, or encumbrance
upon any of such properties,  (c) permit the acceleration of the maturity of any
indebtedness  of, or any  indebtedness  secured by the property of, BDEC, or (d)
violate or conflict with any provision of the organizational documents of either
BDEC or LASIK.  No action,  consent,  waiver or approval of, or filing with, any
federal, state, county or local governmental authority is required by any of the
Sellers in connection  with the  execution,  delivery,  or  performance  of this
Agreement (or any Transaction Document).


         3.4  Financial  Statements.  The  unaudited  income  statement  for the
Business  for  the  six  months  ended  June  30,  1999  (the  "BDEC   Financial
Statements") is attached hereto as Exhibit F. The BDEC Financial Statements have
been  prepared  on the accrual  basis of  accounting  and fairly and  accurately
represent  the results of  operations of the Business for such six month period.
Except as set forth in Schedule 3.4 hereto,  since June 30, 1999, there has been
no  material  adverse  change in the  financial  position,  assets or results of
operations of the Business.  For each of the calendar  years 1997 and 1998,  and
for the six months  ended June 30, 1999,  Exhibit F also  contains a list of the
total number of Refractive  Surgery  procedures  performed by BDEC,  and related
charges, adjustments, collections and procedures, during the respective periods,
including  subtotals  reflecting  the numbers of each type of  procedure,  and a
separate listing of the percentage of procedures done at any location other than
at  4800  North  22nd  Street,  Phoenix,  Arizona  85016.  Each  of the  Sellers
represents and warrants that Exhibit F fairly represents the number and location
of  Refractive  Surgery  procedures  performed  by BDEC,  and  related  charges,
adjustments, collections and procedures, for the indicated periods.


         3.5  Conduct  of  Business;  Certain  Actions.  Except  as set forth on
Schedule  3.5  attached  hereto,  since June 30, 1999,  BDEC has  conducted  the
Business and  operations of the Business in the ordinary  course and  consistent
with its past  practices and has not,  with respect to or in a manner  affecting
the Business (a) purchased,  retired,  or redeemed any membership  interest from
any Seller,  (b) increased the  compensation  of any of the  employees,  agents,
contractors, vendors or other parties, except for wage and salary increases made
in the ordinary  course of business and  consistent  with the past  practices of
BDEC, (c) made capital expenditures exceeding $10,000 individually or $25,000 in
the  aggregate,  (d) sold any  asset  (or any group of  related  assets)  in any
transaction (or series of related  transactions)  in which the purchase price or
book value for such asset (or group of related  assets)  exceeded  $10,000,  (e)
discharged  or  satisfied  any lien or  encumbrance  or paid any  obligation  or
liability,  absolute or contingent,  other than current liabilities incurred and
paid in the ordinary  course of business,  (f) made or  guaranteed  any loans or
advances to any party whatsoever,  (g) suffered or permitted any lien,  security
interest,  claim, charge, or other encumbrance to arise or be granted or created
against or upon any of its assets, real or personal, tangible or intangible, (h)
canceled,  waived,  or released any of BDEC's debts,  rights,  or claims against
third  parties,  (i) made any  change  in its  method of  accounting,  (j) made,
entered into, amended, or terminated any written employment  contract,  created,
made,  amended,  or terminated  any bonus,  stock option,  pension,  retirement,
profit sharing, or other employee benefit plan or arrangement, or withdrawn from
any  "multi-employer  plan" (as defined in the Internal Revenue Code of 1986, as
amended (the "Code")) so as to create any liability  under ERISA (as hereinafter
defined) to any person or entity,  (k)  amended,  terminated  or  experienced  a
termination of any material contract, agreement, lease, franchise, or license to
which it is a party, (l) entered into any other material  transactions except in
the ordinary  course of business,  (m) entered  into any  contract,  commitment,
agreement,  or understanding  to do any acts described in the foregoing  clauses
(a)-(l) of this Section, (n) suffered any material damage,  destruction, or loss
(whether or not covered by insurance) to any assets, (o) experienced any strike,
slowdown,  or demand for recognition by a labor  organization by or with respect
to any of its employees, or (p) experienced or effected any shutdown, slow-down,
or cessation of any operations conducted by, or constituting part of, it.

         Each of LASIK, Newco I and Newco II were formed in contemplation of the
transactions  described in this  Agreement,  and none of them has  conducted any
business since its formation  (except for the authorization of and entering into
this Agreement and the Transaction Documents).

         3.6  Ownership of Assets;  Licenses,  Permits,  etc.  BDEC has good and
marketable  title to, or lessee's  interest in, all of the Assets free and clear
of  all  liens,  security  interests,   claims  and  encumbrances  of  any  kind
whatsoever,  including,  without limitation,  the Assets specifically set out on
Schedule  1.3. The Assets  include all property and assets,  real,  personal and
mixed, tangible and intangible, including leases and other contracts, which are,
on the  Closing  Date,  used  primarily  in, or  materially  relied on for,  the
operation of the Business as then  conducted.  The Assets are in good  operating
condition and repair, subject to ordinary wear and tear, taking into account the
respective  ages of the  properties  involved  and  are,  on the  Closing  Date,
adequate for the conduct of the Business as then  conducted.  Attached hereto as
Schedule  3.6 is a list and  description  of all Permits  held or applied for by
BDEC and used or relied on as of the Closing Date in connection  with the Assets
or the Business. To the best of its knowledge, BDEC has complied in all material
respects, and BDEC is in compliance in all material respects, with the terms and
conditions of any such Permits.  To BDEC's  knowledge,  no additional  Permit is
required from any federal,  state,  county, or local governmental agency or body
thereof in  connection  with the conduct of the Business on the Closing Date. No
claim has been made by any governmental  authority (and, to the knowledge of the
Sellers,  no such claim has been  threatened)  to the  effect  that a Permit not
possessed by BDEC is  necessary in respect of the Business on the Closing  Date.
All of the Permits noted on the attached  Schedule 3.6 are freely assignable to,
or may be acquired by, Prime and Newco II. In the event any such Permits are not
assigned  to Prime or Newco II, BDEC  agrees to fully  cooperate  (at Newco II's
expense)  in any effort by Prime or Newco II to obtain a similar or  replacement
Permit.

         3.7      Environmental Issues.

     (a) For purposes of this Section,  the term "environmental laws" shall mean
all laws and regulations relating to the manufacture,  processing, distribution,
use, treatment,  storage,  disposal,  transport,  or handling,  or the emission,
discharge,  or release, of any pollutant,  contaminant,  chemical, or industrial
toxic or hazardous substance or waste, and any order related thereto,  affecting
the Assets or the Business.

     (b) BDEC has  complied  in all  material  respects  with and  obtained  all
authorizations   and  made  all  filings  required  by  all  environmental  laws
applicable to the Business.  The properties  occupied or used in the Business by
BDEC have not been contaminated with any hazardous wastes, hazardous substances,
or  other   hazardous  or  toxic   materials  in  violation  of  any  applicable
environmental  law, the violation of which could have a material  adverse impact
on the Business.

     (c) BDEC has not received any Superfund Notice, any Citation  pertaining to
its  business or any written  notice from any private  party  alleging  any such
non-compliance;  and there  are no  pending  or  unresolved  Superfund  Notices,
Citations  or  written   notices  from   private   parties   alleging  any  such
non-compliance.

     3.8 Intellectual Property Rights. There are no patents,  trademarks,  trade
names,  or  copyrights  used or relied on in the Business,  and no  applications
therefor,  owned by or  registered  in the name of BDEC or in which BDEC has any
right, license, or interest.  With respect to the Business,  BDEC is not a party
to any license  agreement,  either as licensor or licensee,  with respect to any
patents, trademarks, trade names, or copyrights. Except as set forth on Schedule
3.13, with respect to the  ----------------------------  ------------- Business,
BDEC has not received any notice that it is  infringing  any patent,  trademark,
trade name, or copyright of others.

     3.9 Compliance with Laws.  With respect to the Assets and the Business,  to
its  knowledge,  BDEC has  complied  in all  material  respects,  and BDEC is in
compliance in all material respects,  with all federal, state, county, and local
laws,  rules,  regulations  and  ordinances  currently  in effect.  BDEC has not
received any notice that a claim has been made or threatened by any governmental
authority  against BDEC to the effect that the  Business  fails to comply in any
respect with any law, rule, -------------------- regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held in relation to or  applicable  to the  Business at any time
within the past three (3) years,  which  schedule  sets forth in respect of each
such policy the policy name,  policy number,  carrier,  term,  type of coverage,
deductible  amount or self-insured  retention  amount,  limits of coverage,  and
annual premium.  To the knowledge of Sellers,  no event directly relating to the
Business has occurred  which will result in a retroactive  upward  adjustment of
premiums under any such policies or which is likely to result in any prospective
upward adjustment in such premiums.  Except as described on Schedule 3.10, there
have been no material  changes in the type of insurance  coverage  maintained by
BDEC for the  Business  during  the past  three  (3)  years,  including  without
limitation  any change which has resulted in any period during which BDEC had no
insurance coverage with respect to the Business. Except as described on Schedule
3.10,  excluding  insurance  policies which have expired and been  replaced,  no
insurance  policy of BDEC related to the Business has been  canceled  within the
last three (3) years and no threat  has been made to cancel  any such  insurance
policy of BDEC within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
BDEC does not maintain nor does it  contribute  nor is it required to contribute
to any  "employee  welfare  benefit  plan" (as  defined in  section  3(1) of the
Employee  Retirement  Income  Security Act of 1974 (and any sections of the Code
amended by it) and all regulations promulgated thereunder, as the same have from
time to time been amended  ("ERISA")) or any "employee pension benefit plan" (as
defined in ERISA). Except as described on Schedule 3.11, BDEC does not presently
maintain  and has  never  maintained,  or had any  obligation  of any  nature to
contribute to, a "defined benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all  confidentiality  agreements) that relate to or affect the Assets or the
Business, to which BDEC is a party or by which BDEC or its properties are bound,
pursuant to which the  obligations  thereunder  of any party thereto are, or are
contemplated as being, in respect of any such individual contracts, commitments,
leases, or other agreements during any year during the term thereof,  $25,000 or
greater,  or which are  otherwise  material to the  Business  (collectively  the
"Contracts"  and  individually,  a  "Contract").  BDEC is not  and,  to the best
knowledge  of Sellers,  no other party  thereto is in default  (and no event has
occurred which, with the passage of time or the giving of notice, or both, would
constitute a default by BDEC or, to the best knowledge of Sellers,  by any other
party thereto) under any Contract.  BDEC has not waived any material right under
any Contract, and no consents or approvals (other than those obtained in writing
and  delivered  to Prime prior to Closing)  are  required  under any Contract in
connection with the sale of the Assets or the  consummation of the  transactions
contemplated hereby.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or threatened in writing against BDEC, at law or in equity, or before or
by any court,  municipal or other governmental  department,  commission,  board,
agency,  or  instrumentality,  which  relate to or affect  the  Business  or the
Assets.  Except as set forth on  Schedule  3.13  attached  hereto,  none of such
claims,  actions,  suits,  proceedings,  or  investigations  will  result in any
liability or loss to BDEC which  (individually or in the aggregate) is material,
and BDEC has not been,  and BDEC is not now,  subject  to any  order,  judgment,
decree,  stipulation,  or consent of any court, governmental body, or agency. No
inquiry,  action,  or proceeding  has been asserted,  instituted,  or threatened
against  BDEC to restrain  or  prohibit  the  carrying  out of the  transactions
contemplated by this Agreement or to challenge the validity of such transactions
or any part thereof or seeking damages on account thereof.

         3.14 Taxes.  All Returns  which were required to be filed by BDEC on or
before the date hereof have been filed within the time (including any applicable
extensions) and in the manner provided by law, and all such Returns are true and
correct in all material  respects and accurately  reflect the Tax liabilities of
BDEC.  All Taxes,  assessments,  penalties,  and interest  which have become due
pursuant  to such  Returns  have been  paid or  adequately  accrued  in the BDEC
Financial  Statements.  The provisions for Taxes  reflected on the balance sheet
contained in the BDEC  Financial  Statements are adequate to cover all of BDEC's
estimated Tax  liabilities  for the respective  periods then ended and all prior
periods;  provided,  however,  that BDEC is not  required to pay federal  income
taxes  and,  accordingly,  has not made  any  allowance  in the  BDEC  Financial
Statements for any federal income taxes.  As of the Closing Date,  BDEC will not
owe any Taxes for any period prior to the Closing which are not reflected on the
BDEC Financial  Statements,  except for Taxes  attributable to the operations of
BDEC between the date of the BDEC  Financial  Statements  and the Closing  Date.
BDEC has not executed any presently effective waiver or extension of any statute
of limitations against assessments and collection of Taxes. There are no pending
or  threatened  Tax  Actions  against  BDEC with  respect  to any Taxes  owed or
allegedly  owed by BDEC.  There are no tax  liens on any of the  assets of BDEC.
Proper and accurate  amounts have been withheld and remitted by BDEC from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable  laws  and  regulations.  BDEC  is not a  party  to any  tax  sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of those  individuals (the "Employees") who
will be involved in the  operation  of the  Business  after the  Effective  Time
pursuant to the Collocation  Agreement (as hereinafter  defined).  Except as set
forth  on  Schedule  3.15,  there  are  no  bonus,  profit  sharing,  percentage
compensation,  company automobile,  club membership, and other like benefits, if
any, paid or payable by BDEC to any Employees from December 31, 1998 through the
Closing Date. Schedule 3.15 attached hereto also contains a brief description of
all material terms of employment agreements and confidentiality  agreements with
respect  to the  Business  to which BDEC is a party and all  severance  benefits
which any  Employee or sales  representative  involved in the  operation  of the
Business is or may be entitled to receive.  BDEC has delivered to Prime accurate
and  complete  copies  of  all  such  employment   agreements,   confidentiality
agreements, and all other agreements, plans, and other instruments to which BDEC
is a party and under which any Employees are entitled to receive benefits of any
nature.  The  employee  relations  of BDEC are good and there is no  pending  or
threatened (i) union organization campaign relating to BDEC, (ii) claims against
BDEC  or the  Sellers  by any  Employees  (other  than  those  certain  Workers'
Compensation claims specifically described on Schedule 3.13), or (iii) presently
anticipated terminations,  resignations or retirements of any Employees. None of
the Employees are  represented by any labor union or  organization.  There is no
unfair labor  practice  claim against BDEC before the National  Labor  Relations
Board or any strike, labor dispute,  work slowdown,  or work stoppage pending or
threatened against or involving BDEC.

         3.16 Business Relations. Sellers have no reason to believe and have not
been  notified  that any supplier or customer of BDEC will cease or refuse to do
business with BDEC or Newco II in the same manner as previously  conducted  with
BDEC as a  result  of or  within  one (1) year  after  the  consummation  of the
transactions  contemplated hereby, to the extent such cessation or refusal might
affect  the  Assets or the  Business.  BDEC has not  received  any notice of any
disruption  (including  delayed  deliveries or  allocations by suppliers) in the
availability of the materials or products used by BDEC.

     3.17 Agents. Except as set forth on Schedule 3.17 attached hereto, BDEC has
not  designated or appointed any person (other than BDEC's  employees,  officers
and managers) or other entity to act for it or on its behalf with respect to the
Business  pursuant to any power of attorney or any agency  which is presently in
effect. ------ -------------

     3.18  Commission  Sales  Contracts.  Except as disclosed  in Schedule  3.18
attached hereto,  BDEC does not employ or have any  relationship,  related to or
arising out of the Assets or the  Business,  with any  individual,  corporation,
partnership, or other entity whose compensation from BDEC is in whole or in part
determined on a commission basis. -------------------------- -------------

     3.19  Certain  Consents.  Except as set  forth on  Schedule  3.19  attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by  any  Sellers  from  third  parties   (including,   without
limitation,  Perkins,  Pinkert,  or the spouses of Dulaney,  Barnet,  Perkins or
Pinkert) in connection  with the execution,  delivery,  and  performance of this
Agreement or any other Transaction Document. ---------------- -------------

     3.20 Brokers. No Seller has engaged, or caused any liability to be incurred
to, any finder,  broker,  or sales agent (or has paid,  or will pay, any finders
fee or  similar  fee or  commission  to  any  person)  in  connection  with  the
execution,  delivery,  or  performance  of this  Agreement  or the  transactions
contemplated hereby. -------

         3.21 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on  Schedule  3.21  attached  hereto,  no Seller or any  affiliate  of any
Seller, and to the knowledge of Sellers no officer,  manager or employee of BDEC
or any affiliate of any officer,  manager or employee of BDEC, has any ownership
interest in any competitor, customer or supplier of the Business or any property
used in the  operation of the Business.  For purposes of this  Section,  none of
Barnet,  Dulaney,  Perkins or Pinkert,  shall be  considered,  in his individual
capacity, a competitor, customer, or supplier of the Business.

     3.22  Warranties.  Except as set forth on Schedule 3.22,  BDEC has not made
any  warranties or guarantees to third parties with respect to any products sold
or services rendered by it related to the Assets or the Business.  Except as set
forth on  Schedule  3.22  attached  hereto,  no claims  for breach of product or
service  warranties related to the Assets or the Business have been made against
BDEC since January 1, 1996. ---------- ------------- -------------

         3.23     Investment Representations.  Each Seller:

     (a) Is an "accredited investor," and has not retained or consulted with any
"purchaser  representative" (as such terms are defined in Rule 501 of Regulation
D promulgated  under the  Securities  Act of 1933,  as amended (the  "Securities
Act")) in connection  with its execution of this Agreement and the  consummation
of the transactions contemplated hereby;

     (b) Has such  knowledge and  experience  in financial and business  matters
that it is capable of evaluating  the merits and risks of an investment in Newco
I and/or Newco II;

                  (c) Will acquire any Newco I and/or Newco II interests for its
own account for investment and not with the view toward resale or redistribution
in a manner which would require registration under the Securities Act, the Texas
Securities  Act, as amended,  or the  securities  laws of any other  state,  and
Sellers  do not  presently  have any  reason to  anticipate  any change in their
respective circumstances or other particular occasion or event which would cause
such Seller to sell its Newco I and/or Newco II  interests,  or any part thereof
or interest therein, and Sellers have no present intention of dividing the Newco
I and/or Newco II interests  with others or reselling or otherwise  disposing of
the Newco I and/or Newco II  interests  or any part thereof or interest  therein
either currently or after the passage of a fixed or determinable  amount of time
or  upon  the  occurrence  or  nonoccurrence  of  any  predetermined   event  or
circumstance;

                  (d) In connection  with  entering into this  Agreement and the
Transaction  Documents  to which  each  Seller  is a party,  and in  making  the
investment  decisions  associated  therewith,  Sellers have neither received nor
relied on any representations or warranties from Newco I, Newco II, Prime, PMSI,
the  affiliates  of the  foregoing  or the  officers,  directors,  shareholders,
employees,  partners,  managers,  members,  agents,  consultants,  personnel  or
similarly   related   parties  of  any  of  the  foregoing,   other  than  those
representations and warranties contained in this Agreement;

     (e) Is able to bear  the  economic  risk of an  investment  in the  Newco I
and/or Newco II interests and it has  sufficient  net worth to sustain a loss of
its entire  investment  without material economic hardship if such a loss should
occur; and

     (f)  Acknowledges  that the  Newco I and Newco II  interests  have not been
registered under the Securities Act, or the securities laws of any of the states
of the  United  States,  that an  investment  in the  Newco I  and/or  Newco  II
interests  involves  a high  degree  of risk,  and that the Newco I and Newco II
interests are an illiquid investment.
                                                    ARTICLE IV

                                                     Covenants

     4.1  Cooperation  Relating  to  Financial  Statements.   Sellers  agree  to
cooperate  with Prime in the  preparation  of any financial  statements of BDEC,
LASIK,  Newco I and/or Newco II which Prime or its affiliates may be required by
any applicable law to prepare. --------------------------------------------

         4.2 Member and Manager Action. Sellers each agree that, until such time
as none of the Sellers  owns any  ownership  interest in either Newco I or Newco
II, none of them will, without obtaining the prior written consent of Prime, (i)
authorize  the issuance of any  additional  membership  interest in LASIK to any
third  party,  (ii)  cause or allow any  additional  managers  to be  elected as
managers  of  BDEC  or  LASIK,  or  (iii)  unless  allowed  under  the  Transfer
Restriction Agreement (as hereinafter defined),  assign, or otherwise dispose of
any  membership  interest  of LASIK  owned or  controlled  by such  Seller.  The
provisions  of this Section  shall not be construed in a manner which limits the
application of effect of the provisions of Section 8.4(c) of this Agreement.

         4.3      Credit Facilities.

                  (a)  Working  Capital  Line of Credit.  Prime and Newco I each
agree to  execute,  on or before  the  Closing  Date (i) the Loan  Agreement  in
substantially  the form  attached  hereto as Exhibit G1 (the "Loan  Agreement"),
which  provides  for,  among other  credit  accommodations  described  below,  a
revolving  line of credit  in the  maximum  principal  amount  of  $200,000  and
maturing one (1) year after the Closing (the "Working  Capital Line"),  pursuant
to which Newco I shall be entitled,  subject to the conditions  and  limitations
contained in the Loan Agreement, to borrow, repay and reborrow funds in order to
meet obligations of Newco I arising in the ordinary course of business, (ii) the
Assignment and Security  Agreement in substantially  the form attached hereto as
Exhibit  G4,  and  (iii)  in  connection  with the  Working  Capital  Line,  the
Promissory Note in substantially the form attached hereto as Exhibit G2.

                  (b)  Development  Credit  Facility.  The Loan  Agreement  also
provides  for  a  term  loan  facility,  in  the  maximum  principal  amount  of
$40,000,000  (the  "Development  Facility"),  pursuant to which Newco I shall be
entitled,  subject  to the  conditions  and  limitations  contained  in the Loan
Agreement,  to borrow  funds,  from time to time,  in order to finance up to one
hundred percent (100%) of the purchase price (or development  costs) of a Target
Center (as  hereinafter  defined)  being  acquired  (or  developed)  by Newco I;
provided,  however,  that in no event shall the Development  Facility be used in
instances where Prime, PMSI or one of their affiliates independently acquires or
develops a Target  Center as permitted by Section  8.1. In  connection  with the
Development Facility, Newco I agrees to execute, and all parties hereto agree to
vote their interests in Newco I, if any, and to take such other action as may be
necessary,  to cause any entity  through  which  Newco I acquires  or develops a
Target  Center to execute,  on or before each  closing  date of a Target  Center
acquisition  or  the   commencement  of   development,   a  Promissory  Note  in
substantially  the form  attached  hereto as  Exhibit G5 and an  Assignment  and
Security  Agreement in substantially  the form attached hereto as Exhibit G3. In
addition, if Newco I is to obtain, through development or acquisition,  directly
or  indirectly,  a one hundred  percent  (100%)  interest in such Target Center,
Newco I and all  parties  hereto  shall  cause such  Target  Center to execute a
security agreement, acceptable in form and substance to Prime, granting to Prime
the highest  available  priority  security interest in all of the assets of such
Target Center.

                  (c) Notwithstanding  anything herein to the contrary,  Prime's
obligations  to make each  extension of credit  pursuant to subsection (b) above
are subject  entirely and in all  respects to Prime's  obtaining  prior  written
approval from the bank syndication under its outstanding  borrowing  facilities.
Each  of the  parties  to  this  Agreement  acknowledges  and  agrees  that  the
assignment and security agreements,  and security agreements,  executed pursuant
to this Section will be assignable,  and that Prime intends to make a collateral
assignment for the benefit of one or more of its lenders.  In addition,  each of
the parties to this Agreement agrees to take such action (including voting their
interests  in any  entity)  which may be  necessary  to ensure  the  filing  and
perfection  of  security  interests  required  to be  granted  pursuant  to this
Section.

                  (d) Each of the Sellers  acknowledges  and agrees that none of
Prime,  PMSI or any affiliate of either of them may be required to (i) except as
expressly  set forth in this  ARTICLE IV and in Section  8.2(b)(ii),  extend any
financing,  credit  facilities,  guarantees or other credit  enhancements to any
Seller, Newco I or Newco II or (ii) issue any of its capital stock (or rights to
acquire its capital stock) in connection with the acquisition of a Target Center
(provided, however, that Prime, PMSI or such affiliate may elect, upon obtaining
the  consent  of BDEC,  to  issue  its  capital  stock  in  connection  with the
acquisition  of a Target Center by Newco I or any of its  subsidiaries,  and any
such  issuance  shall be treated for all  purposes as a loan by Prime to Newco I
pursuant to the  Development  Credit  Facility,  in an amount  equal to the fair
market value of the capital stock issued on the date of issuance).

         (e) Each of the Sellers and Newco I acknowledges  and agrees that Newco
I shall not distribute (or allow to be distributed) to its members, with respect
to their respective membership interests,  any cash or other property of Newco I
or its  subsidiaries if, at the time of the proposed  distribution,  any amounts
(whether  principal or interest) are outstanding  under the Credit  Documents or
the Target Center  Lending  Documents (as such terms are  hereinafter  defined).
Furthermore,  each of the  Sellers and Newco I agrees that Newco I shall pay all
available cash flow to Prime in payment of Newco I's outstanding obligations, if
any, under the Working  Capital Line and Development  Facility,  irrespective of
whether such payments  exceed the minimum  required  payments  under the Working
Capital Line and Development Facility.  For purposes of allocating such payments
among any two or more of such  outstanding  obligations,  such payments shall be
allocated  pro rata,  based upon the  respective  balances of such  obligations,
unless (i) a greater  portion of the  payment is  required  to be paid  toward a
given  obligation in order to prevent a default with respect to that  obligation
(but only to the extent  necessary  to prevent  such a default)  or (ii)  eighty
percent  (80%) of the  managers of Newco I elect to allocate  the  payments in a
different manner.

                  Notwithstanding  the  foregoing,  as long as there has been no
default by any Seller  under this  Agreement or any other  Transaction  Document
(excluding,  however,  the  Credit  Documents  and  the  Target  Center  Lending
Documents),  then,  to the  extent  that (but only to the extent  that)  Newco I
possesses the cash flow necessary (in the reasonable discretion of a majority of
its managers) to pay its liabilities in the ordinary course consistent with past
practices,  Newco I agrees to make quarterly estimates of its taxable income for
the current tax year and, if not  prohibited by law,  distribute  quarterly (the
"Quarterly  Distributions")  an amount  that would  cover the  federal and state
income  taxes  required  to be paid by its members  with  respect  such  taxable
income, based on each member's then current  proportionate  interest in Newco I,
assuming  that all members pay income  taxes on Newco I's taxable  earnings at a
rate equal to the highest  effective  individual tax rate in effect from time to
time (the Assumed Tax Rate");  provided,  further,  that Newco I shall determine
its  actual  taxable  income  at the end of  each  taxable  year  and (A) if the
Quarterly  Distributions  in a given year should  have been higher  based on the
amount of actual taxable income for that year,  promptly  distribute the amounts
necessary to eliminate such deficiency or (B) if the Quarterly  Distributions in
a given year should have been lower based on the amount of actual taxable income
for that year,  withhold  dollar for dollar from the first  following  Quarterly
Distribution,  and then against  subsequent  Quarterly  Distributions  in a like
manner, the amounts necessary to eliminate such surplus.

     (f) All of the loan  agreements,  promissory  notes,  guarantees,  security
agreements,  assignment and security agreements and other agreements,  documents
or instruments required to be executed by any party pursuant to this Section are
hereinafter collectively referred to as the "Credit Documents."

         4.4  Capital  Contributions.  The  parties  agree that no party  shall,
except  for the  express  provisions  of  Section  1.1 and  Section  4.3 of this
Agreement or of the  Organizational  Documents,  be required to make any capital
contribution, or extend any credit facility or loans, to either Newco I or Newco
II (or a  subsidiary  of  either)  following  the  Closing,  including,  without
limitation, for purposes of providing working capital;  provided,  however, that
this  sentence  shall not affect any party's  obligations  under ARTICLE VI with
respect to any breach of the  representations  or warranties  made by that party
under this Agreement.

     4.5 Ownership Interest Transfer Restriction  Agreement.  Each of the owners
of LASIK agrees that it, and its spouse (if any),  will execute,  on or prior to
the Closing, an Ownership Interest Transfer Restriction  Agreement applicable to
LASIK,  in  substantially  the form attached  hereto as Exhibit H (the "Transfer
Restriction Agreement"),  that imposes certain limitations and conditions on the
sale, transfer, assignment or other disposition of any interest that is directly
or   indirectly   owned   or   -------------------------------------------------
- --------- controlled by such party in LASIK.

         4.6 ASC Option. BDEC acknowledges that it may, but is not obligated to,
acquire an interest in a certain  Ambulatory  Surgical Center located at 4800 N.
22nd St., Phoenix,  Arizona (the "ASC") from Physicians  Resource Group, Inc. or
its  successors  or  affiliates  ("PRG").  Sellers  agree  that,  upon  any such
acquisition,  directly or  indirectly,  by BDEC or any  affiliate of BDEC or any
Seller (including, without limitation, LASIK), Newco I is hereby granted a right
of first  refusal  (the "ASC  Option"  pursuant  to which  Newco I or one of its
wholly  owned  subsidiaries  may,  in  its  sole  discretion,  and  without  any
obligation to do so, acquire from BDEC or such  affiliate,  at the price offered
by (and upon the same terms  applicable  to) any third party  offer,  all of the
business  and  assets  of the ASC then held by BDEC or such  affiliate,  however
acquired by BDEC, prior to any sale or other transfer of the ASC, in whole or in
part, to any third party.  Upon  receiving  any such third party offer,  BDEC or
such affiliate shall give written notice thereof to Prime and Newco I. Following
its receipt of such notice,  Newco I shall have thirty (30) days to exercise the
ASC Option,  and Sellers agree that BDEC (or such  affiliates)  may not take any
action with  respect to the third party offer until Newco I has either  provided
written notice of its intent not to exercise the ASC Option,  or the thirty (30)
day period has  expired  without any  election  by Newco I to  exercise  the ASC
Option.  The closing of any purchase and sale pursuant to an exercise of the ASC
Option shall occur within 30 business  days  following  such  exercise,  and the
purchase price shall be paid, at Newco I's sole election,  in either immediately
available  funds or such other manner as shall have been set forth in the notice
of third party offer. In connection with any exercise of the ASC Option by Newco
I, BDEC shall deliver all agreements,  documents,  instruments and certificates,
and  take  such  other  action,  as may be  reasonably  necessary  in  order  to
consummate the purchase and sale contemplated in this Section. The parties agree
that  any  acquisition   pursuant  to  exercise  of  the  ASC  Option  shall  be
accomplished through an asset purchase, unless the parties otherwise agree.

         4.7      Repurchase Option.

     (a) At any time  prior to the  expiration  of one (1)  year  following  the
Effective  Time,  and  thereafter at any time within thirty (30) days after BDEC
becomes aware of the occurrence of a Bankruptcy Event (as defined in Section 8.4
hereof)  with  respect  to PMSI or Prime,  BDEC shall have the right to elect to
purchase  from Prime (the  "Repurchase  Option")  all (but not less than all) of
Prime's interest in Newco II.

                  (b) The Repurchase Option may be exercised,  in whole, and not
in part,  by the  delivery  by BDEC of  written  notice  to  Newco II and  Prime
specifying  that such  option  is being  exercised  and a closing  date for such
purchase  (which  shall be no sooner  than  thirty  (30) days and no later  than
ninety (90) days following the date of such written notice).  The purchase price
(the  "Repurchase  Price") to be paid upon the closing of the purchase under the
Repurchase  Option shall be paid to Prime and shall equal sixty percent (60%) of
(x) the  immediately  preceding  twelve (12) months' EBITDA  attributable to the
business and  operations of Newco II, as of the effective  time of the purchase,
multiplied  by (y) six (6);  but, in no event may the  Repurchase  Price be less
than $8,807,000.  Prime,  Newco II and BDEC shall deliver such other agreements,
documents,  instruments and certificates,  and take such other action (including
without  limitation  voting  their  ownership  interest  in Newco II), as may be
reasonably  necessary in order to  consummate  the purchase and sale pursuant to
exercise of the Repurchase Option. For purposes of this Agreement,  the "EBITDA"
of an entity or  business,  or interest  therein,  shall mean the net  operating
earnings of such entity or business  (or  portion  thereof  attributable  to the
interest  therein),  to the extent such net  operating  earnings are  reasonably
expected  to be  recurring  based  on  information  available  at  the  date  of
calculation,  calculated  without deduction of interest expense,  federal income
taxes,  depreciation  expense or amortization  expense, and all as determined in
accordance with GAAP to the extent GAAP is not inconsistent  with the definition
described in this sentence.

                  (c) In  return  for the  grant by  Newco II of the  Repurchase
Option,  BDEC agrees that, for a period of five (5) years immediately  following
the  closing  of the  sale and  purchase  pursuant  to  BDEC's  exercise  of the
Repurchase Option, if any (the "Repurchase Option Closing"),  BDEC may not sell,
transfer,  assign or  otherwise  dispose  of any  interest  in the Assets or the
Business (each of which,  for purposes of this subsection (c), shall include all
assets or business acquired in replacement of,  substitution for,  incidental to
or in  connection  with the Assets or the Business)  without  first  offering in
writing all of the Assets and the  Business to Prime (the "Prime  Right of First
Refusal").  Such  offer  shall set forth the terms of any third  party  offer to
acquire the Assets and the Business (or any substantial  portion  thereof),  and
Prime shall be entitled to exercise the Prime Right of First Refusal for:

                           (i) if such offer is  received  within the first year
         following the Repurchase Option Closing, a purchase price determined by
         (A) calculating the  immediately  preceding  twelve (12) months' EBITDA
         attributable  to the Assets and the Business,  as of the effective time
         of the purchase  pursuant to this  subsection  (c), and (B) multiplying
         such  amount by six (6);  provided,  however,  that if such third party
         offer is from any person or entity that controls,  is controlled by, or
         is under  common  control with BDEC,  the  purchase  price shall be the
         lesser of the purchase  price  determined  pursuant to this  subsection
         (c)(i) and the purchase price determined pursuant to subsection (c)(ii)
         below, or

     (ii) if such offer is received  within the second,  third,  fourth or fifth
years following the Repurchase  Option Closing,  the purchase price set forth in
such third party offer (adjusted proportionately, if applicable, to apply to all
of the Assets and the Business).

                  Upon  exercise  of the Prime Right of First  Refusal,  each of
Prime and BDEC shall deliver such other agreements,  documents,  instruments and
certificates,  and take such other  action,  as may be  reasonably  necessary in
order to consummate  the purchase and sale of the Assets and the Business on the
same terms and  conditions as proposed by the third party,  other than price and
except as set forth in subsection (d) below. In order to ensure the availability
of the rights  granted to Prime under this  subsection  (c),  BDEC agrees  that,
during the five (5)-year period following its exercise of the Repurchase Option,
it shall not sell,  transfer,  assign or otherwise  dispose of any of its right,
title or  interest  in and to any of the  Assets  or the  Business  (other  than
dispositions  in the ordinary  course of business,  dispositions  of items being
replaced,  or dispositions that, when considered with related  dispositions,  do
not exceed  $500 in value),  unless and until BDEC has given  Prime the  written
offer  required  hereunder  and Prime has, in each case,  either (I) declined in
writing to purchase  the Assets and the  Business,  or (II) failed to respond to
BDEC  within  thirty (30)  business  days  following  its receipt of the written
offer.

     (d) The parties agree that any  acquisition  pursuant to an exercise of the
Prime Right of First Refusal  shall be  accomplished  through an asset  purchase
unless the parties  otherwise  agree. In addition,  Prime may elect, in its sole
discretion,  to pay the purchase  price in cash at the closing,  and such method
shall be an  acceptable  form of  payment,  regardless  of the  form of  payment
contemplated in the third party offer.

     4.8 Forfeiture of Warrants,  Certain Other Rights. In addition to any other
forfeiture  of or  limitation  on  rights  granted  to the  Sellers  under  this
Agreement, each of the Sellers acknowledges and agrees that all Primary Warrants
and Target Center Warrants shall irrevocably  terminate  immediately and without
notice     upon     the     occurrence     of    any    of    the     following:
- --------------------------------------------

     (a) Any exercise by BDEC of the  Repurchase  Option granted in Section 4.7;
or
     (b) Any breach by any of the Sellers under any of the Transaction Documents
or any agreement,  contract, document or instrument executed by such Seller that
inures to the benefit of Newco I, Newco II, Prime, or any of Prime's affiliates,
including,  without  limitation,  (i) any Consulting  Agreement (as  hereinafter
defined) to which such Seller is a party and (ii) any note or security agreement
to which such Seller is a party.

     4.9 Insurance.  Newco I and Newco II agree to maintain,  for five (5) years
after the  Closing  Date,  a prior acts  insurance  policy  providing  insurance
coverage  of the  same  scope,  in the  same  amounts  and  subject  to the same
deductibles as the BDEC's insurance in effect  immediately  prior to the Closing
Date. ---------

     4.10  Guaranty  of  PMSI.  PMSI  hereby   unconditionally  and  irrevocably
guarantees  each of the payment and  performance  obligations of Prime hereunder
and under each of the  Transaction  Documents.  Without  limiting the foregoing,
PMSI  agrees  that  if  Prime  shall  default  in any  obligation  to pay to any
Seller(s) or Newco I any amount then due and payable by Prime to such  Seller(s)
or Newco I under ARTICLE I or ARTICLE VII hereunder,  PMSI shall immediately pay
such amount to such Seller(s) or Newco ----------------

     I. PMSI hereby agrees not to require any Seller to proceed against Prime or
     any other person or to pursue any other remedy  before  proceeding  against
     PMSI under this guaranty.

         4.11  Tucson  Earnout.  Prime and BDEC  acknowledge  and agree that the
assets located at 555 E. River Road, Tucson,  Arizona (the "Tucson Assets"), and
any business  conducted using the Tucson Assets (the "Tucson  Operations"),  are
included within the Assets and Business and are, pursuant to Section 1.1 of this
Agreement, transferred to Newco II as of the Effective Time. In consideration of
the transfer of the Tucson  Assets and the Tucson  Operations to Newco II, Prime
agrees to pay, after September 1, 2000, in accordance with the provisions below,
an amount equal to sixty  percent  (60%) of the Tucson Gross Value (the "Earnout
Payment"). For purposes of this Section, "Tucson Gross Value" shall mean (a) six
(6) times the recurring EBITDA arising solely from the Tucson Operations between
the dates of September 1, 1999 and  September  1, 2000 (the  "Earnout  Period"),
minus  (b)  the  amount  of  all  debt,   liabilities  and  other   obligations,
collectively,  incurred  by Newco II that  relate  to the  Tucson  Assets or the
Tucson Operations, and that arose during the Earnout Period (excluding, however,
accounts  payable  and  accrued   liabilities   arising  from  normal  operating
expenses).  On or prior to November 1, 2000,  Prime  shall  provide  BDEC with a
written statement setting forth the Earnout Payment.  Following delivery of such
statement,  BDEC shall have  thirty  (30) days  during  which it may dispute the
calculation of the Earnout Payment,  and any dispute shall be resolved  pursuant
to the  arbitration  provisions  of this  Agreement.  If BDEC  agrees  with  the
calculation of the Earnout Payment,  or fails to respond within such thirty (30)
day period,  then the amount of the Earnout  Payment  reflected in the statement
shall be final and  binding on both BDEC and  Prime.  Promptly  following  final
determination  of the amount of the Earnout  Payment  pursuant to this  Section,
Prime  shall  pay  the  Earnout  Payment  in  immediately  available  funds.  In
connection  with the  payment of the  Earnout  Payment by Prime,  BDEC agrees to
deliver all agreements,  documents,  instruments and certificates, and take such
other action, as may be reasonably necessary in order to evidence the conveyance
of the Tucson Assets and Business pursuant to Section 1.1 of this Agreement.

                                   ARTICLE V )

                             Conditions to Closing )

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is   a   condition   to   the    obligations   of   each   Seller   to   Close):
- ---------------------------

     (a) pay the Purchase Price to BDEC;

     (b) ensure that the Primary Warrants are delivered to BDEC;

     (c) execute  and  deliver the  Assignment  and  Assumption  Agreement,  the
Organizational  Documents,  the Credit Documents to which it is a party and each
other Transaction Document to which it is a party; and

          (d) deliver such good standing certificates, officer certificates, and
     similar  documents  and  certificates  as counsel  for BDEC may  reasonably
     require.  5.2 Sellers  Closing  Obligations.  At the  Closing,  each Seller
     shall,  as applicable  (each of which is a condition to the  obligations of
     Prime to Close): ---------------------------

          (a) execute and deliver the Assignment and Assumption  Agreement,  the
     Organizational  Documents,  the  Collocation  and Employee and Cost Sharing
     Agreement  substantially  in the form  attached  hereto  as  Exhibit I (the
     "Collocation  Agreement"),  the Credit Documents, and the other Transaction
     Documents, in each case, only where it is a party thereto; ---------

          (b)  except  for LASIK  and BDEC,  execute  and  deliver a  consulting
     agreement,  in  substantially  the form  attached  hereto as Exhibit J (the
     "Consulting Agreement");

          (c) cause  each  owner of BDEC and LASIK who is not a  "Seller"  under
     this Agreement to execute and deliver,  for the benefit of Prime,  PMSI and
     their affiliates,  a non-compete  agreement containing terms and provisions
     consistent  with  those  contained  in  Sections  9.3  through  9.7 of this
     Agreement;

          (d)  deliver  or cause to be  delivered  true and  correct  copies  of
     executed consents whereby Barnet, Dulaney,  Rosenberg,  Perkins and Pinkert
     and other managers, officers and/or members of BDEC or LASIK have, in their
     respective  capacities  as  managers,  officers  and/or  members of BDEC or
     LASIK, as applicable,  each approved of and ratified (as necessary)  BDEC's
     or LASIK's execution and delivery of, and performance under, this Agreement
     and each Transaction Document; and

          (e) deliver such good standing certificates, officer certificates, and
     similar  documents  and  certificates  as counsel for Prime may  reasonably
     require.

          5.3 Newco  I's  Closing  Obligations.  At the  Closing,  Newco I shall
     execute  and  deliver  the Credit  Documents  to which it is a party,  each
     Transaction  Document  to  which  it is a  party  and  such  good  standing
     certificates,  officer certificates, and similar documents and certificates
     as  counsel  for  Prime  or any  of the  Sellers  may  reasonably  require.
     --------------------------------------

          5.4 Newco II's Closing  Obligations.  At the  Closing,  Newco II shall
     execute  and  deliver  the  Assignment  and   Assumption   Agreement,   the
     Collocation  Agreement,  the Credit Documents to which it is a party,  each
     Transaction  Document  to  which  it is a  party  and  such  good  standing
     certificates,  officer certificates, and similar documents and certificates
     as  counsel  for  Prime  or any  of the  Sellers  may  reasonably  require.
     ---------------------------------------

                                  ARTICLE VI )

                 Indemnification of Prime, Newco I and Newco II
                                       )

         6.1 Indemnification of Prime, Newco I and Newco II.

                  (a) BDEC and  LASIK,  each  jointly  and  severally,  agree to
indemnify and hold harmless  Prime,  each subsidiary  and/or  affiliate of Prime
(including,  without  limitation,  PMSI), each officer,  director,  shareholder,
manager,  member,  partner,  employee,  agent, or  representative  of Prime and,
following  the  Closing,  Newco  I  and  Newco  II  (collectively,   the  "Prime
Indemnified  Parties"),  from and against any and all damages,  losses,  claims,
liabilities,  demands, charges, suits, penalties, costs, and expenses (including
court costs and  attorneys'  fees and  expenses  incurred in  investigating  and
preparing for any litigation or proceeding) (collectively,  "Indemnified Costs")
in  connection  with the  commencement  or assertion of any action,  proceeding,
demand, or claim by a third party (collectively,  a "third-party  action") which
any of the Prime Indemnified Parties may sustain,  arising out of (i) any breach
or default by any Seller of any of the representations, warranties, covenants or
agreements  contained in this Agreement or any Transaction  Document (including,
without  limitation,  the  Organizational  Documents),  (ii) any  obligation  or
liability  of BDEC not  assumed  by  Newco II  pursuant  to the  Assignment  and
Assumption  Agreement,  (iii) any transaction or occurrence involving or related
to the ASC or PRG or any  purchase of the assets of the ASC by BDEC  (including,
without limitation,  claims by a trustee in bankruptcy), or (iv) any obligations
or liabilities with respect to any claims arising out of actions or omissions by
any Seller  (excluding any acts or omissions  after the Closing in such Seller's
capacity as a member of Newco I or Newco II.

                  (b) Each of Dulaney, Barnet and Rosenberg,  severally, and not
jointly, agrees to indemnify and hold harmless each Prime Indemnified Party from
and against  any and all  Indemnified  Costs  incurred  in  connection  with the
commencement  or  assertion  of any  third-party  action  which any of the Prime
Indemnified Parties may sustain,  arising out of any breach or default by him of
any of the representations,  warranties,  covenants or agreements made by him in
this Agreement or any Transaction Document (including,  without limitation,  the
Organizational Documents).

          6.2 Defense of Third-Party  Claims.  A Prime  Indemnified  Party shall
     give  prompt   written  notice  to  the   indemnifying   party  or  parties
     (collectively,  the "indemnifying  party") of the commencement or assertion
     of any third party action in respect of which such Prime  Indemnified Party
     shall  seek  indemnification  hereunder.  Any  failure  to  so  notify  the
     indemnifying  party  shall not  relieve  the  indemnifying  party  from any
     liability  that it may have to such  Prime  Indemnified  Party  under  this
     ARTICLE  -----------------------------  unless  the  failure  to give  such
     notice  materially and adversely  prejudices the  indemnifying  party.  The
     indemnifying  party  shall have the right to assume  control of the defense
     of, settle, or otherwise  dispose of such third-party  action on such terms
     as it deems appropriate; provided, however, that:

                  (a) The Prime  Indemnified  Party shall be  entitled,  at his,
her, or its own  expense,  to  participate  in the  defense of such  third-party
action;

          (b) The indemnifying  party shall obtain the prior written approval of
     the Prime  Indemnified  Party,  which  approval  shall not be  unreasonably
     withheld,  before  entering  into or  making  any  settlement,  compromise,
     admission,  or acknowledgment of the validity of such third-party action or
     any  liability  in respect  thereof if,  pursuant to or as a result of such
     settlement,  compromise, admission, or acknowledgment,  injunctive or other
     equitable relief would be imposed against the Prime Indemnified Party;

          (c) The  indemnifying  party  shall  not  consent  to the entry of any
     judgment or enter into any  settlement  with or  involving  any claimant or
     plaintiff  that does not  include  as an  unconditional  term  thereof  the
     execution  and delivery of a release from all  liability in respect of such
     third-party  action by such claimant or plaintiff to, and in favor of, each
     Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to  participate  at their own expense in the defense of),
and the Prime Indemnified Party shall be entitled to have sole control over, the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying party or BDEC, without the
prior written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

          (f)  The  parties  hereto  shall  extend  reasonable   cooperation  in
     connection  with the  defense of any  third-party  action  pursuant to this
     ARTICLE  and,  in  connection   therewith,   shall  furnish  such  records,
     information,   and  testimony  and  attend  such   conferences,   discovery
     proceedings, hearings, trials, and appeals as may be reasonably requested.

        6.3  Security.  Without  limiting or adversely  affecting the rights of
Prime under Section 9.12,  and in order to secure full and prompt payment of the
obligations  of each of the Sellers under this  ARTICLE,  each of BDEC and LASIK
hereby grants to Prime a continuing  security  interest in and to  distributions
either of them may be  entitled  to  receive  at any time  after the  Closing in
respect of any  ownership  interest  held by either of them in either Newco I or
Newco II. In connection with the grant of a security interest  contained in this
Section, each of BDEC and LASIK agrees (i) to execute all documents, agreements,
instruments and certificates,  and to take such other actions,  as are necessary
in order to fully evidence and perfect such security interest, and (ii) that it,
for a period of five (5) years after the Closing,  will not,  without  obtaining
the express prior written consent of Prime in each instance,  grant or assign to
any person or entity  rights of any nature in the  distributions  covered by the
security  interest granted in this Section,  irrespective of whether such rights
are to be senior or subordinate to the rights granted under this Section.

                                   ARTICLE VII

                           Indemnification of Sellers


         7.1  Indemnification  of Sellers.  Prime agrees to  indemnify  and hold
harmless  each Seller,  each  subsidiary  and/or  affiliate of any Seller,  each
officer,  director,  shareholder,  manager, member, partner, employee, agent, or
representative  of any Seller and,  following the Closing,  Newco I and Newco II
(collectively,  the "Seller  Indemnified  Parties") from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of Seller Indemnified Parties may sustain, arising out of
(i) any breach or default  by Prime of any of the  representations,  warranties,
covenants or agreements  contained in this Agreement or any Transaction Document
(including,  without  limitation,  the  Organizational  Documents)  or (ii)  any
obligations  or  liabilities  with  respect  to  claims  arising  out of acts or
omissions  (excluding any acts or omissions after the Closing in its capacity as
a  member  of  Newco I or Newco  II) by  Prime,  PMSI or one or more of the PMSI
Controlled Parties (excluding Newco I and Newco II).

          7.2 Defense of Third-Party  Claims. A Seller  Indemnified  Party shall
     give prompt written notice to Prime of the commencement or assertion of any
     third party action in respect of which such Seller  Indemnified Party shall
     seek  indemnification  hereunder.  Any failure to so notify Prime shall not
     relieve  Prime  from  any  liability  that  it  may  have  to  such  Seller
     Indemnified Party under this ARTICLE unless the failure to give such notice
     materially   and   adversely    prejudices   Prime.    Prime   shall   have
     -----------------------------  the right to assume  control of the  defense
     of, settle, or otherwise  dispose of such third-party  action on such terms
     as it deems appropriate; provided, however, that:

          (a) The Seller Indemnified Party shall be entitled,  at his or its own
     expense, to participate in the defense of such third-party action;

          (b) Prime  shall  obtain  the prior  written  approval  of the  Seller
     Indemnified  Party,  which  approval  shall not be  unreasonably  withheld,
     before entering into or making any settlement,  compromise,  admission,  or
     acknowledgment of the validity of such third-party  action or any liability
     in  respect  thereof  if,  pursuant  to or as a result of such  settlement,
     compromise,  admission,  or  acknowledgment,  injunctive or other equitable
     relief would be imposed against the Seller Indemnified Party;

          (c) Prime shall not consent to the entry of any judgment or enter into
     any  settlement  with or involving any claimant or plaintiff  that does not
     include as an  unconditional  term thereof the  execution and delivery of a
     release from all  liability in respect of such  third-party  action by such
     claimant or plaintiff to, and in favor of, each Seller  Indemnified  Party;
     and

          (d) Prime shall not be  entitled to control  (but shall be entitled to
     participate  at its  own  expense  in  the  defense  of),  and  the  Seller
     Indemnified  Party shall be entitled to have sole control over, the defense
     or settlement,  compromise, admission, or acknowledgment of any third-party
     action as to which  Prime fails to assume the  defense  within  thirty (30)
     days;  provided,  however,  that the Seller Indemnified Party shall make no
     settlement,  compromise, admission, or acknowledgment which would give rise
     to liability (other than liability to Seller Indemnified Parties under this
     Agreement) on the part of Prime without the prior written consent of Prime.

          (e) Prime  shall make  payments  of all  amounts  required  to be made
     pursuant to the foregoing  provisions of this ARTICLE to or for the account
     of the Seller  Indemnified Party from time to time promptly upon receipt of
     bills or  invoices  relating  thereto or when  otherwise  due and  payable,
     provided  that the  Seller  Indemnified  Party  has  agreed in  writing  to
     reimburse  Prime  for the  full  amount  of  such  payments  if the  Seller
     Indemnified  Party is  ultimately  determined  not to be  entitled  to such
     indemnification.

          (f)  The  parties  hereto  shall  extend  reasonable   cooperation  in
     connection  with the  defense of any  third-party  action  pursuant to this
     ARTICLE  and,  in  connection   therewith,   shall  furnish  such  records,
     information,   and  testimony  and  attend  such   conferences,   discovery
     proceedings, hearings, trials, and appeals as may be reasonably requested.

                                  ARTICLE VIII

                                   Exclusivity

         8.1 Agreement.  Each of the parties to this Agreement  (excluding Newco
I) agrees that,  following  the Closing Date, it will not directly or indirectly
through  any  affiliate,  except  through  Newco  I or one of its  wholly  owned
subsidiaries,  acquire,  develop  or  establish  other  centers  for  Refractive
Surgery,  or  the  assets  thereof,  anywhere  in  the  United  States  ("Target
Centers");  provided,  however,  Prime, PMSI or one of their affiliates shall be
entitled to independently  acquire or develop any Target Center to which any one
or more of the following apply:

          (a) The  aggregate  purchase  price paid to the seller of such  Target
     Center exceeds $11,009,000;

                  (b) Newco I is  financially  unable to acquire or develop such
Target Center using its existing financial resources  (including  resources that
may be available in such instance under the  Development  Facility and any other
lines of credit or credit  facilities)  without  requiring a guarantee  or other
financial  or credit  assistance  of any member of Newco I,  Prime,  PMSI or any
affiliate  of Prime or PMSI,  as  determined  conclusively  in each  instance by
either (i) the  agreement of not less than eighty  percent (80%) of the managers
of Newco I or (ii) the  failure  of Newco I to  close  the  acquisition  of such
Target Center within one hundred twenty (120) days following  Newco I's and such
Target Center's  agreement on the initial  principal  terms of such  acquisition
(which agreement  includes,  without  limitation,  agreement on a terms sheet or
execution of a  non-binding  letter of intent)  because Newco I could not obtain
financing on reasonable market terms;

          (c) The  managers of Newco I decide not to pursue the  acquisition  or
     development of such Target Center by the affirmative  vote of not less than
     eighty  percent (80%) of the managers then serving on the board of managers
     of Newco I;

          (d) In the  opinion of the board of  directors  of PMSI,  such  Target
     Center  cannot  be  acquired  or  developed  by  Newco  I  because  of  the
     involvement with and/or direct or indirect  ownership of a portion of Newco
     I by any of Dulaney, Barnet or Rosenberg;

          (e)  The   acquisition  or  development  of  such  Target  Center  was
     initiated,  arranged for,  originated or financed by any entity  affiliated
     with PMSI  (other than Newco I or Newco II, or any future  subsidiaries  of
     either of them) which has previously acquired or developed a Target Center,
     or an interest  therein,  pursuant to any of the  exceptions to exclusivity
     contained in subsections (a) through (g) of this Section;

                  (f)  Any  of  Dulaney,  Barnet  or  Rosenberg  has  previously
terminated,  breached or  threatened  to breach any  Transaction  Document,  any
Credit Document,  any Target Center Lending Document or any Consulting Agreement
to which he is a party (provided,  however, that (A) each of Barnet, Dulaney and
Rosenberg  shall have  thirty  days  within  which to cure any breach or default
under his respective  Consulting  Agreement following delivery of notice of such
breach or default  by Prime or PMSI and (B) any  termination  of any  Consulting
Agreement  that is agreed to in writing by Prime,  or that is done to permit the
agreed upon full time employment of the respective individual by Newco II, shall
not be grounds for  exception  to the  exclusivity  obligation  pursuant to this
subsection (f)); or

          (g) the  Closing  does not occur on or before July 31, 1999 and Prime,
     PMSI or any of their affiliates enters into a definitive  agreement for the
     acquisition  of such Target  Center prior to the  expiration  of forty five
     (45) days immediately following the Closing.

          8.2  Additional  Qualifications,   Limitations.  In  addition  to  the
     qualifications  and limitations set forth above, the following shall apply:
     --------------------------------------

          (a) All  acquisitions of Target Centers must be approved in advance by
     a majority of the board of directors of Prime;

          (b) If the exclusivity  obligation contained in Section 8.1 above does
     not apply to a particular  Target Center solely  because of the  limitation
     set forth in Section  8.1(a),  and Prime or one of its affiliates  acquires
     such Target Center prior to the  occurrence of any of the events  described
     in Section 8.1(f), then

                           (i) before  consummating such  acquisition,  Prime or
         its acquiring  affiliate  shall provide thirty (30) days' prior written
         notice to LASIK of such pending  acquisition,  and LASIK shall have ten
         (10)  days from its  receipt  of such  notice  to  notify  Prime or its
         acquiring  affiliate  that  LASIK  would  like to  acquire a  specified
         portion  of up to forty  percent  (40%) of the  non-medical  Refractive
         Surgery portion of the interest being offered to Prime or its acquiring
         affiliate  in such  acquisition,  upon the same  terms  and  conditions
         agreed to by Prime;  provided,  however,  that the participation  right
         granted  in this  subsection  (i)  shall  not apply if (A) Prime or its
         acquiring  affiliate does not receive notice from LASIK of its election
         to  participate  in such  acquisition  within the ten  (10)-day  period
         provided  for such  notice,  (B) LASIK  refuses or is unable to finance
         (after giving effect to subsection (ii) below) its specified portion of
         the  acquisition,  (C) LASIK  refuses  or is unable to timely  execute,
         deliver and perform all agreements,  documents and instruments required
         to be executed, delivered and performed by it (to the extent consistent
         with  those  executed  by  Prime  or its  acquiring  affiliate  in such
         transaction)  or (D)  LASIK  fails or  refuses  to timely  execute  and
         deliver the promissory note and security agreement described in Section
         8.2(e)  below  in  the  event  LASIK  borrows  any  funds  pursuant  to
         subsection (ii) below;

                           (ii) If LASIK has fully complied with its obligations
         and met all other conditions set forth under subsection (i), then, with
         respect to that portion of the purchase price to be paid by LASIK under
         subsection (i) ("LASIK's  Purchase Price"),  LASIK shall be entitled to
         request in writing and receive  financing,  made  available by Prime or
         one of its affiliates,  in an amount not to exceed ten percent (10%) of
         the aggregate  purchase price for the  non-medical  Refractive  Surgery
         portion  of the  interest  being  offered  to  Prime  or its  acquiring
         affiliate in such  acquisition  (but in no event may such amount exceed
         LASIK's Purchase Price);  provided,  however,  that LASIK's rights, and
         Prime's or its acquiring affiliate's obligations, under this subsection
         (ii) are subject  entirely  and in all  respects  to Prime's  obtaining
         prior  written  approval  from  (A)  the  bank  syndication  under  its
         outstanding  borrowing  facilities,  and (B) any  necessary  number  of
         holders of Prime's  outstanding  8 3/4 Senior  Subordinated  Promissory
         Notes (as may be required  pursuant  to the  Indenture  governing  such
         Notes);

                  (c) If the  exclusivity  obligation  contained  in Section 8.1
above does not apply to the  acquisition  of a particular  Target  Center solely
because of the  limitation set forth in Section  8.1(d) or Section  8.1(e),  and
Prime  or one  of its  affiliates  acquires  such  Target  Center  prior  to the
occurrence of any of the events described in Section 8.1(f),  then LASIK (or any
combination of the  principals of LASIK,  but only pursuant to and in the manner
provided for in written instructions  delivered to PMSI and Prime by LASIK prior
to such acquisition) shall receive warrants in connection with such acquisition,
in  substantially  the form  attached  hereto as Exhibit A (the  "Target  Center
Warrants"),  entitling LASIK or such other person(s) to purchase, at one hundred
ten  percent  (110%) of PMSI's  closing  share  price as quoted by NASDAQ on the
closing  date of the  acquisition  of such Target  Center,  that whole number of
shares of common stock of PMSI determined by:

          (i) if the  Target  Center  is  acquired  solely  in  reliance  on the
     exception contained in Section 8.1(d),  multiplying (i) 0.0075, by (ii) the
     portion of the  purchase  price,  expressed as a number and not in dollars,
     paid by Prime or its  acquiring  affiliate  in  respect  of the  Refractive
     Surgery operations of such Target Center (specifically  excluding the value
     of any  non-Refractive  Surgery  operations  of such Target Center that are
     acquired pursuant to subsection (h) below); and

          (ii) if the  Target  Center  is  acquired  solely in  reliance  on the
     exception contained in Section 8.1(e),  multiplying (i) 0.0025, by (ii) the
     portion of the  purchase  price,  expressed as a number and not in dollars,
     paid by Prime or its  acquiring  affiliate  in  respect  of the  Refractive
     Surgery operations of such Target Center (specifically  excluding the value
     of any  non-Refractive  Surgery  operations  of such Target Center that are
     acquired pursuant to subsection (h) below);

          (d) The rights granted under Section 8.2(b) are personal to LASIK and,
     notwithstanding any other provision of this Agreement,  may not be assigned
     to or exercised by any other party;

                  (e) Any and all  amounts  loaned to LASIK  pursuant to Section
8.2(b)(ii)  above shall be evidenced by a  promissory  note which shall  provide
that,  among other things (i) such amounts  shall bear interest at the per annum
rate of fifteen  percent  (15%) or,  following  any  default by LASIK under such
promissory note or under any other agreement, document or instrument executed by
LASIK for the  benefit of Prime,  PMSI or one of their  affiliates,  the maximum
rate  allowed  by law,  (ii)  such  amounts  shall be  repaid  in equal  monthly
installments  of principal and interest over a period of sixty (60) months,  and
(iii) the promissory note shall be governed by Texas law;  provided further that
such amounts shall be secured by a security  agreement executed and delivered by
LASIK to Prime or its acquiring  affiliate,  securing all of LASIK's obligations
under such promissory note with all of LASIK's right,  title and interest in and
to the Target Center being  acquired (all notes,  security  agreements and other
agreements,  documents,  instruments or certificates  required to be executed by
any party pursuant to this  subsection (e) are referred to herein as the "Target
Center Lending  Documents," and all Target Center Lending  Documents shall be in
form and substance  reasonably  satisfactory to Prime and,  unless  specifically
specified otherwise,  shall be deemed included in the Transaction  Documents for
purposes of this Agreement, regardless of when executed);

                  (f) LASIK agrees that,  notwithstanding any other provision of
this Agreement or the Transfer Restriction  Agreement,  it shall not be entitled
to transfer or assign, to any person or entity,  any direct or indirect interest
in any Target  Center  acquired  by it  pursuant  to the  provisions  of Section
8.2(b)(ii),  until such time as (i) LASIK has irrevocably  forfeited any and all
rights  to  borrow  funds  pursuant  to  Section  8.2(b)(ii)  above  (either  by
termination  of such  rights  pursuant  to the  terms  of this  Agreement  or by
delivery by LASIK to Prime of an  irrevocable,  perpetual and binding  waiver of
such rights) and (ii) there are no amounts  (including  principal  and interest)
outstanding  under any promissory note previously  executed by LASIK pursuant to
Section  8.2(b)(ii);  provided further,  that any transfer or assignment of such
interest in any such Target Center in violation of this subsection shall be null
and void and shall not be given effect by PMSI, Prime or any other party to this
Agreement;

                  (g)  Notwithstanding the exclusivity  obligation  contained in
Section 8.1, LASIK and/or one or more of their  affiliates  shall be entitled to
independently  acquire or develop any Target  Center to which any one or more of
the  following  apply:  (i) a majority of the board of  directors of Prime votes
against the  acquisition  of such Target  Center;  or (ii) Newco II is unable to
finance the  acquisition of such Target Center using the  Development  Facility,
solely because of the limitation set forth in Section 4.3(c); provided, however,
that:

          (y) in either  instance,  LASIK or its  affiliates  must  acquire such
     Target Center within one hundred  twenty (120) days after the occurrence or
     circumstances  that triggered the  application of this  subsection (g), and
     upon any failure to so acquire such Target  Center  within such one hundred
     twenty (120) day period,  the exclusivity  obligation  contained in Section
     8.1 shall again apply with respect to such Target Center; and

                           (z) with respect to the exception to exclusivity  set
         forth in subsection (ii) of this subsection (g), before LASIK or one of
         its  affiliates  acquires  such Target  Center,  LASIK or its acquiring
         affiliate shall provide thirty (30) days' prior written notice to Prime
         of such  pending  acquisition,  and Prime shall have ten (10) days from
         its receipt of such notice to notify LASIK or its  acquiring  affiliate
         that Prime  would like to  acquire a  specified  portion of up to forty
         percent  (40%) of the interest  being offered to LASIK or its acquiring
         affiliate  in such  acquisition,  upon the same  terms  and  conditions
         agreed to by LASIK;  provided,  however,  that the participation  right
         granted  in this  subsection  (z)  shall  not apply if (A) LASIK or its
         acquiring  affiliate does not receive notice from Prime of its election
         to  participate  in such  acquisition  within the ten  (10)-day  period
         provided for such notice, (B) Prime refuses or is unable to finance its
         specified portion of the acquisition, or (C) Prime refuses or is unable
         to timely execute,  deliver and perform all  agreements,  documents and
         instruments required to be executed,  delivered and performed by it (to
         the extent  consistent  with those  executed by LASIK or its  acquiring
         affiliate in such transaction); and

                  (h) The exclusivity  obligation contained in Section 8.1 shall
not  restrict  Prime  or  PMSI,  or  any  affiliate  of  either  of  them,  from
independently acquiring, all or any portion of the non-Refractive Surgery assets
and business of a Target  Center to the extent those assets and business are not
used  primarily  in, or  materially  relied on for,  the  conduct of  Refractive
Surgery by such Target  Center,  and LASIK shall not,  with  respect to any such
acquisition,  be entitled  to any of the rights  granted in this  ARTICLE  VIII,
including without  limitation,  the rights granted in subsections (b) and (c) of
this Section.

          8.3 Effect.  No provision of this ARTICLE VIII,  shall be construed to
     require any party to this Agreement to purchase any Target Center. ------

          8.4 Automatic  Termination.  This entire ARTICLE VIII shall  terminate
     and become null and void automatically:

                  (a) if any party to this Agreement:  (i) becomes insolvent, or
makes a transfer in fraud of creditors,  or makes an assignment  for the benefit
of creditors, or admits in writing its inability to pay its debts as they become
due; (ii) generally is not paying its debts as such debts become due, and one of
the other parties, in good faith,  determines that such event or condition could
frustrate the operation of this ARTICLE VIII or otherwise inhibit the delinquent
party's  ability  to  perform  its  obligations  under  this  Agreement  or  any
Transaction Document; (iii) has a receiver,  trustee or custodian appointed for,
or take  possession  of, all or  substantially  all of the assets of such party,
either in a proceeding  brought by such party or in a proceeding brought against
such party;  (iv) files a petition for relief under the United States Bankruptcy
Code or any other present or future federal or state  insolvency,  bankruptcy or
similar laws (all of the foregoing  hereinafter  collectively called "Applicable
Bankruptcy  Law"),  or an involuntary  petition for relief is filed against such
party under any  Applicable  Bankruptcy  Law, or an order for relief naming such
party is  entered  under any  Applicable  Bankruptcy  Law,  or any  composition,
rearrangement,  extension,  reorganization  or other  relief of  debtors  now or
hereafter existing is requested or consented to by such party; (v) fails to have
discharged within a period of thirty (30) days any attachment,  sequestration or
similar writ levied upon,  or any claim  against or  affecting,  any property of
such  party;  or (vi)  fails to pay  within  thirty  (30) days any  final  money
judgment   against  such  party  (the  events  described  in  this  Section  are
hereinafter referred to as "Bankruptcy Events");

          (b) upon any exercise of the Repurchase Option granted in Section 4.7;

     (c)  if,  at  any  time  after  the   Closing,   Barnet  and  Dulaney  own,
     collectively,  less  than  sixty  percent  (60%) of the  total  outstanding
     ownership  interests of BDEC (after  assuming the  conversion,  exchange or
     exercise  of  any  and  all  securities  or  rights  convertible  into,  or
     exchangeable or exercisable for, ownership interests of BDEC); or

                  (d)  upon  the   expiration   of  the  five  (5)  year  period
immediately following the Closing Date.

                                                    ARTICLE IX

                                              Post Closing Agreements

         9.1 Transition of Business.  Each Seller agrees to cooperate fully with
Prime and Newco II in transitioning  the Business existing prior to the Closing,
including the  relationships  maintained by BDEC (with respect to the Business),
to Newco II after the Closing; and, each Seller agrees not to take any action or
make  any  disclosure,   including   disclosures  related  to  the  transactions
contemplated by this Agreement, which (with respect to the Business) might alter
or impair any relationship with any customer, or other service recipient, person
or entity which did business with BDEC prior to the Closing. With respect to the
Business, each Seller agrees to promptly remit to Newco II any payments received
by BDEC or any Seller for services provided by BDEC (as part of the Business) or
Newco II after the  Effective  Time.  Newco I,  Newco II and Prime each agree to
promptly remit to BDEC any payments received by it for services provided by BDEC
prior to the  Effective  Time.  Furthermore,  Sellers  agree to deposit any such
payments  received  directly to a deposit  account  designated and controlled by
Newco II or to take such other  action as may be requested by Prime to implement
and  maintain a system for  remitting  payments due Newco II which come into the
possession or control of BDEC or any Seller.

          9.2 Ratification by Newco I. Prime,  BDEC and LASIK each agree that by
     executing  this  Agreement  they are  deemed to be voting  their  ownership
     interests in Newco I and Newco II, as applicable,  to authorize Newco I and
     Newco  II to  enter  into  and  perform  this  Agreement  and  each  of the
     Transaction  Documents  to which either is a party.  Prime,  BDEC and LASIK
     each agree to execute such resolutions and written consents,  and take such
     other  actions,  in  their  capacities  as  members  of  Newco I and  Newco
     ----------------------- II, as any party shall reasonably require after the
     Closing  to have  Newco I and Newco II ratify  and  adopt  this  Agreement,
     notwithstanding the official date of Newco I's and Newco II's creation.

         9.3  Confidentiality  Agreement.  Each of Prime,  PMSI, and each Seller
acknowledges that through its relationship with Newco I and Newco II, it will be
exposed  to  Proprietary  Information  (as  defined  below) of Newco I, Newco II
and/or  each of their  present or future  affiliates  (which  includes,  without
limitation,  BDEC,  LASIK,  Prime,  PMSI  and each of their  present  or  future
affiliates) (the party owning such Proprietary Information is referred to as the
"Discloser"),  that such Proprietary Information is unique and valuable and that
such Discloser would suffer  irreparable  injury if its Proprietary  Information
were divulged to those in competition with Discloser.  "Proprietary Information"
shall be all information  concerning  Discloser  which a party  acquires,  or to
which it has access through its  relationship  with Discloser,  Newco I or Newco
II, that has not been publicly disclosed by Discloser or that is not a matter of
common knowledge among Discloser's  competitors,  including, but not limited to,
information relating to any inventions,  processes,  software,  formulae, plans,
devices, compilations of information,  technical data, mailing lists, management
strategies, business distribution methods, names of suppliers (of both goods and
services)  and   customers,   names  of  employees  and  terms  of   employment,
arrangements  entered into with  suppliers  and  customers,  including,  but not
limited to, proposed expansion plans of Discloser,  marketing and other business
and pricing strategies, and trade secrets of Discloser.

          Except with prior written approval of Discloser, Prime, PMSI, and each
     Seller agrees that it will not, at any time after the Closing: (i) directly
     or indirectly,  disclose any  Proprietary  Information to any person except
     its  owners,  directors,   managers,   officers,   employees,   agents  and
     consultants  who need to know such  Proprietary  Information  in connection
     with  such  party's  relationship  with  Newco I or  Newco  II nor (ii) use
     Proprietary  Information in any way,  except for the purposes of Newco I or
     Newco II.

         Within  forty-eight  (48) hours of  termination  of its ownership of or
consulting  relationship  with  Newco I or  Newco  II,  as  applicable,  whether
voluntary  or  involuntary,  Prime,  PMSI,  and each Seller will  deliver to the
appropriate Discloser (without retaining copies thereof) all documents,  records
or other  memorializations  including copies of documents and any notes which it
has  prepared  that  contain   Proprietary   Information,   all  other  tangible
Proprietary  Information  in its  possession  or control and all of  Discloser's
credit cards, keys, equipment,  vehicles,  supplies and other materials that are
in its possession or under its control.

         9.4 Non-Competition Agreement. Each of PMSI, Prime, and each Seller, as
a material inducement to one another to enter into this Agreement, hereby agrees
that, at all times during which the  provisions of ARTICLE VIII are  applicable,
and at all times  until five (5) years  after  either  LASIK and its  affiliates
(excluding  PMSI,  Prime,  and the subsidiaries of either of them), or Prime and
its affiliates  (excluding LASIK), no longer own any equity or other interest in
Newco I, such party will not directly or indirectly,  either through any kind of
ownership  (other than ownership of securities of a publicly held corporation of
which  it  owns  less  than  five  percent  (5%)  of any  class  of  outstanding
securities),  or  as  a  principal,   shareholder,   agent,  employer,  advisor,
consultant, co-partner or in any individual or representative capacity whatever,
either for its own benefit or for the benefit of any other  person,  corporation
or other entity,  without the prior written  consent of each other party hereto,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except through Newco I or its  subsidiaries,  or Newco II,
directly or indirectly engage in, or provide,  anywhere within a fifty (50) mile
radius of any center or facility that provides  Refractive Surgery and is owned,
directly or indirectly, partially or wholly, by Newco I or a subsidiary of Newco
I  (collectively,  the  "Restricted  Area"),  any services  (other than services
included in the practice of medicine) related to (i) the operating of centers or
facilities that provide Refractive Surgery,  (ii) the manufacture,  maintenance,
refurbishing,  repair, sale, or leasing of any equipment related to or necessary
for the operating of centers or facilities that provide Refractive  Surgery,  or
(iii) providing any management services, training or consulting services related
to any of the activities described in (i) or (ii);

                  (b) Except through Newco I or its  subsidiaries,  or Newco II,
directly  or  indirectly  provide,  anywhere  within the  Restricted  Area,  (i)
facilities,  equipment  and  non-physician  personnel  for  the  performance  by
physicians of Refractive Surgery, (ii) the marketing,  scheduling and management
of Refractive Surgery (but excluding,  with respect to either Barnet or Dulaney,
marketing,  scheduling  and  management  of patients for  treatment by Barnet or
Dulaney, respectively),  (iii) the credentialing and scheduling of physicians to
perform  Refractive  Surgery and (iv) the billing,  collecting or accounting for
the use of any such facilities, equipment or non-physician personnel.

          (c)  Directly  or  indirectly  request  or advise  any  person,  firm,
     physician,  corporation or other entity having a business relationship with
     Newco I or any of its subsidiaries,  Prime, each Seller or any affiliate or
     related entity of any of them, to withdraw, curtail, or cancel its business
     with such person or entity; or

          (d) Directly or indirectly  hire any employee of Newco I or any of its
     subsidiaries,  Prime,  any Seller or any affiliate or related entity of any
     of them,  or induce or attempt to influence  any employee of Newco I or any
     of its  subsidiaries,  Prime,  any Seller or any such  affiliate or related
     entity to terminate his or her employment with such person or entity.

          9.5  Exclusivity.  Each of the parties hereto  acknowledges and agrees
     that any  acquisition  or  development  of a Target Center by Prime,  PMSI,
     Newco II or a Seller  through  an entity not owned  (wholly  or  partially,
     directly or  indirectly)  by Newco I shall be subject to the  provisions of
     Section 9.4,  regardless  of whether such  acquisition  or  development  is
     contemplated  by or  provided  for  in  the  provisions  of  ARTICLE  VIII.
     -----------

          9.6  Agreement.  Each of Prime,  PMSI and each Seller has reviewed and
     carefully  considered  the  provisions of Sections 9.3 and 9.4 and,  having
     done so, agrees that the restrictions applicable to it as set forth therein
     (a) are fair and  reasonable  with  respect  to time,  geographic  area and
     scope,  (b) are not  unduly  burdensome  to  them,  and (c) are  reasonably
     required for the  protection of the  interests of the other parties  hereto
     for whose benefit such restrictions were agreed upon. ---------

         9.7  Remedies.  Each of  Prime,  PMSI and  each  Seller  agrees  that a
violation on its part of any  applicable  covenant  contained in Sections 9.3 or
9.4 will cause the other parties hereto for whose benefit such restrictions were
agreed upon  irreparable  damage for which remedies at law may be  insufficient,
and for that  reason,  it agrees that the other  parties  shall be entitled as a
matter  of right to  equitable  remedies,  including  specific  performance  and
injunctive relief,  therefor.  The right to specific  performance and injunctive
relief shall be cumulative and in addition to whatever other remedies, at law or
in equity, that the other parties may have, including, specifically, recovery of
additional damages.

         9.8      Special Options to Sell or Acquire Interests In Newco I.

                  (a)  Option  to Sell.  Upon the  expiration  of five (5) years
immediately  following  the  Closing  Date,  if no  Seller  is in breach of this
Agreement or any other Transaction Document,  all or any of the Sellers shall at
any time, and from time to time, be entitled to require that Prime purchase from
such  Seller(s) up to a maximum  twenty  percent (20%) interest in Newco I (when
aggregated  with all other purchases  pursuant to this Section),  upon the terms
and conditions  hereinafter set forth, by giving written notice of such election
to Prime.

          (b) No Further  Obligation.  The  Sellers  acknowledge  and agree that
     Prime shall be under no  obligation to notify any Seller of the exercise by
     another Seller of rights under this Section,  and that Prime may not, under
     any  circumstances,  be required to purchase more than an aggregate  twenty
     percent (20%)  interest in Newco I (considering  all purchases  pursuant to
     this Section  together),  regardless of whether one Seller disposes of more
     or less of an interest in Newco I under this ---------------------  Section
     than another Seller.

          (c) Purchase  Price.  The purchase price for any interest  transferred
     pursuant to this  Section  shall,  in the absence of an  agreement on price
     between  Prime and the  applicable  Seller(s),  be  determined  as follows:
     --------------

          (i) If the exercise of the option hereunder is after the expiration of
     such  ninety  (90) day  period,  then the  purchase  price must be mutually
     agreed upon by the applicable Seller(s) and Prime.

                           (ii)  If the  exercise  of the  option  hereunder  is
         within the ninety (90) day period immediately  following the expiration
         of the five (5) year period  described  in Section  9.8(a),  then Prime
         shall select a certified business appraiser (that is a member of either
         the  American  Society  of  Appraisers  or the  Institute  of  Business
         Appraisers)  to value the interest  being  transferred.  If the selling
         Seller(s) under this Section do not agree with the value  determined by
         Prime's appraiser,  such Seller(s) may, at their own expense,  select a
         second  appraiser  that is a member of one or both of the  above  named
         professional organizations to value the interest being transferred.  If
         the two  appraisers  cannot  agree on the value of the  interest  being
         transferred, the two appraisers shall mutually select a third appraiser
         (that meets the above described  membership  requirements) to value the
         interest  being  transferred  together  with the first two  appraisers,
         based on a  majority  vote.  Any  valuation  determined  by such  third
         appraiser shall be final,  binding and conclusive.  The expense of such
         third  appraiser  shall be paid by the  selling  Seller(s),  unless the
         appraised  value  ultimately  determined is more than ten percent (10%)
         greater than the value  determined by Prime's  original  appraiser,  in
         which event Prime shall bear the entire cost of the third appraiser. If
         the exercise of the option  hereunder is after the  expiration  of such
         ninety (90) day period, then the purchase price must be mutually agreed
         upon by the applicable Seller(s) and Prime.

                  (d) Such purchase price shall be paid in immediately available
funds at the closing of the transfer  pursuant to this  Section.  The closing of
any purchase and sale pursuant to this Section shall take place at the principal
office of Prime or such  other  place  designated  by Prime  and the  applicable
Seller(s), on the thirtieth day (or if such thirtieth day is not a business day,
the  next  business  day  following  the  thirtieth  day)  following  the  final
determination  of a purchase price under  subsection (c) above. At such closing,
Seller  shall  execute  all  documents  and take such  other  actions  as may be
reasonably necessary to deliver to Prime title to the interest transferred, free
and clear of all liens,  claims,  encumbrances  or  restrictions  of any kind or
nature whatsoever,  except those established in the Organizational Documents and
other governing documents of Newco I.

          (e)  Exceptions.  Notwithstanding  the  foregoing  provisions  of this
     Section 9.8, Prime shall not be obligated to purchase any interest in Newco
     I pursuant to this Section if Prime is unable to obtain  financing for such
     purchase from a third party upon reasonable  market terms,  after Prime and
     PMSI  have  exercised  commercially   reasonable  efforts  to  obtain  such
     financing. ----------

          9.9 Obligation to Extinguish  Debt.  Each of BDEC,  Barnet and Dulaney
     agrees that it or he will take all  necessary  action,  including,  without
     limitation,  execute  any  documents  and  pay  any  amounts,  that  may be
     necessary to cause the lien on certain of the Assets in favor of Camel Back
     Bank  (described  more fully on Schedule 1.4 attached  hereto) to be fully,
     unconditionally and irrevocably released on or prior to September 30, 1999.
     ----------------------------- ------------

          9.10 Notice of Certain Transfers. Without in any manner restricting or
     modifying any prohibition on the sale of BDEC ownership interests by any of
     the owners of BDEC,  each of the Sellers  agrees that it must notify  Prime
     and Newco II in writing  within  three (3) days of learning of any transfer
     of BDEC ownership interests. ---------------------------

          9.11 Fiscal Years of Newco I and Newco II. Each of the parties to this
     Agreement hereby agrees to vote its interests, if any, in Newco I and Newco
     II,  and to vote in its  capacity  as a manager  of Newco I or Newco II, if
     applicable,  to cause the  fiscal  years of each of Newco I and Newco II to
     end annually on December 31. ------------------------------------

         9.12  Right of Offset.  Each  Seller  agrees  that Newco I and Newco II
shall each have  rights of offset  against  distributions  to either BDEC and/or
LASIK in respect of any ownership  interest either may have in either Newco I or
Newco II at any time following the Closing,  for any and all debts,  obligations
or  liabilities  that any Seller may have to Prime or PMSI,  including,  without
limitation,  any liability arising out of or relating to such Seller's indemnity
obligations under this Agreement or any Transaction Document. Each Seller hereby
authorizes  and directs  Newco I and Newco II, and appoints  each of Newco I and
Newco II as its  attorney in fact,  to withhold  and pay such offset  amounts to
Prime and to take all other  actions  necessary  to make such  payment.  Each of
Newco I and Newco II hereby  agrees to  promptly  remit any and all such  offset
amounts to Prime upon request.

                                                     ARTICLE X

                                                   Miscellaneous

          10.1 Collateral  Agreements,  Amendments,  and Waivers. This Agreement
     (together with the Transaction  Documents)  supersedes all prior documents,
     understandings,   and  agreements,   oral  or  written,  relating  to  this
     transaction and constitutes the entire understanding among the parties with
     respect to the subject matter hereof.  Any modification or amendment to, or
     waiver of, any  provision of this  Agreement (or any  Transaction  Document
     unless  otherwise   expressly   provided  therein)  may  be  made  only  by
     ----------------------------------------------  an  instrument  in  writing
     executed by each party thereto.

          10.2  Successors and Assigns.  No party's rights or obligations  under
     this  Agreement may be assigned  without the prior  written  consent of all
     parties  hereto,  except  that Prime may assign its rights and  obligations
     hereunder to any entity, more than fifty percent (50%) of the voting equity
     ownership interests of which is at the time owned,  directly or indirectly,
     by PMSI.  Any  assignment in violation of the  foregoing  shall be null and
     void.    Subject   to   the   preceding    sentences   of   this   Section,
     ----------------------  the  provisions  of  this  Agreement  (and,  unless
     otherwise expressly provided therein, of any Transaction Document) shall be
     binding  upon and inure to the  benefit  of the  parties  hereto  and their
     respective heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.  Up to $3,000 of the costs and expenses  incurred
by Prime and associated  specifically  with the formation and  documentation  of
Newco I and Newco  II,  including  legal  fees and  expenses  for  drafting  the
Organizational Documents, shall be paid to Prime, or reimbursed, by Newco II.

          10.4 Severability.  This Agreement (including, without limitation, the
     provisions  contained  in Section  9.3 and  Section  9.4) is intended to be
     performed in  accordance  with,  and only to the extent  permitted  by, all
     applicable laws,  ordinances,  rules and  regulations.  If any provision of
     this Agreement,  or the application  thereof to any person or circumstance,
     shall, for any reason and to any extent,  be invalid or  unenforceable  but
     the extent of the  invalidity  or  unenforceability  does not  ------------
     destroy the basis of the bargain  between the parties as contained  herein,
     the remainder of this  Agreement and the  application  of such provision to
     other persons or circumstances  shall not be effected  thereby,  but rather
     shall be enforced to the fullest extent permitted by law.

          10.5  Waiver.  No  failure  or  delay  on the  part  of any  party  in
     exercising  any right,  power,  or privilege  hereunder or under any of the
     documents  delivered in connection  with this Agreement  shall operate as a
     waiver of such right, power, or privilege;  nor shall any single or partial
     exercise of any such  right,  power,  or  privilege  preclude  any other or
     future  exercise  thereof  or the  exercise  of any other  right,  power or
     privilege. ------

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise  expressly provided therein,  under Transaction
Document)  shall be given in  writing  and  shall be  deemed  received  (a) when
delivered  personally or by courier service to the relevant party at its address
as set forth below or (b) if sent by mail,  on the third day  following the date
when deposited in the United States mail,  certified or registered mail, postage
prepaid, to the relevant party at its address indicated below:

Prime, Newco I and  Prime Medical Operating, Inc., Prime/BDR Acquisition, L.L.C.
Newco II:                          and Prime/BDEC Acquisition, L.L.C.
                                   1301 Capital of Texas Highway
                                   Suite C-300
                                   Austin, Texas  78746
                                   Attention:  President

with a copy to:                     Mr. Timothy L. LaFrey
                                    Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                    816 Congress Avenue, Suite 1900
                                    Austin, Texas  78701

Sellers:                            Barnet Dulaney Eye Center, P.L.L.C., LASIK
                                    Investors, L.L.C., David D. Dulaney, M.D.,
                                    Ronald W. Barnet, M.D., and Mark Rosenberg
                                    4800 North 22nd Street
                                    Phoenix, AZ  85016


with a copy to:                                      Mr. Bert L. Campbell
                                    Vinson & Elkins, L.L.P.
                                    2300 First City Tower
                                    1001 Fannin Street
                                    Houston, Texas  77002


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

     10.7 Survival of Agreement.  Regardless  of any  investigation  at any time
made by or on  behalf of any party  hereto or of any  information  any party may
have  in  respect  thereof,  all of the  provisions  of this  Agreement  and the
Transaction Documents shall survive the Closing.

     10.8 Further Assurances. At, and from time to time after, the Closing, each
party shall, at the request of another party, but without further consideration,
execute  and  deliver  such  other   instruments  of   conveyance,   assignment,
assumption,  transfer  and delivery and take such other action as such party may
reasonably  request in order more  effectively  to consummate  the  transactions
contemplated hereby.

         10.9 Construction,  Knowledge and Materiality.  This Agreement and each
Transaction  Document  shall be construed  without regard to the identity of the
person who drafted the various  provisions of the same. Each and every provision
of this Agreement and each Transaction Document shall be construed as though all
of the parties participated  equally in the drafting of the same.  Consequently,
the parties  acknowledge and agree that any rule of construction that a document
is to be construed  against the drafting party shall not be applicable either to
this  Agreement or any  Transaction  Document.  For purposes of this  Agreement,
whenever there are references to "material" or "materially," such terms shall be
deemed to mean an economic impact exceeding  $25,000 with respect to the fact or
matter being referred to or described. As used herein, "day" or "days" refers to
calendar  days  unless  otherwise  specified  in each  instance.  When  the term
"knowledge" is used in this  Agreement in reference to (i) Prime,  it shall mean
such items as are  within the actual  knowledge  of Ken  Shifrin,  Joe  Jenkins,
Cheryl  Williams  and John  Hedrick  and (ii) BDEC or LASIK,  it shall mean such
items as are within the actual knowledge of Pinkert, Perkins, Dulaney, Barnet or
Rosenberg.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

     10.11  Arbitration.  Any  controversy  between the parties  regarding  this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to arbitration by either party. The arbitration  proceedings  shall be
conducted by a single arbitrator pursuant to the Commercial Arbitration Rules of
the American  Arbitration  Association.  The  arbitration  shall be conducted in
Dallas,  Texas and the  arbitrator  shall have the right to award actual damages
and  attorney  fees and costs,  but shall not have the right to award  punitive,
exemplary or consequential damages against either party.

     10.12 Counterparts. This Agreement may be executed in several counterparts,
each of which shall  constitute  an  original  and all of which  together  shall
constitute  one and the same  instrument.  Any party  hereto  may  execute  this
Agreement by signing any one counterpart.

                                             [Signature pages follow]




<PAGE>



                                                 SIGNATURE PAGE TO
                                              CONTRIBUTION AGREEMENT


         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.


PRIME:                                      PRIME MEDICAL OPERATING, INC.


                                            By:/s/ Kenneth Shifrin

                                            Printed Name:Ken Shifrin

                                            Title:Chairman of the Board



BDEC:                                       BARNET DULANEY EYE CENTER, P.L.L.C.


                                            By:/s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                            By:/s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager



LASIK:                                      LASIK INVESTORS, L.L.C.


                                            By:/s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                            By: /s/ David D. Dulaney, M.D.
                                                David D. Dulaney, M.D., manager


NEWCO I:                                    PRIME/BDR ACQUISITION, L.L.C.

                                            By:
                                               LASIK Investors, L.L.C.. - Member


                                            By:  /s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                            By:  /s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager


                                            By:
                                          Prime Medical Operating, Inc. - Member


                                            By: /s/ Cheryl Williams
                                            Printed Name: Cheryl Williams

                                            Title: Treasurer

NEWCO II:                                   PRIME/BDEC ACQUISITION, L.L.C.

                                            By:
                                    Barnet Dulaney Eye Center, P.L.L.C. - Member


                                            By: /s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                            By:  /s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager


                                            By:
                                          Prime Medical Operating, Inc. - Member


                                            By: /s/ Cheryl Williams
                                            Printed Name: Cheryl Williams

                                            Title: Treasurer



<PAGE>




DULANEY:                                    /s/ David D. Dulaney, M.D.
                                            David D. Dulaney, M.D.

BARNET:                                     /s/ Ronald W. Barnet, M.D.
                                            Ronald W. Barnet, M.D.

ROSENBERG:                                   /s/ Mark Rosenberg
                                             Mark Rosenberg


PMSI:                                        PRIME MEDICAL SERVICES, INC.


                                            By:  /s/ Cheryl Williams

                                            Printed Name:Cheryl Williams

                                            Title: Treasurer





<PAGE>


                                                 TABLE OF EXHIBITS


Exhibit A                  Form of Primary Warrants

Exhibit B                  Form of Organizational Documents of Newco I

Exhibit C                  Form of Organizational Documents of Newco II

Exhibit D                  Form of Assignment and Assumption Agreement

Exhibit E                  PMSI Financial Statements

Exhibit F                  BDEC Financial Statements

Exhibits G1
     to G5                 Credit Documents

Exhibit H                  LASIK Ownership Interest Transfer Restriction
                           Agreement

Exhibit I                  Collocation Agreement

Exhibit J                  Consulting Agreement

<PAGE>
                                    EXHIBIT-A

                               WARRANT CERTIFICATE

THE WARRANT  REPRESENTED BY THIS  CERTIFICATE AND THE COMMON STOCK ISSUABLE UPON
THE EXERCISE HEREOF HAVE NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED,  OR APPLICABLE  STATE SECURITIES LAWS, AND MAY NOT BE TRANSFERRED OR
RESOLD WITHOUT  REGISTRATION UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS
UNLESS AN EXEMPTION FROM REGISTRATION IS THEN AVAILABLE.

                        WARRANT TO PURCHASE COMMON STOCK

                                       OF

                          PRIME MEDICAL SERVICES, INC.

                             Date: ________________

         This is to certify that, for value received, Barnet Dulaney Eye Center,
P.L.L.C.  (the  "Holder") is entitled to purchase,  subject to the provisions of
this Warrant (including,  without limitation,  the vesting provisions of Section
10), from Prime Medical  Services,  Inc., a Texas  corporation  (the "Company"),
Forty Four Thousand Thirty Five (44,035)  shares of the Company's  common stock,
$.01 par value (such class of stock  being  referred to herein as the  "Stock"),
for $9.4875 per share (the "Exercise Price"). This Warrant is issued pursuant to
that  certain  Contribution  Agreement  (the  "Contribution  Agreement"),  dated
effective September 1, 1999, by and among the Company,  Prime Medical Operating,
Inc., a Delaware  corporation,  the Holder,  Prime/BDEC  Acquisition,  L.L.C., a
Delaware limited liability company,  Prime/BDR  Acquisition,  L.L.C., a Delaware
limited liability company, LASIK Investors, L.L.C., a Delaware limited liability
company, David D. Dulaney, M.D., Ronald W. Barnet, M.D., and Mark Rosenberg. The
number of shares of Stock to be received  upon the  exercise of this Warrant and
the Exercise Price shall be adjusted from time to time as hereinafter set forth.
The  shares  of Stock or other  securities  or  property  deliverable  upon such
exercise,  as adjusted from time to time, are hereinafter  sometimes referred to
as "Warrant Shares." Unless the context otherwise  requires,  the term "Warrant"
or  "Warrants"  as used herein  includes  this Warrant and any other  Warrant or
Warrants which may be issued pursuant to the provisions of this Warrant, whether
upon transfer, assignment, partial exercise, divisions,  combinations,  exchange
or otherwise,  and the term "the Holder"  includes any registered  transferee or
transferees or registered  assignee or assignees of the Holder, who in each case
shall be subject to the provisions of this Warrant, and when used with reference
to Warrant Shares, means the holder or holders of such Warrant Shares.

         SECTION  1.  Exercise  of  Warrant.  Subject to the  provisions  hereof
(including,  without  limitation,  the vesting  provisions  of Section 10), this
Warrant  may be  exercised  in whole or in part at any time or from time to time
during the period commencing on _______________  (the  "Commencement  Date") and
ending 5:00 P.M.,  Central  Standard Time, on  _______________  (the "Expiration
Date"),  by presentation and surrender to the Company at its principal office of
this Warrant and the Purchase Form,  attached hereto as Exhibit A, duly executed
and  accompanied  by  payment  of the  Exercise  Price for the number of Warrant
Shares  specified in such form.  The Exercise  Price may be paid at the Holder's
election  either (i) by cash,  certified or official  bank check  payable to the
order of the  Company,  or (ii) by  surrender of Warrants  ("Net  Issuance")  as
determined below. If the Holder elects the Net Issuance method, the Company will
issue that number of Warrant Shares  determined by (a)  subtracting the Exercise
Price from the Fair Market Value,  (b) multiplying such difference by the number
of shares of Warrant Shares requested to be exercised under this Warrant and (c)
dividing such product by the Fair Market Value.  As used in this Warrant,  "Fair
Market  Value" shall mean the per share price of the Warrant  Shares at the time
of exercise,  as  determined  by averaging the closing price per share quoted by
NASDAQ on the five trading days immediately  preceding the date of Exercise.  If
this  Warrant is  exercised  in part only,  the Company  shall,  promptly  after
presentation  of this  Warrant  upon such  exercise,  execute  and deliver a new
Warrant  evidencing  the rights of the Holder thereof to purchase the balance of
the Warrant Shares  purchasable  hereunder upon the same terms and conditions as
herein set forth.

         SECTION 2. Reservation of Shares.  The Company shall at all times after
the Commencement  Date and until expiration of this Warrant reserve for issuance
and delivery upon exercise of this Warrant the number of Warrant Shares as shall
be required for issuance and delivery upon exercise of this Warrant.

         SECTION  3.   Fractional   Shares.   No  fractional   shares  or  scrip
representing  fractional  shares  shall  be  issued  upon the  exercise  of this
Warrant.  With  respect to any  fraction  of a share  called  for upon  exercise
hereof,  the  Company  shall pay to the  Holder an amount in cash  equal to such
fraction  multiplied  by the  current  market  value of such  fractional  share,
determined as follows:

                  (a) if the Stock is listed on a national  securities  exchange
         or admitted to unlisted trading privileges  thereon,  the current value
         shall be the last  reported sale price of the Stock on such exchange on
         the last business day prior to the date of exercise of this Warrant, or
         if no such sale is made on such day,  such  price of the Stock for such
         immediately preceding day as such a sale occurred on such exchange; or

                  (b) if the  Stock is not so  listed or  admitted  to  unlisted
         trading  privileges,  the  current  value shall be the mean of the last
         reported  high and low  prices of the Stock  reported  by a  comparable
         exchange system  selected by the Board of Directors of the Company,  on
         the  last  business  day  prior  to the  date of the  exercise  of this
         Warrant; or

                  (c) if the Stock is not listed or admitted to unlisted trading
         privileges,  and bid and asked prices are not so reported,  the current
         value shall be an amount,  not less than book value per share of Stock,
         determined in such reasonable  manner as may be prescribed by the Board
         of Directors of the Company.

         SECTION 4.        Transfer, Exchange, Assignment or Loss of Warrant.

         4.1 Neither this  Warrant,  nor any rights or interest  herein,  may be
assigned,  transferred or encumbered,  in whole or in part,  without the express
written  consent  of the  Company  in each  instance,  and upon  receipt of such
consent may only be assigned,  transferred  or encumbered as provided  herein so
long as such  assignment  or transfer is in  accordance  with and subject to the
provisions  of the  Securities  Act of  1933,  as  amended,  and the  rules  and
regulations  promulgated  thereunder  (said Act and such  rules and  Regulations
being  hereinafter  collectively  referred  to as  the  "Securities  Act").  Any
purported transfer or assignment made other than in accordance with this Section
4 shall be null and void and of no force and effect.

         4.2 Any assignment  permitted  hereunder  shall be made by surrender of
this  Warrant  to the  Company  at its  principal  office,  with  any  requested
assignment  form duly executed and funds  sufficient to pay any transfer tax. In
such event the Company shall, without charge,  execute and deliver a new Warrant
in the name of the assignee named in such instrument of assignment and designate
the assignee as the registered  holder on the Company's records and this Warrant
shall promptly be canceled.

         4.3 Upon receipt by the Company of evidence  satisfactory  to it of the
loss,  theft,  destruction  or mutilation  of this Warrant,  and (in the case of
loss, theft or destruction) of reasonably  satisfactory  indemnification  to the
Company  or (in the  case  of  mutilation)  presentation  of  this  Warrant  for
surrender and  cancellation,  the Company will execute and deliver a new Warrant
of like tenor and date and any such lost, stolen, destroyed or mutilated Warrant
shall thereupon become void.

SECTION 5.  Adjustment in the Number of Warrant Shares  Purchasable and Exercise
Price.

         5.1 The  number  of  shares of Stock  for  which  this  Warrant  may be
exercised shall be subject to adjustment as follows:

                  (a) in the event there is a subdivision  or combination of the
         outstanding  shares of Stock into a larger or smaller number of shares,
         the number of shares of Stock for which this  Warrant may be  exercised
         shall be increased or reduced in the same proportion as the increase or
         decrease in the outstanding shares of Stock;

                  (b) if the  Company  declares a dividend  on Stock  payable in
         Stock or  securities  convertible  into Stock,  the number of shares of
         Stock for which this Warrant may be exercised shall be increased, as of
         the  record  date for  determining  which  holders  of  Stock  shall be
         entitled to receive such dividend, in proportion to the increase in the
         number of outstanding shares of Stock as a result of such dividend;

                  (c) if the Company  decides to offer  rights to all holders of
         Stock which entitle them to subscribe to additional Stock or securities
         convertible  into Stock,  the Company shall give written  notice of any
         such proposed rights offering to the Holder at least fifteen days prior
         to the  proposed  record date in order to permit the Holder to exercise
         this  Warrant  on  or  before  such  record  date.  There  shall  be no
         adjustment  in the number of shares of Stock for which this Warrant may
         be exercised or the Exercise Price by virtue of such rights offering or
         by  virtue  of any  sale of any  class  of  securities  of the  Company
         pursuant to such rights offering.

         5.2 In the event at any time prior to the expiration of this Warrant of
any reorganization or reclassification of the outstanding shares of Stock (other
than a change in par value, or from no par value to par value, or from par value
to no par value,  or as a result of a subdivision  or  combination),  the Holder
shall have the right,  but not the  obligation,  to exercise this Warrant.  Upon
such  exercise,  Holder shall have the right to receive the same kind and number
of shares of stock and other  securities,  cash or other  property as would have
been distributed to the Holder upon such reorganization or reclassification  had
Holder  exercised  this  Warrant  immediately  prior to such  reorganization  or
reclassification.  The Holder shall pay upon such  exercise  the Exercise  Price
that otherwise would have been payable pursuant to the terms of this Warrant. If
any such  reorganization or  reclassification  results in a cash distribution in
excess of the  Exercise  Price  provided  by this  Warrant,  the Holder  may, at
Holder's  option,  exercise this Warrant  without making payment of the Exercise
Price, and in such case the Company shall, upon distribution to Holder, consider
the  Exercise  Price to have been  paid in full,  and in  making  settlement  to
Holder,  shall  deduct an amount  equal to the  Exercise  Price  from the amount
payable to the Holder.

         5.3 If the Company  shall,  at any time prior to the expiration of this
Warrant,  dissolve,  liquidate or wind up its affairs, the Holder shall have the
right,  but not the  obligation,  to exercise this  Warrant.  Upon such exercise
Holder  shall  have the right to  receive,  in lieu of the  shares of Stock that
Holder  otherwise would have been entitled to receive,  the same kind and amount
of assets as would have been issued, distributed or paid to Holder upon any such
dissolution,  liquidation or winding up with respect to such shares of Stock had
Holder  been the  holder  of  record of such  shares  of Stock  receivable  upon
exercise of this Warrant on the date for  determining  those entitled to receive
any such distribution. If any dissolution,  liquidation or winding up results in
any cash  distribution  in excess of the  Exercise  Price  provided  for by this
Warrant,  Holder may, at Holder's  option,  exercise this Warrant without making
payment  of the  Exercise  Price and,  in such case,  the  Company  shall,  upon
distribution  to Holder,  consider the Exercise Price to have been paid in full,
and in making  settlement to Holder shall deduct an amount equal to the Exercise
Price from the amount payable to Holder.

         5.4 In the event  that,  at any time  prior to the  expiration  of this
Warrant,  the Company is merged into or  consolidated  with another  corporation
under circumstances where the Company is not the surviving corporation,  or more
than 50 percent of the outstanding voting securities of the Company are owned by
another  corporation  as a result of such merger or  consolidation,  then at the
election of the Board of Directors of the Company (i) the successor entity shall
assume the Company's  obligations  hereunder and Holder shall be entitled,  upon
exercise of this  Warrant,  to receive in lieu of shares of Stock shares of such
stock or other securities as the holders of shares of Stock received pursuant to
the terms of the merger or consolidation or (ii) this Warrant may be canceled by
the Board of  Directors  of the  Company  as of the  effective  date of any such
merger or consolidation,  provided that (x) notice of such cancellation shall be
given to Holder, and (y) Holder shall have the right to exercise this Warrant in
full during a thirty (30) day period preceding the effective date of such merger
or consolidation.

         5.5 The Company may retain a firm of independent  public accountants of
recognized standing (who may be any such firm regularly employed by the Company)
to make any computation  required under this Section 5, and a certificate signed
by such firm shall be conclusive  evidence of the correctness of any computation
made under this Section.

         5.6  Whenever  the  number  of  shares  of Stock  purchasable  upon the
exercise of this  Warrant is adjusted as herein  provided,  the  Exercise  Price
shall be adjusted by multiplying the applicable Exercise Price immediately prior
to such adjustment by a fraction,  the numerator of which shall be the number of
shares of Stock  purchasable upon exercise of this Warrant  immediately prior to
such  adjustment  and the  denominator of which shall be the number of shares of
Stock purchasable immediately after such adjustment.

         SECTION 6. Officer's Certificate. Whenever the number of Warrant Shares
or the Exercise Price shall be adjusted as required by the provisions of Section
5 hereof, the Company forthwith shall file in the custody of its secretary or an
assistant  secretary,  at its  principal  office,  a  certificate  of the  chief
executive  officer of the  Company  setting  forth the number and kind of shares
purchasable, as so adjusted, stating that such adjustments in the number or kind
of shares or other  securities  conform to the requirements of Section 5 of this
Warrant,  and setting forth a brief  statement of the facts  accounting for such
adjustments.  Promptly  after  receipt of such  certificate,  the  Company  will
deliver,  by first-class mail,  postage prepaid,  a brief summary thereof (to be
supplied by the Company) to the Holder;  provided however,  that failure to file
or to give any notice  required under this  Subsection,  or any defect  therein,
shall not affect the legality or validity of any such adjustments  under Section
5. Each such  officer's  certificate  shall be made  available at all reasonable
times during reasonable hours for inspection by Holder.

         SECTION 7.  Cancellation  of Warrant.  This  Warrant may be revoked and
cancelled by the Company upon (i) the occurrence of certain events  specified in
the Contribution  Agreement,  (ii) any breach,  or threatened  breach by BDEC or
Holder of the Contribution  Agreement or any Transaction Document (as defined in
the Contribution Agreement) to which either BDEC or Holder is a party, (iii) any
breach or threatened breach by BDEC or Holder of any other contract or agreement
entered  into at any time by BDEC or Holder  and to which the  Company or any of
the Company's  subsidiaries or affiliates is a party or named  beneficiary,  and
(iv) upon any transfer or  encumbrance  or attempted  transfer or encumbrance by
Holder of this Warrant or any rights  hereunder or interest  herein in violation
of the provisions of Section 4 hereof.

         SECTION  8.  Notice  to  Holder.  So  long  as this  Warrant  shall  be
outstanding,  (i) if the Company shall pay any dividend or make any distribution
upon the Stock  otherwise than in cash or (ii) if the Company shall offer to the
holders of Stock for subscription or purchase by them any shares of any class or
any other  rights or (iii) if there shall be any capital  reorganization  of the
Company,  reclassification of the capital stock of the Company, consolidation or
merger of the Company with or into another corporation,  sale, lease or transfer
of all or  substantially  all of the  property  and  assets of the  Company,  or
voluntary or involuntary dissolution,  liquidation or winding up of the Company,
then in any such event,  the Company shall cause to be mailed by certified  mail
to Holder, at least twenty (20) days prior to the relevant date described below,
a notice  containing a brief  description of the proposed action and stating the
date or  expected  date on which a record is to be taken for the purpose of such
dividend,  distribution  or rights,  or such  reclassification,  reorganization,
consolidation,  merger, conveyance, lease or transfer, dissolution,  liquidation
or winding up and the date or expected  date as of which the holders of Stock of
record  shall be entitled to exchange  their shares of Stock for  securities  or
other property deliverable upon such event.

         SECTION 9. Warrant Certificate Holder Not Deemed a Stockholder.  Holder
shall not, solely because of holding the warrant,  be entitled to vote,  receive
dividends  or be  deemed  the  holder of Stock or any  other  securities  of the
Company which may at any time be issuable on the exercise of the Warrant for any
purpose  whatsoever,  nor shall anything contained herein be construed to confer
upon the Holder, as such, any of the rights of stockholder of the Company or any
right to vote for the  election of  directors  or upon any matter  submitted  to
stockholders  at any  time  thereof,  or to  give  or  withhold  consent  to any
corporate  action  (whether  upon  any  recapitalization,   issuance  of  stock,
reclassification  of  stock,  change  of par  value or change of stock to no par
value,  consolidation,  merger conveyance or otherwise), or to receive notice of
meetings or other actions affecting  stockholders (except as provided in Section
8 hereof),  or to receive dividend or subscription  rights, or otherwise,  until
such  Warrant  Certificate  shall have been  exercised  in  accordance  with the
provisions hereof and the Warrant Shares shall have been issued.

         SECTION 10. Vesting. Assuming Holder complies with all of the terms and
conditions  contained in this Warrant, all of Holder's rights under this Warrant
(including, without limitation, Holder's rights to acquire common stock pursuant
to this  Warrant)  shall vest  twenty  five  percent  (25%)  upon each  one-year
anniversary of the date of this Warrant.

SECTION 11. Agreement of Holder.  The Holder, by accepting this Warrant consents
and agrees with

     (a) The Warrants are transferable on the registry books of the Company only
upon the terms and conditions set forth in this Warrant; and

                  (b) The  Company  may deem and treat the  person in whose name
         the  Warrant  is  registered  as the  absolute  owner  of  the  Warrant
         (notwithstanding  any notation of ownership  or other  writing  thereon
         made by anyone  other than the  Company or the  Warrant  Agent) for all
         purposes  whatever and the Company  shall not be affected by any notice
         to the contrary, except as set forth in Section 4 of this Warrant.

SECTION 12.  Governing  Law. This Warrant shall be construed in accordance  with
the laws of the  State of  Texas  applicable  to  contracts  executed  and to be
performed wholly within such state.

         SECTION 13.  Notice.  Notices and other  communications  to be given to
Holder  of the  Warrant  evidenced  hereby  shall  be  delivered  by  hand or by
first-class mail, postage prepaid, to Barnet Dulaney Eye Center,  P.L.L.C., 4800
North 22nd Street,  Phoenix,  Arizona  85016,  Attn:  President  (until  another
address is filed in writing by the Holder  with the  Company).  Notices or other
communications to the Company shall be deemed to have been sufficiently given if
delivered by hand or by first-class mail, postage prepaid to the Company at 1301
Capital of Texas  Highway,  Suite  C-300,  Austin,  Texas  78746,  or such other
address  as the  Company  shall  have  designated  by  written  notice  to  such
registered owner is herein  provided.  Notice by mail shall be deemed given when
deposited in the United States mail, postage prepaid, as herein provided.

         SECTION  14.  Successors.  All the  covenants  and  provisions  of this
Warrant by or for the benefit of the Company shall bind and inure to the benefit
of its  successors  and assigns  hereunder,  and all covenants and provisions of
this Warrant by or for the benefit of the Holder of this Warrant  shall bind and
inure to the benefit of the registered holder of the Warrants.

SECTION 15. Termination. This Warrant shall terminate as of the earliest of: (a)
the close of business on the Expiration Date, (b) the date upon which all rights
hereunder  shall have been  exercised  or redeemed or (c) upon its  cancellation
pursuant to Section 7 of this Warrant.

         SECTION  16.  Benefits  of this  Agreement.  Nothing  in  this  Warrant
Certificate  shall be construed to give to any person or corporation  other than
the Company, and its respective  successors and assigns hereunder and the Holder
of any legal or equitable right, remedy or claim hereunder, but shall be for the
sole and  exclusive  benefit of the Company and its  respective  successors  and
assigns hereunder and the Holder.

                            [Signature page follows]


<PAGE>




                                SIGNATURE PAGE TO

                               WARRANT CERTIFICATE

         IN WITNESS  WHEREOF,  the Company has  executed  this Warrant as of the
date set forth above.

                                     PRIME MEDICAL SERVICES, INC.

                                      By:  ___________________________________

                                      Printed Name:  ___________________________

                                      Title:  __________________________________


                                    EXHIBIT A

                                  PURCHASE FORM

TO:  Prime Medical Services, Inc., Secretary

(1) The  undersigned  Holder  hereby  elects to purchase  _______  shares of the
common  stock,  $.01 par value,  of Prime  Medical  Services,  Inc.,  a Delaware
corporation  ("PMSI"),  pursuant to the terms of the Warrant Agreement dated the
1st day of August,  1999 (the "Warrant  Agreement") between PMSI and the Holder,
and tenders  herewith  payment in full of the Exercise  Price (as defined in the
Warrant Agreement) for such shares of common stock using (check only one):

         [  ]  cash
         [  ]  certified check

         [  ]  Net Issuance Method (as defined in the Warrant Agreement)

(2) The undersigned also tenders herewith all applicable transfer taxes, if any,
using cash or certified check.

(3) Please issue a certificate or certificates  representing said shares of PMSI
common  stock  in the  name  of the  undersigned  or in  such  other  name as is
specified below.

- ---------------------------------
(Name)
- ---------------------------------
(Address)


HOLDER: _________________________

By: _________________________
Title: _________________________
Date: _________________________

<PAGE>

                                    EXHIBIT-B

                       LIMITED LIABILITY COMPANY AGREEMENT

                        OF PRIME/BDR ACQUISITION, L.L.C.
     Organized under the Delaware Limited Liability Company Act (the "Act").

                                   ARTICLE I.

                                NAME AND LOCATION

     Section 1.1. Name. The name of this limited  liability company is Prime/BDR
Acquisition, L.L.C. (the "Company").

         Section  1.2.  Members.  The  only  members  of the  Company  upon  the
execution of this Limited Liability Company Agreement (this  "Agreement")  shall
be Prime Medical Operating,  Inc, a Delaware  corporation  ("Prime"),  and LASIK
Investors L.L.C., a Delaware limited liability company  ("LASIK").  For purposes
of this  Agreement,  the "Members"  shall include such named members and any new
members admitted  pursuant to the terms of this Agreement,  but does not include
any person or entity who has ceased to be a member in the Company.

     Section 1.3. Principal Office. The principal office of the Company shall be
located in 1301 Capital of Texas Hwy., Suite C-300, Austin, Texas 78746-6550, or
such other location as may be selected by the Members.

     Section 1.4. Registered Agent and Address. The name of the registered agent
and the  address  of the  registered  office of the  Company as set forth in the
Certificate of Formation of the Company are:

                                            The Corporation Trust Company
                                            1209 Orange Street
                                            Wilmington, Delaware 19801

     Section 1.5.  Other  Offices.  Other offices and other  facilities  for the
transaction of business shall be located at such places as the Managers may from
time to time determine.

         Section 1.6  Contribution  Agreement.  The Company was initially formed
with a single member,  LASIK,  for the purpose of consummating  the transactions
contemplated by that certain Contribution Agreement dated effective September 1,
1999, by and among Prime, Prime Medical Services,  Inc., a Delaware  corporation
("PMSI"),  LASIK, Barnet Dulaney Eye Center,  P.L.L.C.,  an Arizona professional
limited  liability  company,  the Company,  Prime/BDEC  Acquisition,  L.L.C.,  a
Delaware limited liability  company,  David D. Dulaney,  M.D., Ronald W. Barnet,
M.D.,  and Mark  Rosenberg  (the  "Contribution  Agreement").  The parties  have
executed this Agreement upon  consummation of the  transactions  contemplated by
the  Contribution  Agreement.  This agreement  supercedes and replaces any prior
membership  agreement  or other  governing  or  organizational  document  of the
Company.

                                   ARTICLE II.

                                   MEMBERSHIP

     Section 2.1. Members' Interests.  The "Membership  Interest" of each Member
is set forth on Exhibit A.

     Section 2.2. Admission to Membership. The admission of new Members shall be
only by the unanimous  vote of the Members.  If new members are  admitted,  this
Agreement shall be amended to reflect each Member's revised Membership Interest.

     Section 2.3.  Property  Rights.  No Member shall have any right,  title, or
interest in any of the property or assets of the Company.

     Section  2.4.  Liability  of  Members.  No Member of the  Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment decree, or order of court.

         Section 2.5.  Transferability of Membership.  Except as provided below,
Membership  Interests in the Company are  transferable  only with the  unanimous
written  consent  of all  Members.  If such  unanimous  written  consent  is not
obtained when  required,  the  transferee  shall be entitled to receive only the
share of  profits  or other  compensation  by way of  income  and the  return of
contributions  to which  the  transferor  Member  otherwise  would be  entitled.
Notwithstanding  the  foregoing,  (i) the  Membership  Interests of Prime may be
freely  transferred,  without  consent,  to any  entity  that is then  owned  or
controlled, directly or indirectly, by PMSI (or its successor in interest), (ii)
the  Membership  Interests  of any  Member  may be freely  assigned,  pledged or
otherwise  transferred,  without  consent,  to  secure  any debt,  liability  or
obligation  owed to Prime by the  Company,  any Member or any entity  affiliated
with the  Company,  (iii) the  Membership  Interests of any Member may be freely
assigned,  pledged or otherwise  transferred,  without consent,  in favor of the
Lender(s)  under,  or by the  Lender(s)  as a result of the  enforcement  of any
security  interest arising pursuant to, that certain Senior Credit Facility (the
"Credit  Facility") of PMSI, (iv) the Membership  Interests of any Member may be
freely  transferred,  without  consent,  pursuant to and in accordance  with the
express terms and conditions of the Contribution Agreement,  and (iv) the pledge
by LASIK (pursuant to Section 6.3 of the Contribution Agreement) of its right to
receive  distributions  from the Company in respect of its  Membership  Interest
shall not be deemed to violate any provision of this Agreement..

         Section 2.6. Resignation of Members. A Member may not withdraw from the
Company except on the unanimous consent of the remaining  Members.  The terms of
the Members  withdrawal  shall be determined by agreement  between the remaining
Members and the withdrawing Member.

                                  ARTICLE III.

                                MEMBERS' MEETINGS

         Section  3.1.  Time and Place of Meeting.  All  meetings of the Members
shall be held at such  time and at such  place  within or  without  the State of
Delaware as shall be determined by the Managers.

         Section 3.2. Annual  Meetings.  In the absence of an earlier meeting at
such  time and place as the  Managers  shall  specify,  annual  meetings  of the
Members shall be held at the  principal  office of the Company on the date which
is thirty  (30) days after the end of the  Company's  fiscal year if not a legal
holiday,  and if a legal holiday,  then on the next full business day following,
at 10:00 a.m.,  at which  meeting the Members may transact  such business as may
properly be brought before the meeting.

     Section  3.3.  Special  Meetings.  Special  meetings  of the Members may be
called at any time by any Member.  Business transacted at special meetings shall
be confined to the purposes stated in the notice of the meeting.

         Section 3.4.  Notice.  Written or printed notice stating the place, day
and hour of any Members'  meeting,  and, in the case of a special  meeting,  the
purpose or purposes for which the meeting is called, shall be delivered not less
than ten (10) days nor more than thirty (30) days before the date of the special
meeting,  either  personally  or by mail,  by or at the  direction of the person
calling the meeting, to each Member entitled to vote at such meeting. If mailed,
such notice shall be deemed to be delivered three (3) days after it is deposited
in the United States mail,  postage prepaid,  to the Member at his address as it
appears on the records of the Company at the time of mailing.

         Section 3.5. Quorum. Members present in person or represented by proxy,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any meeting  shall  constitute  a quorum at all  meetings of the Members for the
transaction  of  business.  If,  however,  such  quorum  shall not be present or
represented at any meeting of the Members, the Members entitled to vote, present
in person or represented by proxy,  shall have power to adjourn the meeting from
time to time,  without notice other than  announcement  at the meeting,  until a
quorum shall be present or represented. When any adjourned meeting is reconvened
and a quorum shall be present or  represented,  any  business may be  transacted
which might have been  transacted at the meeting as originally  noticed.  Once a
quorum is constituted,  the Members present or represented by proxy at a meeting
may  continue  to  transact  business  until  adjournment,  notwithstanding  the
subsequent  withdrawal therefrom of such number of Members as to leave less than
a quorum.

         Section 3.6. Voting. When a quorum is present at any meeting,  the vote
of the Members, whether present or represented by proxy at such meeting, holding
more  than  fifty  percent  (50%) of the  total  votes  which may be cast at any
meeting shall be the act of the Members,  unless the vote of a different  number
is required by the Act, the  Certificate of Formation or this Limited  Liability
Company Agreement. Each Member shall be entitled to one vote for each percentage
point  represented by their  Membership  Interest.  Fractional  percentage point
interests shall be entitled to a corresponding fractional vote.

         Section  3.7.  Proxy.  Every  proxy must be  executed in writing by the
Member or by his duly authorized  attorney-in-fact,  and shall be filed with the
Secretary of the Company prior to or at the time of the meeting.  No proxy shall
be  valid  after  eleven  (11)  months  from the  date of its  execution  unless
otherwise  provided  therein.  Each proxy shall be  revocable  unless  expressly
provided therein to be irrevocable and unless otherwise made irrevocable by law.

         Section  3.8.  Action  by  Written  Consent.  Any  action  required  or
permitted  to be taken at any  meeting  of the  Members  may be taken  without a
meeting if a consent in  writing,  setting  forth the action so taken,  shall be
signed by all of the Members entitled to vote with respect to the subject matter
thereof,  and such  consent  shall have the same force and effect as a unanimous
vote of Members.

         Section 3.9. Meetings by Conference Telephone.  Members may participate
in and hold  meetings  of Members by means of  conference  telephone  or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

                                   ARTICLE IV.

                        MEMBERSHIP CAPITAL CONTRIBUTIONS

         Except  for  each  Member's  initial  capital   contribution   made  in
connection with the formation of the Company, no capital  contributions shall be
required  of any  Member  without  the  approval  of all the  Members  to  raise
additional capital, and only then proportionately as to each Member.

                                   ARTICLE V.

                             DISTRIBUTION TO MEMBERS

         The Company shall not  distribute (or allow to be  distributed)  to its
members,  with respect to their  respective  membership  interests,  any cash or
other  property  of the  Company  or its  subsidiaries  if,  at the  time of the
proposed   distribution,   any  amounts  (whether  principal  or  interest)  are
outstanding  under the Credit  Documents or the Target Center Lending  Documents
(as such terms are  defined in the  Contribution  Agreement).  Furthermore,  the
Company shall pay all  available  cash flow to Prime in payment of the Company's
outstanding obligations,  if any, under the Working Capital Line and Development
Facility (as such terms are defined in the Contribution Agreement), irrespective
of whether such payments exceed the minimum required  payments under the Working
Capital Line and Development Facility.  For purposes of allocating such payments
among any two or more of such  outstanding  obligations,  such payments shall be
allocated  pro rata,  based upon the  respective  balances of such  obligations,
unless (i) a greater  portion of the  payment is  required  to be paid  toward a
given  obligation in order to prevent a default with respect to that  obligation
(but only to the extent  necessary  to prevent  such a default)  or (ii)  eighty
percent (80%) of the managers of the Company elect to allocate the payments in a
different manner.

         Notwithstanding  the foregoing,  as long as no party other than PMSI or
Prime is in default under the  Contribution  Agreement or any other  Transaction
Document (as defined in the Contribution Agreement, but excluding,  however, the
Credit Documents and the Target Center Lending  Documents),  then, to the extent
that (but only to the extent that) the Company possesses the cash flow necessary
(in  the  reasonable  discretion  of a  majority  of its  managers)  to pay  its
liabilities in the ordinary course  consistent with past practices,  the Company
agrees to make  quarterly  estimates  of its taxable  income for the current tax
year  and,  if not  prohibited  by law,  distribute  quarterly  (the  "Quarterly
Distributions")  an amount that would cover the federal and state  income  taxes
required to be paid by its members with respect  such taxable  income,  based on
each member's then current proportionate interest in the Company,  assuming that
all members pay income taxes on the Company's  taxable  earnings at a rate equal
to the highest  effective  individual  tax rate in effect from time to time (the
"Assumed Tax Rate");  provided,  further,  that the Company shall  determine its
actual  taxable  income at the end of each taxable year and (A) if the Quarterly
Distributions  in a given year should  have been  higher  based on the amount of
actual taxable income for that year,  promptly  distribute the amounts necessary
to eliminate such  deficiency or (B) if the Quarterly  Distributions  in a given
year  should have been lower  based on the amount of actual  taxable  income for
that  year,  withhold  dollar  for  dollar  from the first  following  Quarterly
Distribution,  and then against  subsequent  Quarterly  Distributions  in a like
manner, the amounts necessary to eliminate such surplus.

         Subject to the foregoing,  the Managers shall determine,  in their sole
discretion,  the  amount  and  timing  of all  distributions  from the  Company.
Distributions  shall be  divided  among the  Members  in  accordance  with their
Membership Interests. Distributions in kind shall be made on the basis of agreed
value  as  determined  by the  Members.  In no  event  may  the  Company  make a
distribution  to  its  Members  if,  immediately  after  giving  effect  to  the
distribution,  all  liabilities  of the Company,  other than  liabilities to the
Members with respect to their  interests and  liabilities for which the recourse
of creditors is limited to  specified  property of the Company,  exceed the fair
value of the  Company's  assets;  except that the fair value of property that is
subject to  liability  for which  recourse of  creditors  is  limited,  shall be
included  in the  Company  assets  only to the extent that the fair value of the
property  exceeds that  liability.  Except as contemplated in this Article V, no
distributions  of cash or  other  assets  of the  Company  shall  be made to the
Members in their capacity as owners of the Company.

                                   ARTICLE VI.

              ALLOCATION OF NET PROFITS AND LOSSES FOR TAX PURPOSES

         For  accounting  and income tax  purposes,  all items of income,  gain,
loss,  deduction,  and  credit of the  Company  for any  taxable  year  shall be
allocated  among the  Members in  accordance  with their  respective  Membership
Interests,  except as may be otherwise  required by the Internal Revenue Code of
1986, as amended.

                                  ARTICLE VII.

                           DISSOLUTION AND WINDING UP

     Section 7.1.  Dissolution.  Notwithstanding  any  provision of the Act, the
Company shall be dissolved only upon the first of the following to occur:

               (a) Forty (40) years from the date of filing the  Certificate  of
          Formation of the Company;

               (b)  Written   consent  of  all  the  then  current   Members  to
          dissolution;

                  (c) The  bankruptcy of a Member,  unless there is at least one
         remaining Member and such Member or, if more than one remaining Member,
         all remaining Members agree to continue the Company and its business.

         Section 7.2.  Winding Up.  Unless the Company is continued  pursuant to
Section 7.1(c) of this Article VII., in the event of dissolution of the Company,
the Managers (excluding any Manager(s) holding office pursuant to designation by
a Member subject to bankruptcy  proceedings) shall wind up the Company's affairs
as soon  as  reasonably  practicable.  On the  winding  up of the  Company,  the
Managers  shall pay and/or  transfer the assets of the Company in the  following
order:

                    (a)  In  discharging   liabilities   (including  loans  from
               Members) and the expenses of concluding  the  Company's  affairs;
               and

                    (b) The  balance,  if any,  shall  be  divided  between  the
               Members in accordance with the Members' Membership Interests.

                                  ARTICLE VIII.

                                    MANAGERS

         Section 8.1. Selection of Managers.  Management of the Company shall be
vested in the  Managers.  Initially,  the Company  shall have five (5) Managers,
being Ken  Shifrin,  Cheryl  Williams,  and Joe Jenkins,  M.D.,  (as the initial
Manager designees of Prime), David D. Dulaney,  M.D., and Ronald W. Barnet, M.D.
(as the initial Manager  designees of LASIK).  Thereafter,  for so long as there
are five (5) Managers, (a) Prime shall be entitled to designate three (3) of the
Managers;  and (b) LASIK shall be entitled to designate the remaining two (2) of
the Managers.  Notwithstanding the foregoing,  a Member shall not be entitled to
designate any Manager unless its Membership Interest: (x) has not (other than as
allowed  under Section 2.5 of this  Agreement)  been  transferred,  repurchased,
assigned,  pledged,  hypothecated  or in any way  alienated;  and (y)  equals or
exceeds forty percent (40%) of the  aggregate  Membership  Interests;  provided,
however,  that if the immediately  preceding subsection (y) shall apply to LASIK
solely  because of an exercise by LASIK of its put rights  under  Section 9.8 of
the  Contribution  Agreement,  then LASIK  shall,  unless and until  there is an
additional decrease in it Membership Interest other than pursuant to Section 9.8
of the Contribution  Agreement, be entitled to designate only one Manager in the
manner provided above.  The Members may, by unanimous vote of all Members,  from
time to time,  change the number of  Managers  of the  Company and remove or add
Managers accordingly. A Manager shall serve as a Manager until their resignation
or removal  pursuant to Section 8.2 or 8.3 of this Article  VIII.  Managers need
not be residents of the State of Delaware or Members of the Company.

         Section 8.2. Resignations.  Each Manager shall have the right to resign
at any time upon  written  notice of such  resignation  to the  Members.  Unless
otherwise  specified in such written notice,  the resignation  shall take effect
upon the  receipt  thereof,  and  acceptance  of such  resignation  shall not be
necessary to make same effective.  The Member who designated a resigning manager
shall be entitled to designate  the  successor  thereto and all Members agree to
take such action as may be necessary to cause the election of all such successor
Managers.

         Section 8.3.  Removal of Managers.  Any Manager may be removed,  for or
without cause,  at any time, but only by the Member who designated such Manager,
upon the written notice to all Members.  The Member who designated  such removed
Manager  shall be entitled to designate  the  successor  thereto and all Members
agree to take such action as may be  necessary to cause the election of all such
successor Managers.

         Section  8.4.  General  Powers.  The  business of the Company  shall be
managed by its Managers, which may, by the vote or written consent in accordance
with this  Agreement,  exercise any and all powers of the Company and do any and
all such  lawful  acts and  things  as are not by the Act,  the  Certificate  of
Formation or this Limited Liability Company Agreement directed or required to be
exercised or done by the Members, including, but not limited to, contracting for
or incurring on behalf of the Company debts,  liabilities and other obligations,
without the consent of any other person, except as otherwise provided herein.

     Section 8.5. Place of Meetings.  The Managers of the Company may hold their
meetings,  both  regular  and  special,  either  within or without  the State of
Delaware.

         Section 8.6. Annual Meetings.  The annual meeting of the Managers shall
be held without further notice  immediately  following the annual meeting of the
Members, and at the same place, unless by unanimous consent of the Managers that
such time or place shall be changed.

     Section 8.7. Regular Meetings. Regular meetings of the Managers may be held
without  notice at such time and place as shall from time to time be  determined
by the Managers.

     Section  8.8.  Special  Meetings.  Special  meetings  of the Mangers may be
called by any Manager on seven (7) days notice to each Manager, with such notice
to be given personally, by mail or by telecopy, telegraph or mailgram.

         Section  8.9.  Quorum and Voting.  At all  meetings of the Managers the
presence of at least four (4) Managers  shall be  necessary  and  sufficient  to
constitute a quorum for the transaction of business, and the affirmative vote of
at least a majority of the  Managers  present at any meeting at which there is a
quorum shall be the act of the Managers, except as may be otherwise specifically
provided by the Act, the Contribution Agreement, the Certificate of Formation or
this Agreement. If a quorum shall not be present at any meeting of Managers, the
Managers  present there may adjourn the meeting from time to time without notice
other  than  announcement  at the  meeting,  until a quorum  shall  be  present.
Notwithstanding any voting, quorum, or other provisions of this Agreement to the
contrary,  the affirmative  vote of at least four (4) Managers shall be required
to effect any of the following actions:

               (a) any amendment, modification or waiver of any provision of the
          Company's Certificate of Formation or this Agreement;

               (b) effecting any mergers,  consolidations or combinations of the
          Company with other entities;

               (c)  dissolving,  liquidating,  or filing  bankruptcy  or seeking
          relief under any debtor relief law;

               (d) entering into a transaction  or other action with a Member or
          Manager;

                  (e) borrowing or incurring any  indebtedness,  other than open
         accounts  payable  to  unaffiliated  third  parties,  or  granting  any
         collateral  or  security  (by way of  guaranty  or  otherwise)  for any
         indebtedness or obligation,  that exceeds (in any single transaction or
         directly related series of transactions) $25,000;

                  (f) purchasing or leasing assets or property, or entering into
         any  contract  or  obligation,  which  obligates  the Company to pay in
         excess  of  $25,000  in  one  or  any   directly   related   series  of
         installments;

               (g) selling, leasing or otherwise transferring  substantially all
          of the  Company's  assets  other  than in the  ordinary  course of the
          Company's business;

                  (h)  except  as  expressly  set forth in  Section  9.12 of the
         Contribution Agreement, allocating to the Company any costs or expenses
         that are paid or  incurred by any Member or its  affiliates  (excluding
         the Company),  or paid by the Company but reimbursable by any Member or
         its affiliates (excluding the Company), in each instance;

                  (i)   issuance of any ownership interest in the Company; and

                  (j)  disposition,  sale,  assignment or other  transfer by the
         Company  of any  interest  it owns in the  Company,  except  that  such
         interest may be extinguished  without the approval  required under this
         Section.

         Section 8.10.  Committees.  The Managers  may, by resolution  passed by
eighty percent (80%) of the Managers,  designate  committees,  each committee to
consist  of two or more  Managers  (at  least  one of  which  must be a  Manager
designee of Prime and one of which must be a Manager  designee of LASIK),  which
committees  shall have such power and authority and shall perform such functions
as may be provided in such  resolution.  Such committee or committees shall have
such name or names as may be  designated  by the Managers and shall keep regular
minutes of their proceedings and report the same to the Managers when required.

         Section  8.11.  Compensation  of Managers.  The Members  shall have the
authority  to  provide,  by  unanimous  approval,  that  any  one or more of the
Managers  shall not be  compensated,  and may, by  unanimous  approval,  fix any
compensation  (which may include  expenses) they elect to pay to any one or more
of the Managers.

         Section  8.12.  Action by  Written  Consent.  Any  action  required  or
permitted  to be  taken  at any  meeting  of the  Managers  or of any  committee
designated  by the Managers may be taken  without a meeting if written  consent,
setting  forth the  action so taken,  is signed by all the  Managers  or of such
committee,  and such consent shall have the same force and effect as a unanimous
vote at a meeting.

         Section 8.13. Meetings by Conference Telephone.  Managers or members of
any committee  designated by the Managers may  participate in and hold a meeting
of the Managers or such  committee by means of  conference  telephone or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

     Section  8.14.  Liability of Managers.  No Manager of the Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment, decree, or order of the court.

         Section 8.15.  Specific Power of Managers.  The Managers shall have the
authority to enter into and execute all  documents in relation to the  formation
of the Company  including,  but not limited to,  issuance of the  Certificate of
Formation and this Limited Liability Company Agreement.

                                   ARTICLE IX.

                                     NOTICES

         Section 9.1. Form of Notice.  Whenever under the provisions of the Act,
the Certificate of Formation or this Limited  Liability Company Agreement notice
is required to be given to any Manager or Member, and no provision is made as to
how such notice shall be given,  notice shall not be construed to mean  personal
notice only, but any such notice may also be given in writing,  by mail, postage
prepaid,  addressed  to such Manager or Member at such address as appears on the
books of the Company, or by telecopy, telegraph or mailgram. Any notice required
or  permitted  to be given by mail  shall be deemed  to be given  three (3) days
after it is deposited, postage prepaid, in the United States mail as aforesaid.

         Section 9.2. Waiver. Whenever any notice is required to be given to any
Manager or Member of the Company under the provision of the Act, the Certificate
of Formation or this Limited  Liability Company  Agreement,  a waiver thereof in
writing signed by the person or persons entitled to such notice,  whether signed
before or after the time stated in such waiver,  shall be deemed  equivalent  to
the giving of such notice.

                                   ARTICLE X.

                                    OFFICERS

         Any Manager may also serve as an officer of the  Company.  The Managers
may  designate  one or more persons who are not Managers of the Company to serve
as officers and may designate the titles of all officers.  The initial  officers
of the Company shall be: Ken Shifrin,  Chairman of the Board; Joe Jenkins, M.D.,
President;  Cheryl  Williams,  Vice  President,  Secretary  and Chief  Financial
Officer;  and Mark Rosenberg,  Vice President.  Unless  otherwise  provided in a
resolution of the Members or Managers the officers of the Company shall have the
powers  designated  with  respect to such  offices  under the  Delaware  Limited
Liability Company Act, and any successor statute, as amended from time-to-time.

                                   ARTICLE XI.

                                    INDEMNITY

         Section 11.1.  Indemnification.  The Company shall indemnify any person
who was or is a party or is  threatened  to be made a party  to any  threatened,
pending or  completed  action,  suit or  proceeding,  whether  civil,  criminal,
administrative, arbitrative or investigative, any appeal in such an action, suit
or  proceeding  and any  inquiry  or  investigation  that  could lead to such an
action,  suit or proceeding  (whether or not by or in the right of the Company),
by reason of the fact that such person is or was a manager, officer, employee or
agent of the  Company or is or was  serving at the  request of the  Company as a
director,  manager, officer, partner, venturer,  proprietor,  trustee, employee,
agent or similar  functionary  of another  corporation,  employee  benefit plan,
other enterprise,  or other entity, against all judgments,  penalties (including
excise and similar taxes), fines, settlements and reasonable expenses (including
attorneys'  fees and court  costs)  actually and  reasonably  incurred by him in
connection with such action,  suit or proceeding to the fullest extent permitted
by any  applicable  law,  and such  indemnity  shall inure to the benefit of the
heirs,  executors and administrators of any such person so indemnified  pursuant
to this Article XI. The right to indemnification  under this Article XI shall be
a contract  right and shall not be deemed  exclusive of any other right to which
those seeking  indemnification may be entitled under any law, bylaw,  agreement,
vote of members or disinterested managers or otherwise, both as to action in his
official  capacity  and as to action in  another  capacity  while  holding  such
office. Any repeal or amendment of this Article XI by the Members of the Company
or by changes in  applicable  law shall,  to the extent  permitted by applicable
law, be prospective only, and shall not adversely affect the  indemnification of
any person who may be indemnified at the time of such repeal or amendment.

         Section   11.2.   Indemnification   Not   Exclusive.   The   rights  of
indemnification  and reimbursement  provided for in this Article XI shall not be
deemed  exclusive  of any  other  rights  to which  any such  Manager,  officer,
employee or agent may be  entitled  under the  Certificate  of  Formation,  this
Limited  Liability  Company  Agreement,  agreement  or vote of Members,  or as a
matter of law or otherwise.

         Section  11.3.  Other  Indemnification  Clauses.   Notwithstanding  the
foregoing,   this  Article  XI  shall  not  be  construed  to   contradict   the
indemnification   provision  of  the  Contribution  Agreement.   Notwithstanding
anything  contained  herein,  this Article XI shall be ineffectual and shall not
permit or require  indemnification for all, or any, losses, costs,  liabilities,
claims or expenses arising, directly or indirectly,  from any action or omission
permitting or requiring indemnification under the Contribution Agreement; and in
no event may any  indemnity be allowed  under this  Agreement or pursuant to any
provision   of  the  Act  for  an  amount  paid  or  payable   pursuant  to  the
indemnification provisions of the Contribution Agreement.

                                  ARTICLE XII.

                                  MISCELLANEOUS

     Section 12.1. Fiscal Year. The fiscal year of the Company shall be fixed by
resolution of the Managers.

     Section 12.2.  Records.  At the expense of the Company,  the Managers shall
maintain  records and accounts of all  operations of the Company.  At a minimum,
the Company shall keep at its principal place of business the following records:

               (a) A current list of the name and last known mailing  address of
          each Member;

               (b) A current list of each Member's Membership Interest;

                  (c) A  copy  of  the  Certificate  of  Formation  and  Limited
         Liability Company Agreement of the Company, and all amendments thereto,
         together with executed copies of any powers of attorney;

               (d) Copies of the  Federal,  state,  and local income tax returns
          and reports for the Company's six most recent tax years; and

               (e)  Correct  and  complete  books and  records of account of the
          Company.

         Section 12.3. Seal. The Company may by resolution of the Managers adopt
and have a seal, and said seal may be used by causing it or a facsimile  thereof
to be  impressed  or  affixed or in any manner  reproduced.  Any  officer of the
Company shall have authority to affix the seal to any document requiring it.

     Section 12.4. Agents.  Every Manager and Officer is an agent of the Company
for the purpose of the business. The act of a Manager or Officer,  including the
execution  in the name of the Company of any  instrument  for carrying on in the
usual way the business of the Company, binds the Company.

         Section 12.5. Checks. All checks,  drafts and orders for the payment of
money,  notes  and other  evidences  of  indebtedness  issued in the name of the
Company  shall be  signed  by such  officer,  officers,  agent or  agents of the
Company  and in such  manner  as  shall  from  time to  time  be  determined  by
resolution of the Managers. In the absence of such determination by the Mangers,
such  instruments  shall  be  signed  by  the  Treasurer  or the  Secretary  and
countersigned  by the  President  or a Vice  President  of the  Company,  if the
Company has such officers.

     Section 12.6.  Deposits.  All funds of the Company shall be deposited  from
time to time to the credit of the  Company in such  banks,  trust  companies  or
other depositories as the Managers may select.

         Section  12.7.  Annual  Statement.  The Managers  shall present at each
annual  meeting,  and,  when called for by vote of the  Members,  at any special
meeting of the Members, a full and clear statement of the business and condition
of the Company.

         Section 12.8.  Financial  Statements.  As soon as practicable after the
end of each fiscal year of the  Company,  a balance  sheet as at the end of such
fiscal year,  and a profit and loss  statement  for the period  ended,  shall be
distributed  to the  Members,  along with such tax  information  (including  all
information  returns) as may be necessary for the  preparation of each Member of
its Federal,  state and local income tax returns.  The balance  sheet and profit
and loss statement  referred to in the previous  sentence may be as shown on the
Company's federal income tax return.

         Section 12.9. Binding Arbitration.  Any controversy between the parties
regarding  this  Agreement and any claims  arising out of this  Agreement or its
breach  shall be submitted  to  arbitration  by either  party.  The  arbitration
proceedings shall be conducted by a single arbitrator pursuant to the Commercial
Arbitration Rules of the American Arbitration Association. The arbitration shall
be conducted in Dallas,  Texas and the arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

                                  ARTICLE XIII.

                                   AMENDMENTS

         Section 13.1.  Amendments.  This  Agreement may be altered,  amended or
repealed and a new limited liability  company agreement may be adopted,  only in
accordance  with the  provisions  of Section 8.9,  but  otherwise at any regular
meeting or at any special meeting called for that purpose,  or by execution of a
written consent in accordance with the provisions of Section 3.8.

         Section 13.2. When Limited  Liability  Company  Agreement Silent. It is
expressly recognized that when the Limited Liability Company Agreement is silent
or in conflict with the  requirements  of the Act as to the manner of performing
any Company function, the provisions of the Act shall control.

                            [Signature page follows]


<PAGE>





                                SIGNATURE PAGE TO

                                             LIMITED LIABILITY COMPANY AGREEMENT

         IN WITNESS WHEREOF,  the undersigned  Members hereby adopt this Limited
Liability  Company  Agreement as the Limited  Liability Company Agreement of the
Company, effective as of the 1st day of September, 1999.

                                                     LASIK Investors, L.L.C.

                                              By:
                                                 Ronald W. Barnet, M.D., manager

                                              By:
                                                 David D. Dulaney, M.D., manager

                          Prime Medical Operating, Inc.

                                                     By:

                                                     Printed Name:

                                                     Title:



<PAGE>






                                    EXHIBIT A

                               OWNERSHIP INTERESTS

Name                                                     Ownership Percentage

Prime                                                           60%

LASIK                                                           40%

<PAGE>

                                   EXHIBIT-C

                       LIMITED LIABILITY COMPANY AGREEMENT
                        OF PRIME/BDEC ACQUISITION, L.L.C.
     Organized under the Delaware Limited Liability Company Act (the "Act").

                                   ARTICLE I.
                                NAME AND LOCATION

     Section 1.1. Name. The name of this limited liability company is Prime/BDEC
Acquisition, L.L.C. (the "Company"). ----

         Section  1.2.  Members.  The  only  members  of the  Company  upon  the
execution of this Limited Liability Company Agreement (this  "Agreement")  shall
be Prime Medical Operating,  Inc, a Delaware corporation  ("Prime"),  and Barnet
Dulaney Eye Center,  P.L.L.C., an Arizona professional limited liability company
("BDEC"). For purposes of this Agreement, the "Members" shall include such named
members and any new members  admitted  pursuant to the terms of this  Agreement,
but does not  include  any person or entity who has ceased to be a member in the
Company.

     Section 1.3. Principal Office. The principal office of the Company shall be
located in 1301 Capital of Texas Hwy., Suite C-300, Austin, Texas 78746-6550, or
such other location as may be selected by the Members. ----------------

     Section 1.4. Registered Agent and Address. The name of the registered agent
and the  address  of the  registered  office of the  Company as set forth in the
Certificate of Formation of the Company are: -----------------------------
                                            The Corporation Trust Company
                                            1209 Orange Street
                                            Wilmington, Delaware 19801

     Section 1.5.  Other  Offices.  Other offices and other  facilities  for the
transaction of business shall be located at such places as the Managers may from
time to time determine. -------------

         Section 1.6  Contribution  Agreement.  The Company was initially formed
with a single member,  BDEC, for the purpose of  consummating  the  transactions
contemplated by that certain Contribution Agreement dated effective September 1,
1999, by and among Prime, Prime Medical Services,  Inc., a Delaware  corporation
("PMSI"), BDEC, the Company,  Prime/BDR Acquisition,  L.L.C., a Delaware limited
liability  company,  LASIK  Investors,  L.L.C.,  a  Delaware  limited  liability
company, David D. Dulaney, M.D., Ronald W. Barnet, M.D., and Mark Rosenberg (the
"Contribution  Agreement").  The  parties  have  executed  this  Agreement  upon
consummation of the  transactions  contemplated by the  Contribution  Agreement.
This agreement  supercedes and replaces any prior membership  agreement or other
governing or organizational document of the Company.

                                                    ARTICLE II.
                                                    MEMBERSHIP

     Section 2.1. Members' Interests.  The "Membership  Interest" of each Member
is set forth on Exhibit A. ------------------ ---------

     Section 2.2. Admission to Membership. The admission of new Members shall be
only by the vote of the Managers  pursuant to Section 8.9 hereof. If new Members
are admitted,  this Agreement shall be amended to reflect each Member's  revised
Membership Interest. -----------------------

     Section 2.3.  Property  Rights.  No Member shall have any right,  title, or
interest in any of the property or assets of the Company. ---------------

     Section  2.4.  Liability  of  Members.  No Member of the  Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment decree, or order of court. --------------------

         Section 2.5.  Transferability of Membership.  Except as provided below,
Membership  Interests in the Company are  transferable  only with the  unanimous
written  consent  of all  Members.  If such  unanimous  written  consent  is not
obtained when  required,  the  transferee  shall be entitled to receive only the
share of  profits  or other  compensation  by way of  income  and the  return of
contributions  to which  the  transferor  Member  otherwise  would be  entitled.
Notwithstanding  the  foregoing,  (i) the  Membership  Interests of Prime may be
freely  transferred,  without  consent,  to any  entity  that is then  owned  or
controlled,  directly or indirectly, by Prime Medical Services, Inc., a Delaware
corporation (or its successor in interest), (ii) the Membership Interests of any
Member  may be  freely  assigned,  pledged  or  otherwise  transferred,  without
consent,  to  secure  any debt,  liability  or  obligation  owed to Prime by the
Company,  any  Member  or any  entity  affiliated  with the  Company,  (iii) the
Membership Interests of any Member may be freely assigned,  pledged or otherwise
transferred,  without  consent,  in  favor  of the  Lender(s)  under,  or by the
Lender(s)  as a result  of the  enforcement  of any  security  interest  arising
pursuant to, that certain  Senior  Credit  Facility  (the "Credit  Facility") of
PMSI, and (iv) the pledge by BDEC  (pursuant to Section 6.3 of the  Contribution
Agreement) of its right to receive  distributions from the Company in respect of
its  Membership  Interest  shall not be deemed to violate any  provision of this
Agreement.

     Section 2.6.  Resignation  of Members.  A Member may not withdraw  from the
Company except on the unanimous consent of the remaining  Members.  The terms of
the Members  withdrawal  shall be determined by agreement  between the remaining
Members and the withdrawing Member. ----------------------

                                                   ARTICLE III.
                                                 MEMBERS' MEETINGS

     Section 3.1.  Time and Place of Meeting.  All meetings of the Members shall
be held at such time and at such place  within or without  the State of Delaware
as shall be determined by the Managers. -------------------------

     Section 3.2. Annual Meetings.  In the absence of an earlier meeting at such
time and place as the Managers  shall  specify,  annual  meetings of the Members
shall be held at the principal office of the Company on the date which is thirty
(30) days after the end of the Company's fiscal year if not a legal holiday, and
if a legal holiday, then on the next full business day following, at 10:00 a.m.,
at which  meeting the  Members may  transact  such  business as may  properly be
brought before --------------- the meeting.

     Section  3.3.  Special  Meetings.  Special  meetings  of the Members may be
called at any time by any Member.  Business transacted at special meetings shall
be   confined   to  the   purposes   stated  in  the  notice  of  the   meeting.
- ----------------

         Section 3.4.  Notice.  Written or printed notice stating the place, day
and hour of any Members'  meeting,  and, in the case of a special  meeting,  the
purpose or purposes for which the meeting is called, shall be delivered not less
than ten (10) days nor more than thirty (30) days before the date of the special
meeting,  either  personally  or by mail,  by or at the  direction of the person
calling the meeting, to each Member entitled to vote at such meeting. If mailed,
such notice shall be deemed to be delivered three (3) days after it is deposited
in the United States mail,  postage prepaid,  to the Member at his address as it
appears on the records of the Company at the time of mailing.

         Section 3.5. Quorum. Members present in person or represented by proxy,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any meeting  shall  constitute  a quorum at all  meetings of the Members for the
transaction  of  business.  If,  however,  such  quorum  shall not be present or
represented at any meeting of the Members, the Members entitled to vote, present
in person or represented by proxy,  shall have power to adjourn the meeting from
time to time,  without notice other than  announcement  at the meeting,  until a
quorum shall be present or represented. When any adjourned meeting is reconvened
and a quorum shall be present or  represented,  any  business may be  transacted
which might have been  transacted at the meeting as originally  noticed.  Once a
quorum is constituted,  the Members present or represented by proxy at a meeting
may  continue  to  transact  business  until  adjournment,  notwithstanding  the
subsequent  withdrawal therefrom of such number of Members as to leave less than
a quorum.

         Section  3.6.  Voting.  Members  shall  only  be  required  to  vote in
instances  or with  respect  to  matters  where  member  voting is  required  by
applicable  law or to the extent  expressly  contemplated  in Section 8.1.  With
respect to any act or  transaction  that  requires a vote by the  Members  under
applicable law, the affirmative  vote of not less than three (3) of the Managers
shall also be  required  in order to  approve  the act or  transaction,  in each
instance. Subject to the foregoing, when a quorum is present at any meeting, the
vote of the Members,  whether  present or  represented by proxy at such meeting,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any  meeting  shall be the act of the  Members,  unless the vote of a  different
number is required by the Act,  the  Certificate  of  Formation  or this Limited
Liability Company Agreement.  Each Member shall be entitled to one vote for each
percentage point represented by their Membership Interest. Fractional percentage
point  interests  shall be  entitled to a  corresponding  fractional  vote.  The
provisions of this Section shall not  interfere  with the  provisions of Section
8.9 relating to acts or transactions requiring the written approval of three (3)
or more Managers.  Each Member acknowledges and agrees that, in the event of any
exercise of the Repurchase  Option,  as defined in the  Contribution  Agreement,
each Member will vote its entire  Membership  Interest in favor of  transferring
the Company's assets pursuant to the Repurchase Option.

     Section 3.7.  Proxy.  Every proxy must be executed in writing by the Member
or by his  duly  authorized  attorney-in-fact,  and  shall  be  filed  with  the
Secretary of the Company prior to or at the time of the meeting.  No proxy shall
be  valid  after  eleven  (11)  months  from the  date of its  execution  unless
otherwise  provided  therein.  Each proxy shall be  revocable  unless  expressly
provided therein to be irrevocable and unless otherwise made irrevocable by law.
- -----

     Section 3.8. Action by Written Consent. Any action required or permitted to
be taken at any  meeting  of the  Members  may be taken  without a meeting  if a
consent in writing, setting forth the action so taken, shall be signed by all of
the Members  entitled to vote with respect to the subject  matter  thereof,  and
such  consent  shall  have the same  force  and  effect as a  unanimous  vote of
Members. -------------------------

     Section 3.9. Meetings by Conference  Telephone.  Members may participate in
and hold  meetings  of  Members  by means of  conference  telephone  or  similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction     of    any     business     on    the     ground     that     the
- -------------------------------- meeting is not lawfully called or convened.

                                   ARTICLE IV.
                        MEMBERSHIP CAPITAL CONTRIBUTIONS

         Except  for  each  Member's  initial  capital   contribution   made  in
connection with the formation of the Company, no capital  contributions shall be
required  of any  Member  without  the  approval  of all the  Members  to  raise
additional capital, and only then proportionately as to each Member.

                                                    ARTICLE V.
                                              DISTRIBUTION TO MEMBERS

         At the end of each calendar quarter, subject only to the qualifications
and  limitations  set forth below,  the Company shall  distribute  its available
excess  earnings to its members,  to be divided  among them in  accordance  with
their Membership Interests.  Distributions in kind shall be made on the basis of
agreed value as determined by the Members.  Notwithstanding  the foregoing,  the
Company  may  not  make a  distribution  to its  Members  to  the  extent  that,
immediately  after giving effect to the  distribution,  all  liabilities  of the
Company,  other than  liabilities to the Members with respect to their interests
and  liabilities  for which the  recourse of  creditors  is limited to specified
property of the  Company,  exceed the fair value of the Company  assets;  except
that the fair value of property that is subject to liability for which  recourse
of  creditors  is limited,  shall be included in the Company  assets only to the
extent that the fair value of the property exceeds that liability.

                                   ARTICLE VI.
              ALLOCATION OF NET PROFITS AND LOSSES FOR TAX PURPOSES

         For  accounting  and income tax  purposes,  all items of income,  gain,
loss,  deduction,  and  credit of the  Company  for any  taxable  year  shall be
allocated  among the  Members in  accordance  with their  respective  Membership
Interests,  except as may be otherwise  required by the Internal Revenue Code of
1986, as amended.

                                  ARTICLE VII.
                           DISSOLUTION AND WINDING UP

     Section 7.1.  Dissolution.  Notwithstanding  any  provision of the Act, the
Company  shall be  dissolved  only  upon the  first of the  following  to occur:
- -----------

          (a) Forty  (40)  years  from the date of  filing  the  Certificate  of
     Formation of the Company;

          (b) Written consent of all the then current Members to dissolution;

          (c) The bankruptcy of a Member, unless there is at least one remaining
     Member and such Member or, if more than one remaining Member, all remaining
     Members  agree to  continue  the  Company and its  business.  Section  7.2.
     Winding Up. Unless the Company is continued  pursuant to Section  7.1(c) of
     this Article VII., in the event of dissolution of the Company, the Managers
     (excluding  any  Manager(s)  holding  office  pursuant to  designation by a
     Member  subject to  bankruptcy  proceedings)  shall  wind up the  Company's
     affairs  as  soon  as  reasonably  practicable.  On the  winding  up of the
     Company,  the Managers shall pay and/or  transfer the assets of the Company
     in the following order: ----------

          (a) In discharging  liabilities (including loans from Members) and the
     expenses of concluding the Company's affairs; and

                  (b) The balance,  if any, shall be divided between the Members
in accordance with the Members' Membership Interests.

                                  ARTICLE VIII.
                                    MANAGERS

         Section 8.1. Selection of Managers.  Management of the Company shall be
vested in the  Managers.  Initially,  the Company  shall have four (4) Managers,
being Ken  Shifrin,  Joe Jenkins,  M.D.,  (as the initial  Manager  designees of
Prime),  David D.  Dulaney,  M.D.  and Ronald W. Barnet,  M.D.,  (as the initial
Manager  designees  of  BDEC).  Thereafter,  for so long as  there  are four (4)
Managers,  (a) Prime shall be entitled to designate two (2) of the Managers; and
(b) BDEC shall be entitled to designate  the  remaining two (2) of the Managers.
Notwithstanding  the foregoing,  a Member shall not be entitled to designate any
Manager unless its Membership Interest: (x) has not (other than as allowed under
Section 2.5 of this Agreement) been transferred, repurchased, assigned, pledged,
hypothecated  or in any way  alienated;  and (y) equals or exceeds forty percent
(40%) of the aggregate Membership Interests.  The Members may, by unanimous vote
of all Members,  from time to time, change the number of Managers of the Company
and remove or add Managers accordingly. A Manager shall serve as a Manager until
their  resignation  or removal  pursuant to Section  8.2 or 8.3 of this  Article
VIII.  Managers need not be residents of the State of Delaware or Members of the
Company.

          Section 8.2. Resignations. Each Manager shall have the right to resign
     at any time upon written notice of such resignation to the Members.  Unless
     otherwise  specified in such written  notice,  the  resignation  shall take
     effect upon the receipt thereof,  and acceptance of such resignation  shall
     not be  necessary  to make same  effective.  The  Member who  designated  a
     resigning  manager shall be entitled to designate the successor thereto and
     all Members agree to take such action as may be  ------------  necessary to
     cause the election of all such successor Managers.

          Section 8.3. Removal of Managers.  Any Manager may be removed,  for or
     without  cause,  at any time,  but only by the Member who  designated  such
     Manager,  upon the written notice to all Members. The Member who designated
     such removed  Manager shall be entitled to designate the successor  thereto
     and all Members  agree to take such action as may be necessary to cause the
     election of all such successor Managers. -------------------

         Section  8.4.  General  Powers.  The  business of the Company  shall be
managed by its Managers, which may, by the vote or written consent in accordance
with this  Agreement,  exercise any and all powers of the Company and do any and
all such  lawful  acts and  things  as are not by the Act,  the  Certificate  of
Formation or this Limited Liability Company Agreement directed or required to be
exercised or done by the Members, including, but not limited to, contracting for
or incurring on behalf of the Company debts,  liabilities and other obligations,
without the consent of any other person, except as otherwise provided herein.

          Section 8.5.  Place of Meetings.  The Managers of the Company may hold
     their  meetings,  both  regular and special,  either  within or without the
     State of Delaware. -----------------

          Section 8.6. Annual Meetings. The annual meeting of the Managers shall
     be held without further notice immediately  following the annual meeting of
     the  Members,  and at the same place,  unless by  unanimous  consent of the
     Managers that such time or place shall be changed. ---------------

          Section 8.7. Regular Meetings. Regular meetings of the Managers may be
     held  without  notice at such time and place as shall  from time to time be
     determined by the Managers. ----------------

          Section 8.8. Special Meetings.  Special meetings of the Mangers may be
     called by any Manager on seven (7) days notice to each  Manager,  with such
     notice  to be  given  personally,  by mail  or by  telecopy,  telegraph  or
     mailgram. ----------------

         Section  8.9.  Quorum and Voting.  At all  meetings of the Managers the
presence of at least three (3) Managers  shall be necessary  and  sufficient  to
constitute a quorum for the transaction of business, and the affirmative vote of
at least a majority of the  Managers  present at any meeting at which there is a
quorum shall be the act of the Managers, except as may be otherwise specifically
provided by the Act, the Contribution Agreement, the Certificate of Formation or
this Agreement. If a quorum shall not be present at any meeting of Managers, the
Managers  present there may adjourn the meeting from time to time without notice
other  than  announcement  at the  meeting,  until a quorum  shall  be  present.
Notwithstanding  any  other  Member  or  Manager  voting  or  quorum  provisions
contained  in  this  Agreement,  the  following  acts  or  transactions  by,  or
involving,  the Company shall  require the prior  written  approval of three (3)
Managers  (unless and to the extent a particular act or transaction is expressly
required of the Company pursuant to the terms and provisions of the Contribution
Agreement or any Transaction Document):

          (a) Any  amendment to the Company's  Certificate  of Formation or this
     Agreement.

          (b)  Mergers,  consolidations  or  combinations  of the  Company  with
     another limited liability company or other entity.

                  (c)  Purchase by the Company of any  interest in the  Company,
irrespective of the source of such interest.

          (d) Disposition,  sale, assignment or other transfer by the Company of
     any  interest  it owns in the  Company,  except that such  interest  may be
     extinguished without the approval required under this Article.

                  (e)      Issuance of any interest in the Company to any party.

                  (f) Dissolving,  liquidating,  or filing bankruptcy or seeking
relief under any debtor relief law.

                  (g)  Election  or removal of  officers,  and  establishing  or
changing the compensation for Managers, officers or other employees.

          (h) Not making any cash distributions to its Members that are required
     by this Agreement to be made, or making any distributions to its Members of
     cash or property that are prohibited under this Agreement.

          (i) Sale, lease or other transfer of all or  substantially  all of the
     Company's  assets,  or any assets other than in the ordinary  course of the
     Company's business.

                  (j)  Initiating  or  settling  any  litigation  or  regulatory
proceeding, or confessing any judgment.

                  (k) Hiring or  changing  the  Company's  accountants  or legal
counsel.

                  (l) Opening or closing bank or other depository accounts,  and
establishing or changing the signature  withdrawal authority with respect to any
such accounts.

          (m) Borrowing or incurring any indebtedness,  other than open accounts
     payable to  unaffiliated  third  parties,  or granting  any  collateral  or
     security  (by  way of  guaranty  or  otherwise)  for  any  indebtedness  or
     obligation.

                  (n)  Engaging in any act or  transaction  not in the  ordinary
course of the Company's business.

          (o)  Purchasing  or leasing  assets or property,  or entering into any
     contract or  obligation,  which  obligates  the Company to pay in excess of
     $10,000 in the aggregate in one or any series of installments.

          (p) Doing any  business  other than the  conduct of the  Business  (as
     defined in the Contribution Agreement) or causing a change in the nature of
     the business or the legal name of the Company.

                  (q)  Entering  into a  transaction  or other  action  with any
Manager, officer or Member.

          (r) Waiving, refusing to enforce, amending, restating,  superseding or
     modifying  any of the  provisions  of  this  Agreement  or any  Transaction
     Document, including, without limitation, the Collocation Agreement.

          (s) Taking any other  action  which,  by the terms of this  Agreement,
     requires  the  approval  or consent of not less than  seventy-five  percent
     (75%) of the Members.

          (t) Except as  expressly  set forth in the  Collocation  Agreement  or
     Section 9.12 of the Contribution  Agreement,  allocating to the Company any
     costs or expenses that are paid or incurred by any Member or its affiliates
     (excluding  the Company),  or paid by the Company but  reimbursable  by any
     Member or its affiliates (excluding the Company), in each instance.

          (u) With respect to the business and  operations of Newco II conducted
     or to be conducted  at or near the  location of 4800 N. 22nd St.,  Phoenix,
     Arizona,  waiving,   amending,   supplementing  or  modifying  any  of  the
     professional  fees,  facility fees or fee  allocations  by Newco II, to the
     extent such amounts or allocations were utilized in preparing the pro forma
     financial statements of Newco II attached to the Collocation Agreement.

          (v) With respect to the business and  operations of Newco II conducted
     or to be  conducted  at any  other  future  office  or  business  locations
     (including  without  limitation,  the office  located at 555 E. River Road,
     Tucson,  Arizona),  adopting any  professional  fees,  facility fees or fee
     allocations.

         Any of the  above  stated  actions  taken by the  Company  without  the
necessary manager approval is void ab initio.

         Section 8.10.  Committees.  The Managers  may, by resolution  passed by
eighty percent (80%) of the Managers,  designate  committees,  each committee to
consist  of two or more  Managers  (at  least  one of  which  must be a  Manager
designee of Prime and one of which must be a Manager  designee  of BDEC),  which
committees  shall have such power and authority and shall perform such functions
as may be provided in such  resolution.  Such committee or committees shall have
such name or names as may be  designated  by the Managers and shall keep regular
minutes of their proceedings and report the same to the Managers when required.

          Section  8.11.  Compensation  of Managers.  The Members,  by unanimous
     approval,  shall have the  authority to provide that any one or more of the
     Managers shall not be compensated,  and may, by unanimous approval, fix any
     compensation  (which may include  expenses) they elect to pay to any one or
     more of the Managers. ------------------------

          Section  8.12.  Action by  Written  Consent.  Any action  required  or
     permitted  to be taken at any meeting of the  Managers or of any  committee
     designated  by the  Managers  may be taken  without  a meeting  if  written
     consent,  setting forth the action so taken,  is signed by all the Managers
     or of such committee, and such consent shall have the same force and effect
     as a unanimous vote at a meeting. -------------------------

         Section 8.13. Meetings by Conference Telephone.  Managers or members of
any committee  designated by the Managers may  participate in and hold a meeting
of the Managers or such  committee by means of  conference  telephone or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

          Section 8.14.  Liability of Managers.  No Manager of the Company shall
     be personally  liable for any debts,  liabilities,  or  obligations  of the
     Company,  including  under a  judgment,  decree,  or  order  of the  court.
     ---------------------

          Section 8.15. Specific Power of Managers.  The Managers shall have the
     authority  to enter into and  execute  all  documents  in  relation  to the
     formation  of the Company  including,  but not limited to,  issuance of the
     Certificate  of Formation  and this Limited  Liability  Company  Agreement.
     --------------------------

                                                    ARTICLE IX.
                                                      NOTICES

         Section 9.1. Form of Notice.  Whenever under the provisions of the Act,
the Certificate of Formation or this Limited  Liability Company Agreement notice
is required to be given to any Manager or Member, and no provision is made as to
how such notice shall be given,  notice shall not be construed to mean  personal
notice only, but any such notice may also be given in writing,  by mail, postage
prepaid,  addressed  to such Manager or Member at such address as appears on the
books of the Company, or by telecopy, telegraph or mailgram. Any notice required
or  permitted  to be given by mail  shall be deemed  to be given  three (3) days
after it is deposited, postage prepaid, in the United States mail as aforesaid.

          Section  9.2.  Waiver.  Whenever any notice is required to be given to
     any Manager or Member of the Company  under the  provision  of the Act, the
     Certificate of Formation or this Limited  Liability  Company  Agreement,  a
     waiver thereof in writing signed by the person or persons  entitled to such
     notice,  whether  signed  before or after the time  stated in such  waiver,
     shall be deemed equivalent to the giving of such notice. ------

                                                    ARTICLE X.
                                                     OFFICERS


         Any Manager may also serve as an officer of the  Company.  The Managers
may  designate  one or more persons who are not Managers of the Company to serve
as officers and may designate the titles of all officers.  The initial  officers
of the Company shall be: Ken Shifrin,  Chairman of the Board; Joe Jenkins, M.D.,
President;  Cheryl  Williams,  Vice  President,  Secretary  and Chief  Financial
Officer;  and Mark Rosenberg,  Vice President.  Unless  otherwise  provided in a
resolution of the Members or Managers the officers of the Company shall have the
powers  designated  with  respect to such  offices  under the  Delaware  Limited
Liability Company Act, and any successor statute, as amended from time-to-time.

                                                    ARTICLE XI.
                                                     INDEMNITY

         Section 11.1.  Indemnification.  The Company shall indemnify any person
who was or is a party or is  threatened  to be made a party  to any  threatened,
pending or  completed  action,  suit or  proceeding,  whether  civil,  criminal,
administrative, arbitrative or investigative, any appeal in such an action, suit
or  proceeding  and any  inquiry  or  investigation  that  could lead to such an
action,  suit or proceeding  (whether or not by or in the right of the Company),
by reason of the fact that such person is or was a manager, officer, employee or
agent of the  Company or is or was  serving at the  request of the  Company as a
director,  manager, officer, partner, venturer,  proprietor,  trustee, employee,
agent or similar  functionary  of another  corporation,  employee  benefit plan,
other enterprise,  or other entity, against all judgments,  penalties (including
excise and similar taxes), fines, settlements and reasonable expenses (including
attorneys'  fees and court  costs)  actually and  reasonably  incurred by him in
connection with such action,  suit or proceeding to the fullest extent permitted
by any  applicable  law,  and such  indemnity  shall inure to the benefit of the
heirs,  executors and administrators of any such person so indemnified  pursuant
to this Article XI. The right to indemnification  under this Article XI shall be
a contract  right and shall not be deemed  exclusive of any other right to which
those seeking  indemnification may be entitled under any law, bylaw,  agreement,
vote of members or disinterested managers or otherwise, both as to action in his
official  capacity  and as to action in  another  capacity  while  holding  such
office.  Any repeal or amendment of this Article XI by the Managers (pursuant to
Section  8.9  hereof)  or by  changes in  applicable  law  shall,  to the extent
permitted by applicable law, be prospective only, and shall not adversely affect
the  indemnification  of any person who may be  indemnified  at the time of such
repeal or amendment.

          Section   11.2.   Indemnification   Not   Exclusive.   The  rights  of
     indemnification and reimbursement provided for in this Article XI shall not
     be deemed exclusive of any other rights to which any such Manager, officer,
     employee or agent may be entitled under the Certificate of Formation,  this
     Limited Liability Company Agreement,  agreement or vote of Members, or as a
     matter of law or otherwise. -----------------------------

         Section  11.3.  Other  Indemnification  Clauses.   Notwithstanding  the
foregoing,   this  Article  XI  shall  not  be  construed  to   contradict   the
indemnification   provision  of  the  Contribution  Agreement.   Notwithstanding
anything  contained  herein,  this Article XI shall be ineffectual and shall not
permit or require  indemnification for all, or any, losses, costs,  liabilities,
claims or expenses arising, directly or indirectly,  from any action or omission
permitting or requiring indemnification under the Contribution Agreement; and in
no event may any  indemnity be allowed  under this  Agreement or pursuant to any
provision   of  the  Act  for  an  amount  paid  or  payable   pursuant  to  the
indemnification provisions of the Contribution Agreement.

                                                   ARTICLE XII.
                                                   MISCELLANEOUS

          Section  12.1.  Fiscal Year.  The fiscal year of the Company  shall be
     fixed by resolution of the Managers. -----------

          Section  12.2.  Records.  At the expense of the Company,  the Managers
     shall maintain records and accounts of all operations of the Company.  At a
     minimum,  the Company  shall keep at its  principal  place of business  the
     following records: -------

          (a) A current list of the name and last known mailing  address of each
     Member;
                  (b)      A current list of each Member's Membership Interest;

          (c) A copy of the  Certificate  of  Formation  and  Limited  Liability
     Company Agreement of the Company, and all amendments thereto, together with
     executed copies of any powers of attorney;

                  (d) Copies of the Federal, state, and local income tax returns
and reports for the Company's six most recent tax years; and

                  (e) Correct and  complete  books and records of account of the
Company.

          Section  12.3.  Seal.  The Company may by  resolution  of the Managers
     adopt  and  have a seal,  and  said  seal  may be used by  causing  it or a
     facsimile  thereof to be impressed or affixed or in any manner  reproduced.
     Any officer of the Company  shall have  authority  to affix the seal to any
     document requiring it. ----

          Section  12.4.  Agents.  Every  Manager and Officer is an agent of the
     Company for the purpose of the  business.  The act of a Manager or Officer,
     including  the execution in the name of the Company of any  instrument  for
     carrying  on in the  usual  way the  business  of the  Company,  binds  the
     Company. ------

         Section 12.5. Checks. All checks,  drafts and orders for the payment of
money,  notes  and other  evidences  of  indebtedness  issued in the name of the
Company  shall be  signed  by such  officer,  officers,  agent or  agents of the
Company  and in such  manner  as  shall  from  time to  time  be  determined  by
resolution of the Managers. In the absence of such determination by the Mangers,
such  instruments  shall  be  signed  by  the  Treasurer  or the  Secretary  and
countersigned  by the  President  or a Vice  President  of the  Company,  if the
Company has such officers.

          Section  12.6.  Deposits.  All funds of the Company shall be deposited
     from  time  to time to the  credit  of the  Company  in such  banks,  trust
     companies or other depositories as the Managers may select. --------

          Section 12.7.  Annual  Statement.  The Managers  shall present at each
     annual meeting a full and clear  statement of the business and condition of
     the Company. ----------------

         Section 12.8.  Financial  Statements.  As soon as practicable after the
end of each fiscal year of the  Company,  a balance  sheet as at the end of such
fiscal year,  and a profit and loss  statement  for the period  ended,  shall be
distributed  to the  Members,  along with such tax  information  (including  all
information  returns) as may be necessary for the  preparation of each Member of
its Federal,  state and local income tax returns.  The balance  sheet and profit
and loss statement  referred to in the previous  sentence may be as shown on the
Company's federal income tax return.

          Section 12.9. Binding Arbitration. Any controversy between the parties
     regarding  this  Agreement and any claims  arising out of this Agreement or
     its  breach  shall  be  submitted  to  arbitration  by  either  party.  The
     arbitration  proceedings shall be conducted by a single arbitrator pursuant
     to  the   Commercial   Arbitration   Rules  of  the  American   Arbitration
     Association.  The arbitration  shall be conducted in Dallas,  Texas and the
     arbitrator   shall   have   the   right  to  award   actual   damages   and
     -------------------  attorney fees and costs,  but shall not have the right
     to award punitive, exemplary or consequential damages against either party.

                                  ARTICLE XIII.
                                   AMENDMENTS

          Section 13.1.  Amendments.  This Agreement may be altered,  amended or
     repealed and a new limited liability company agreement may be adopted, only
     in  accordance  with the  provisions  of Section 8.9, but  otherwise at any
     regular  meeting or at any special  meeting called for that purpose,  or by
     execution of a written consent in accordance with the provisions of Section
     3.8. ----------

          Section 13.2. When Limited  Liability  Company Agreement Silent. It is
     expressly  recognized that when the Limited  Liability Company Agreement is
     silent or in conflict with the  requirements of the Act as to the manner of
     performing any Company  function,  the provisions of the Act shall control.
     -----------------------------------------------

                                             [Signature page follows]




<PAGE>





043838.0000  AUSTIN 133169 v8                       S-1


                                                 SIGNATURE PAGE TO
                                        LIMITED LIABILITY COMPANY AGREEMENT

         IN WITNESS WHEREOF,  the undersigned  Members hereby adopt this Limited
Liability  Company  Agreement as the Limited  Liability Company Agreement of the
Company, effective as of the 1st day of September, 1999.


                                          Barnet Dulaney Eye Center, P.L.L.C.


                                             By:
                                                 Ronald W. Barnet, M.D., manager

                                             By:
                                                 David D. Dulaney, M.D., manager




                                          Prime Medical Operating, Inc.

                                            By:
                                            Printed Name:
                                            Title:



<PAGE>


A-

043838.0000  AUSTIN 133169 v8


                                                     EXHIBIT A
                                                OWNERSHIP INTERESTS

Name                                                      Ownership Percentage

Prime                                                              60%

BDEC                                                               40%






<PAGE>


                                   EXHIBIT-D

                                             ASSIGNMENT AND ASSUMPTION
                                                     AGREEMENT


         For and in consideration of the sum of Ten Dollars ($10) and other good
and  valuable  consideration,  the  receipt and  sufficiency  of which is hereby
acknowledged,  and pursuant to and in accordance with that certain  Contribution
Agreement,  dated September 1, 1999,  between and among Prime Medical  Services,
Inc.,  a  Delaware  corporation,  Prime  Medical  Operating,  Inc.,  a  Delaware
corporation  ("Prime"),   Barnet  Dulaney  Eye  Center,   P.L.L.C.,  an  Arizona
professional  limited  liability company  ("BDEC"),  LASIK Investors,  L.L.C., a
Delaware limited liability company,  Prime/BDEC Acquisition,  L.L.C., a Delaware
limited  liability  company  ("Newco  II"),  Prime/BDR  Acquisition,  L.L.C.,  a
Delaware limited liability  company,  Ronald W. Barnet,  M.D., David D. Dulaney,
M.D. and Mark Rosenberg (the "Contribution Agreement"), each of Prime, BDEC, and
each of their  constituent  owners,  hereby assigns,  transfers and sets over to
Newco II, its  successors  and assigns,  as of the Effective Time (as defined in
the Contribution Agreement), with such representations, warranties and covenants
as are  expressly  set forth in the  Contribution  Agreement,  all of its right,
title and  interest  in and to the  Assets and the  Business  (as such terms are
defined in the Contribution Agreement).

     Newco II hereby  assumes,  as of the  Effective  Time,  only those lease or
contract obligations of BDEC arising under lease agreements assigned to Newco II
pursuant to the foregoing  paragraph,  and only those  liabilities set forth, by
item and amount, on Schedule 1.4 of the Contribution Agreement.  With respect to
any lease or contract  obligations assumed by Newco II pursuant to the foregoing
sentence,  Newco II only assumes  obligations  thereunder which accrue after the
Effective  Time,  and  has no  responsibility  whatsoever  for any  breaches  or
defaults  which occurred prior to the later of the Effective Time or the Closing
Date (as defined in the  Contribution  Agreement),  or for obligations  accruing
prior to the Effective Time.

         BDEC acknowledges and agrees that, except as expressly set forth in the
immediately preceding paragraph, Newco II does not assume any debts, liabilities
or  obligations  of any kind  whatsoever,  whether  known or unknown,  absolute,
contingent or otherwise (including, but not limited to, federal, state and local
taxes, any sales taxes, use taxes and property taxes, any taxes arising from the
transactions  contemplated by the  Contribution  Agreement,  and any liabilities
arising  from  any  litigation  or  civil,  criminal  or  regulatory  proceeding
involving  or related to BDEC or its  business),  and any and all of such debts,
liabilities and obligations shall remain the sole responsibility of BDEC.

                                             [Signature page follows]



<PAGE>


                                                 SIGNATURE PAGE TO
                                        ASSIGNMENT AND ASSUMPTION AGREEMENT

         IN WITNESS WHEREOF,  the parties hereto have caused this Assignment and
Assumption  Agreement to be executed by their duly  authorized  representatives,
effective for all purposes the 1st day of September, 1999.


PRIME:                             PRIME MEDICAL OPERATING, INC.

                                   By:

                                   Printed Name:

                                   Title:





BDEC:                              BARNET DULANEY EYE CENTER, P.L.L.C.


                                   By:  ________________________________
                                           Ronald W. Barnet, M.D., manager


                                   By:  ________________________________
                                           David D. Dulaney, M.D., manager





NEWCO II:                          PRIME/BDEC ACQUISITION, L.L.C.

                                   By:

                                   Printed Name:

                                   Title:




<PAGE>
                                   EXHIBIT-G1
                                                  LOAN AGREEMENT

         This Loan Agreement  (this  "Agreement") is entered into as of the ____
day of September, 1999, by and between Prime Medical Operating, Inc., a Delaware
corporation,  and Prime/BDR  Acquisition,  L.L.C., a Delaware limited  liability
company.

                                                   Definitions:

EFFECTIVE DATE:                 September ___, 1999

     BORROWER:  Prime/BDR  Acquisition,  L.L.C.,  a Delaware  limited  liability
          company
     BORROWER'S  ADDRESS:  1301 Capital of Texas Highway,  Suite C-300,  Austin,
Texas 78746
     LENDER: Prime Medical Operating, Inc., a Delaware corporation
     LENDER'S ADDRESS: 1301 Capital of Texas Highway, Suite C-300, Austin, Texas
78746
NOTES:

     Working  Capital  Note:  Promissory  Note (Line of  Credit) in the  maximum
principal  amount of $200,000 (the "Working Capital Maximum  Principal  Amount")
dated  September  ___, 1999,  executed by Borrower,  and payable to the order of
Lender as provided therein (the "Working Capital Note").
     Development  Facility  Notes:  Promissory  Notes in the  aggregate  maximum
original principal amount not to exceed  $40,000,000 (the "Development  Facility
Maximum  Principal  Amount"),  executed by Borrower  and payable to the order of
Lender as provided therein (the "Development Facility Notes"). Collectively, the
Working Capital Notes and the Development  Facility Notes are referred to herein
as the "Notes."
     SECURITY AGREEMENTS: All documents,  agreements and instruments hereinafter
or herewith  executed by Borrower,  LASIK Investors,  L.L.C., a Delaware limited
liability  company ("LASIK") or any Target Center securing this Agreement or the
obligations under any of the Notes.
          LOAN  DOCUMENTS:   This  Agreement,  the  Working  Capital  Note,  the
     Development  Facility  Notes,  the  Security  Agreements,   and  all  other
     documents,   agreements,   and  instruments  now  or  hereafter   existing,
     evidencing,  securing,  or  otherwise  relating to this  Agreement  and any
     transactions  contemplated by this Agreement, as any of the foregoing items
     may be modified or supplemented from time to time.
INDEBTEDNESS:  All present and future indebtedness,  obligations and liabilities
of Borrower to Lender,  all present  and future  indebtedness,  obligations  and
liabilities  of any Target Center to Lender,  and all renewals,  extensions  and
modifications  of either of the foregoing,  arising  pursuant to any of the Loan
Documents  and all  interest  accruing  thereon,  and  all  other  fees,  costs,
expenses, charges and attorneys' fees payable, and covenants performable,  under
any of the Loan Documents (including without limitation this Agreement).

          DEFINED  TERMS:  Terms not  otherwise  defined  herein  shall have the
     meaning  provided in that certain  Contribution  Agreement  dated effective
     September 1, 1999, by and among Barnet Dulaney Eye Center,  P.L.L.C., David
     D. Dulaney,  M.D.,  Ronald W. Barnet,  M.D., Mark Rosenberg,  Prime Medical
     Services, Inc., Lender, Borrower, LASIK and Prime/BDEC Acquisition,  L.L.C.
     (the "Contribution  Agreement").  For the purposes hereof the terms "Target
     Centers"  and  "Target  Center"  shall  have the  meaning  set forth in the
     Contribution Agreement, but shall include, upon the acquisition of a Target
     Center  by  Borrower  or any  subsidiary  or  affiliate  of  Borrower,  the
     subsidiary or affiliate utilized to make such acquisition.
                                                    AGREEMENT:

          Borrower has requested from Lender the credit accommodations described
     below, and Lender has agreed to provide such credit  accommodations  on the
     terms and conditions  contained  herein.  Therefore,  for good and valuable
     consideration,  the receipt and  sufficiency  of which  Lender and Borrower
     acknowledge, Lender and Borrower hereby agree as follows:
                                                     ARTICLE I
                                             THE WORKING CAPITAL LOAN

          1.1 The  Working  Capital  Loan.  Lender  agrees to lend and  Borrower
     agrees to  borrow an amount  not to  exceed  the  Working  Capital  Maximum
     Principal Amount on the terms and conditions set forth herein (the "Working
     Capital  Loan").  The Working Capital Loan will be evidenced by the Working
     Capital Note. ------------------------

          1.2  Revolving  Line of Credit.  Subject to and in  reliance  upon the
     terms,  conditions,  representations and warranties  hereinafter set forth,
     Lender agrees to make advances (the "Working Capital Advances") to Borrower
     from  time to  time  during  the  period  from  the  Effective  Date to and
     including the one year  anniversary  of the Effective  Date (the  "Maturity
     Date"),  in an aggregate  amount not to exceed the Working  Capital Maximum
     Principal   Amount.   Each   Working   Capital   Advance   must  be  either
     ------------------------  $10,000 or a higher integral multiple of $10,000.
     Funds  borrowed  and repaid may be  reborrowed,  so long as all  conditions
     precedent to Working  Capital  Advances are met. The purpose of the Working
     Capital  Advances is to provide  funds to Borrower for working  capital and
     for other general business purposes of Borrower.
          1.3 Interest and Repayment.  Borrower  shall pay the aggregate  unpaid
     principal  amount of all Working  Capital  Advances in accordance  with the
     terms of the Working  Capital Note  evidencing the  indebtedness  resulting
     from  such  Working  Capital  Advances.  Interest  on the  Working  Capital
     Advances  shall be due and payable in the manner and at the times set forth
     in the Working  Capital Note,  with final  maturity of the Working  Capital
     Note being on or before the Maturity Date. ----------------------

          1.4 Making Advances. Each Working Capital Advance shall be made within
     two business  days of written  notice (or  telephonic  notice  confirmed in
     writing) given by noon (Austin,  Texas time) on a business day of Lender by
     Borrower to Lender specifying the amount and date thereof (which may be the
     same  business  day) and if sent by wired funds,  at Lender's  option,  the
     wiring  instructions  of the  deposit  account  of  Borrower  to which such
     Working Capital Advance is to be deposited. ---------------

          1.5  Payments  and  Computations.  Borrower  shall  make each  payment
     hereunder and under the Working  Capital Note on the day when due in lawful
     money of the United  States of America to Lender at  Lender's  Address  for
     Payment in same day funds.  All  repayments  of  principal  on the  Working
     Capital Note shall be in a minimum amount of $1,000,  or a higher  integral
     multiple of $1,000. All computations of interest shall be made by Lender on
     the   basis  of  the   actual   number   of  days   (including   the  first
     -------------------------  day but excluding the last day) in the year (365
     or 366,  as the  case  may be)  elapsed,  but in no  event  shall  any such
     computation  result in an amount of interest  that would cause the interest
     contracted for, charged or received by Lender to be in excess of the amount
     that would be payable at the Highest Lawful Rate, as herein defined.
                                                    ARTICLE II
                                          THE DEVELOPMENT FACILITY LOANS

          2.1 The Development Facility. Subject to the terms of the Contribution
     Agreement  and  the  terms,  conditions,   representations  and  warranties
     hereinafter  set forth,  Lender  agrees to lend Borrower from time to time,
     the amounts necessary to acquire or develop Target Centers, in an aggregate
     amount not to exceed the  Development  Facility  Maximum  Principal  Amount
     (collectively, the "Development Facility Loans"). ------------------------

         2.2 Development  Facility Loans.  Each  Development  Facility Loan will
finance  up to 100% of the  purchase  price  (or  development  cost) of a Target
Center being acquired (or developed) by Borrower.  The parties  acknowledge that
the grant of any Development Facility Loan does not create any obligation on the
part of Lender to extend further Development Facility Loans. Additionally,  each
Development  Facility Loan is subject in all respects to Lender  obtaining prior
written  approval from the bank  syndication  under its or its parent  company's
outstanding  borrowing  facilities  and  the  execution  and  delivery  of  such
guarantees by Borrower as may be required by such bank syndication.  Pursuant to
the Contribution Agreement, each Development Facility Loan must be (a) evidenced
by a separate Development Facility Note executed by Borrower, (b) secured by all
of LASIK's  ownership  interest in Borrower as  evidenced by an  Assignment  and
Security  Agreement  executed by LASIK,  and (c)  accompanied  by Assignment and
Security Agreements executed by Borrower. In addition, if Borrower is acquiring,
directly or indirectly, a one hundred percent (100%) interest in a Target Center
(hereinafter  referred to as a "100% Target Center"),  Borrower shall cause such
Target Center to execute a security agreement,  acceptable in form and substance
to  Lender,  granting  to Lender or one of  Lender's  subsidiaries  the  highest
available priority security interest in all of the assets of such Target Center.

          2.3 Interest and  Repayment.  Borrower and Target Center shall pay the
     unpaid principal amount under each Development  Facility Note in accordance
     with the terms of the respective  Development  Facility  Note.  Payments of
     interest and principal on each  Development  Facility Note shall be due and
     payable  in the  manner  and at  the  times  set  forth  in the  respective
     Development Facility Note. ----------------------

                                   ARTICLE III
      CONDITIONS TO WORKING CAPITAL ADVANCES AND DEVELOPMENT FACILITY LOANS

          3.1  Conditions  Precedent to Initial  Working  Capital  Advance.  The
     obligation of Lender to make its initial Working Capital Advance is subject
     to the condition precedent that Lender shall have received on or before the
     day of such  Working  Capital  Advance  the  following,  each  in form  and
     substance satisfactory to Lender and properly executed by Borrower or other
     appropriate  parties:  (a)  the  Working  Capital  Note  duly  executed  by
     Borrower,  and  (b)  such  other  documents,  opinions,   certificates  and
     ------------------------------------------------------- evidences as Lender
     may reasonably request.

          3.2 Conditions  Precedent to Each Working Capital  Advance/Development
     Facility Loan. In addition to the  conditions  precedent  stated  elsewhere
     herein,  Lender shall not be obligated to make any Working  Capital Advance
     or        any        Development        Facility        Loan        unless:

          (a) the  representations  and  warranties  contained in Article IV are
     true and  correct in all  material  respects  on and as of the date of such
     Working Capital Advance or Development Facility Loan, as though made on and
     as of such date with such changes therein;
          (b) on the date of the Working Capital Advance or Development Facility
     Loan,  no Event of Default,  and no event which,  with the lapse of time or
     notice or both,  could  become an Event of  Default,  has  occurred  and is
     continuing;
          (c) there shall have been no material adverse change, as determined by
     Lender in its reasonable  judgment,  in the financial condition or business
     of Borrower;
          (d) there has been no breach or  threatened  breach by Borrower  under
     the  Contribution  Agreement or any  Transaction  Document (as such term is
     defined in the Contribution Agreement);
              with respect to each Development  Facility Loan, Borrower executes
the respective Development Facility Note and Borrower executes an Assignment and
Security  Agreement  in the form  attached  as  Exhibit  G3 to the  Contribution
Agreement,  and  otherwise in form and substance  acceptable  to Lender  wherein
Lender is granted a first lien perfected  security interest in all of Borrower's
or Borrower's  subsidiaries' ownership interest in the Target Center and related
acquisition documents;

              LASIK  shall  have  previously  granted  to  Lender  a first  lien
perfected  security  interest in all of LASIK's  ownership  interest in Borrower
through the execution and delivery of the Assignment  and Security  Agreement in
the form attached as Exhibit G4 to the Contribution Agreement and LASIK shall be
in compliance with all of its obligations thereunder;

          (g) if  Borrower  is using a  Development  Facility  Loan to  acquire,
     directly or  indirectly,  a 100% Target  Center,  Borrower shall cause such
     Target  Center to  execute a  security  agreement,  acceptable  in form and
     substance to Lender, granting to Lender or one of Lender's subsidiaries the
     highest  available  priority security interest in all of the assets of such
     Target Center; and
          (h)  Lender  shall  have  received  such  other  approvals,  opinions,
     documents,  certificates or evidences as Lender may reasonably  request (in
     form and substance reasonably  satisfactory to Lender). Each request for an
     Working  Capital  Advance or  Development  Facility  Loan shall be deemed a
     representation  by Borrower  that the  conditions  of this Section 3.2 have
     been met.
                                                    ARTICLE IV
                                     BORROWER'S REPRESENTATIONS AND WARRANTIES

         Borrower represents and warrants to Lender as follows:

          4.1  Good  Standing.  Borrower  is a  duly  formed  limited  liability
     company,  duly organized and in good  standing,  under the laws of Delaware
     and has the power to own its  property and to carry on its business in each
     jurisdiction in which Borrower operates. -------------

         4.2 Authority and Compliance.  Borrower has full power and authority to
enter into this  Agreement,  to make the  borrowing  hereunder,  to execute  and
deliver  the Loan  Documents  and to incur the  indebtedness  described  in this
Agreement,  all of which has been duly  authorized  by all proper and  necessary
action of its managers and members. No further consent or approval of any public
authority is required as a condition to the validity of any Loan  Document,  and
Borrower is in compliance with all laws and regulatory  requirements to which it
is subject.

          4.3 Binding  Agreement.  This  Agreement and other Loan Documents when
     issued and delivered  pursuant  hereto for value received will  constitute,
     valid and legally binding  obligations of Borrower in accordance with their
     terms. -----------------

          4.4 Litigation.  There are no proceedings pending or, to the knowledge
     of Borrower,  threatened  before any court or  administrative  agency which
     will or may have a material  adverse  effect on the financial  condition or
     operations of Borrower or any subsidiary,  except as disclosed to Lender in
     writing prior to the date of this Agreement.  To the knowledge of Borrower,
     there are no proceedings  pending or threatened  against any Target Center.
     ----------

          4.5 No Conflicting  Agreements.  There are no provisions of Borrower's
     organizational  documents  and no  provisions  of any  existing  agreement,
     mortgage,  indenture  or  contract  binding on Borrower  or  affecting  its
     property,  which would  conflict with or in any way prevent the  execution,
     delivery,   or   carrying   out  of  the  terms  of  the  Loan   Documents.
     -------------------------

          4.6  Ownership  of Assets.  Borrower  will at all times  maintain  its
     tangible property,  real and personal, in good order and repair taking into
     consideration reasonable wear and tear. -------------------

          4.7 Taxes.  All income  taxes and other taxes due and payable  through
     the date of this  Agreement  have been paid prior to  becoming  delinquent.
     -----

                                                     ARTICLE V
                                         BORROWER'S AFFIRMATIVE COVENANTS

         So long as Borrower may borrow under this  Agreement  and until payment
in full of the Working  Capital Note and all  Development  Facility  Notes,  and
performance of all other obligations of Borrower and Target Centers hereunder or
thereunder, Borrower covenants and agrees to do the following:

         5.1      Financial Statements.

                  (a)  Maintain,  and cause each Target  Center to  maintain,  a
         system of  accounting  satisfactory  to Lender and in  accordance  with
         generally accepted accounting principles consistently applied, and will
         permit  Lender's  officers or authorized  representatives  to visit and
         inspect  Borrower's  or  Target  Center's  books of  account  and other
         records  at such  reasonable  times and as often as Lender  may  desire
         during office hours and after  reasonable  notice to Borrower,  and pay
         the  reasonable  fees and  disbursements  of any  accountants  or other
         agents of Lender selected by Lender for the foregoing purposes.  Unless
         written notice of another location is given to Lender, Borrower's books
         and records will be located at Borrower's Address.

          (b) Furnish to Lender year end financial  statements,  of Borrower and
     each Target  Center,  to include  balance  sheet,  operating  statement and
     surplus   reconciliation,   together  with  an  officer's   certificate  of
     compliance with this Agreement  including  computations of all quantitative
     covenants, within 90 days after the end of each annual accounting period.
          (c) Furnish to Lender quarterly financial statements,  of Borrower and
     each Target Center, to include balance sheet and profit and loss statement,
     together with an officer's  certificate  of compliance  with this Agreement
     including computations of all quantitative covenants, within 45 days of the
     end of each such accounting period.
                  (d) With each balance sheet delivered under subsections (b) or
(c) of this Section 5.1, an aging of all Accounts Receivable.

          (e) Promptly provide Lender with such additional information,  reports
     or statements respecting the business operations and financial condition of
     Borrower or any Target Center,  as Lender may reasonably  request from time
     to time.
         5.2  Insurance.  Maintain,  and cause each Target  Center to  maintain,
insurance  with  responsible  insurance  companies  on  such  of its  respective
properties,  in such amounts and against such risks as is customarily maintained
by similar businesses operating in the same vicinity,  specifically to include a
policy  of fire  and  extended  coverage  insurance  covering  all  assets,  and
liability  insurance,  all  to be  with  such  companies  and  in  such  amounts
satisfactory  to Lender and to contain a mortgage  clause  naming  Lender as its
interest may appear. Evidence of such insurance will be supplied to Lender.

          5.3 Existence and Compliance.  Maintain,  and cause each Target Center
     to maintain, its organizational  existence in good standing and comply with
     all laws, regulations and governmental  requirements applicable to it or to
     any of its property, business operations and transactions. Borrower further
     agrees to provide  Lender  with  copies of all  instruments  filed with the
     Delaware Secretary of State amending and/or renewing Borrower's certificate
     of formation. ------------------------

          5.4 Adverse Conditions or Events. Promptly advise Lender in writing of
     any  condition,  event or act which  comes to its  attention  that would or
     might  materially  affect  Borrower's  or  any  Target  Center's  financial
     condition,  Lender's  rights  under  this  Agreement  or any  of  the  Loan
     Documents, and of any litigation filed against Borrower or to its knowledge
     against any Target Center. ----------------------------

         5.5      Taxes.  Pay all taxes as they become due and payable.

          5.6 Maintenance.  Maintain,  and cause each Target Center to maintain,
     all of its  respective  tangible  property  in good  condition  and repair,
     reasonable  wear and tear  excepted,  and make all  necessary  replacements
     thereof,  and preserve and maintain all licenses,  privileges,  franchises,
     certificates  and the like  necessary  for the  operation of its  business.
     -----------

          5.7  Application  of  Earnings.  Except as expressly  contemplated  in
     Section  4.3(e) of the  Contribution  Agreement,  pay all  available  funds
     toward  repayment of the Working Capital Note and any Development  Facility
     Notes,  regardless of whether  payment of such amounts  exceeds the minimum
     required  payments  under  the  Working  Capital  Note and the  Development
     Facility Notes. -----------------------

                                                    ARTICLE VI
                                           BORROWER'S NEGATIVE COVENANTS

         So long as Borrower may borrow under this  Agreement  and until payment
in full of the Working  Capital Note and all  Development  Facility  Notes,  and
performance of all other  obligations of Borrower or Target Center  hereunder or
thereunder, Borrower will not, and will cause each of the Target Centers to not,
without the prior written consent of Lender:

          6.1  Transfer of Assets.  Enter into any merger or  consolidation,  or
     sell, lease,  assign, or otherwise dispose of or transfer any assets except
     in the normal course of its business. ------------------

          6.2 Change in Ownership or Structure.  Dissolve or liquidate; become a
     party  to  any  merger  or  consolidation;  reorganize  as  a  professional
     corporation;  acquire by purchase,  lease or otherwise all or substantially
     all of the assets or capital stock of any  corporation or other entity;  or
     sell, transfer,  lease, or otherwise dispose of all or any substantial part
     of    its     respective     property     or    assets     or     business.
     --------------------------------

          6.3 Liens.  From and after the date hereof  grant,  suffer,  or permit
     liens  on or  security  interests  in its  respective  assets,  or  fail to
     promptly pay all lawful claims, whether for labor, materials, or otherwise,
     except for purchase money security interests arising in the ordinary course
     of its respective business. -----

          6.4 Loans. Make any loans,  advances or investments to or in any joint
     venture,   corporation  or  other  entity,   except  for  the  purchase  of
     obligations  of Lender or U.S.  Government  obligations  or the purchase of
     federally-insured certificates of deposit. -----

          6.5  Borrowings.  Except for  borrowing  or  incurring  open  accounts
     payable to  unaffiliated  third parties in the ordinary course of business,
     create,  incur,  assume,  or liable in any manner for any indebtedness (for
     borrowed  money,  deferred  payment  for  the  purchase  of  assets,  lease
     payments,  as surety or  guarantor  of the debt of another,  or  otherwise)
     other than to Lender in excess of $25,000  without  Lender's  prior written
     consent. ----------

          6.6  Violate  Other  Covenants.  Violate  or fail to  comply  with any
     covenants or agreements  regarding  other debt which will or would with the
     passage of time or upon demand  cause the  maturity of any other debt to be
     accelerated. -----------------------

          6.7 Equity Redemptions or Restructurings. Apply any of its property or
     assets to the  purchase,  retirement  or  redemption  of any of its  equity
     interests    or   in    any    way    amend    its    capital    structure.
     ------------------------------------

          6.8 Character of Business. Change the general character of business as
     conducted  at the  date  hereof,  or  engage  in any type of  business  not
     reasonably  related to its  business as presently  and normally  conducted.
     ---------------------

                                                    ARTICLE VII
                                      EVENTS OF DEFAULT; NOTICE; ACCELERATION

          7.1  Events  of  Default.  If one or more of the  following  events of
     default shall occur and continue  after thirty (30) days' written notice to
     Borrower,  all  outstanding  principal plus unpaid  interest of the Working
     Capital Note and each Development Facility Note, and any other indebtedness
     of Borrower to Lender,  shall  automatically be due and payable immediately
     and Lender shall have no further  obligation to fund under this  Agreement.
     -----------------

          (a) There shall be any breach or default  shall be made in the payment
     of any  installment of principal or interest upon the Working  Capital Note
     or any Development Facility Note, when due and payable, whether at maturity
     or otherwise; or
          (b) There  shall be any  breach or  default  (other  than by Lender or
     Prime Medical  Services,  Inc.) under any Loan Document,  the  Contribution
     Agreement, or any Transaction Document (other than those certain Consulting
     Agreements  with Dr.  Dulaney,  Dr.  Barnet and Mark  Rosenberg as required
     pursuant  to  the  Contribution  Agreement),   or  any  other  certificate,
     agreement or document contemplated hereby or thereby; or
          (c) Any  representation or warranty of Borrower contained herein or in
     any financial statement, certificate, report or opinion submitted to Lender
     in connection  with the Working  Capital Loan or any  Development  Facility
     Loan, or by Borrower pursuant to the requirements of this Agreement,  shall
     prove to have been  incorrect or  misleading  in any material  respect when
     made; or
          (d) Any  judgment  against  Borrower or any  attachment  or other levy
     against  the  property  of  Borrower  with  respect  to a claim  materially
     affecting Borrower's  financial status remains unpaid,  unstayed on appeal,
     undischarged, not bonded or not dismissed for a period of 30 days; or
          (e) The  bankruptcy,  death,  or  dissolution  of any guarantor of the
     Indebtedness; or
                  (f) Borrower makes an assignment for the benefit of creditors,
         admits in writing  its  inability  to pay its debts  generally  as they
         become due, files a petition in bankruptcy, is adjudicated insolvent or
         bankrupt,  petitions or applies to any tribunal for any receiver or any
         trustee  of  Borrower  or any  substantial  part  of  their  respective
         property,   commences  any  action   relating  to  Borrower  under  any
         reorganization,  arrangement,  readjustment  of  debt,  dissolution  or
         liquidation  law  or  statute  of  any  jurisdiction,  whether  now  or
         hereafter in effect, or if there is commenced against Borrower any such
         action,  or Borrower by any act indicates its consent to or approval of
         any trustee for Borrower or any  substantial  part of its property,  or
         suffers any such receivership or trustee to continue undischarged.

         7.2  Lender's  Remedies.  Upon the  occurrence  of an Event of Default,
Lender,  without notice of any kind,  except for any notice  required under this
Agreement or any other Loan Document, may, at Lender's option: (i) terminate its
obligation to fund any Working Capital Advance or any Development  Facility Loan
hereunder;  (ii) declare the Indebtedness,  in whole or in part, immediately due
and payable;  and/or (iii)  exercise any other rights and remedies  available to
Lender under this Agreement, any other Loan Document, or applicable laws; except
that upon the occurrence of an Event of Default described in subsection  7.1(f),
all the Indebtedness  shall  automatically  be immediately due and payable,  and
Lender's  obligation  to fund any  Working  Capital  Advance or any  Development
Facility Loan hereunder  shall  automatically  terminate,  without notice of any
kind (including  without limitation notice of intent to accelerate and notice of
acceleration) to Borrower or to any Target Center,  guarantor,  or to any surety
or endorser of any of the Notes, or to any other person.  Borrower,  each Target
Center,  and each guarantor,  surety,  and endorser of any of the Notes, and any
and all other parties  liable for the  Indebtedness  or any part thereof,  waive
demand,  notice  of  intent  to  demand,  presentment  for  payment,  notice  of
nonpayment,  protest,  notice of protest,  grace, notice of dishonor,  notice of
intent to accelerate maturity, notice of acceleration of maturity, and diligence
in collection.

         7.3 Right of Set-Off. Borrower hereby authorizes Lender, to the maximum
extent permitted under and in accordance with applicable laws, at any time after
the occurrence of an Event of Default which  continues  uncured,  to set-off and
apply  any and all  deposits,  funds or  assets at any time held and any and all
other  indebtedness  at any time  owing by  Lender  to or for the  credit or the
account of  Borrower  against  any and all  Indebtedness,  whether or not Lender
exercises  any  other  right  or  remedy  hereunder  and  whether  or  not  such
Indebtedness are then matured.

                                                   ARTICLE VIII
                                           GENERAL TERMS AND CONDITIONS

         8.1  Notices.  All  notices,  demands,  requests,  approvals  and other
communications  required or permitted hereunder shall be in writing and shall be
deemed to have been given when (a) presented  personally,  or (b) three (3) days
after  deposited in a regularly  maintained mail receptacle of the United States
Postal Service,  postage prepaid,  certified,  return receipt requested,  or (c)
upon receipt of confirmation after sending by facsimile transmission,  addressed
to  Borrower  or  Lender,  as the case may be, at the  respective  addresses  or
facsimile  number for notice set forth on the first page of this  Agreement,  or
such other  address or  facsimile  number as Borrower or Lender may from time to
time designate by written notice to the other.

          8.2 Entire Agreement and Modifications.  The Loan Documents,  together
     with the Contribution Agreement and Transaction  Documents,  constitute the
     entire  understanding and agreement between the undersigned with respect to
     the  transactions  arising in connection  with the Working Capital Loan and
     the  Development  Facility  Loans,  and supersede all prior written or oral
     understandings   and  agreements  between  the  undersigned  in  connection
     therewith.   No   provision   of  this   Agreement   or  the   other   Loan
     ----------------------------------  Documents may be modified,  waived,  or
     terminated  except by instrument  in writing  executed by the party against
     whom a modification,  waiver, or termination is sought to be enforced, and,
     in the case of Lender, executed by a Vice President or higher level officer
     of Lender.
          8.3  Severability.  In case any of the  provisions  of this  Agreement
     shall for any reason be held to be invalid, illegal, or unenforceable, such
     invalidity,  illegality,  or  unenforceability  shall not  affect any other
     provision hereof, and this Agreement shall be construed as if such invalid,
     illegal,  or  unenforceable  provision  had never  been  contained  herein.
     ------------

         8.4  Cumulative  Rights  and No  Waiver.  Lender  shall have all of the
rights and remedies  granted in the Loan  Documents  and  available at law or in
equity,  and these  same  rights and  remedies  shall be  cumulative  and may be
pursued separately,  successively, or concurrently against Borrower, at the sole
discretion of Lender.  Lender's  delay in exercising any right shall not operate
as a waiver thereof,  nor shall any single or partial  exercise by Lender of any
right preclude any other or future exercise thereof or the exercise of any other
right.  Any of Borrower's  covenants and  agreements may be waived by Lender but
only in  writing  signed by an  authorized  officer of Vice  President  level or
higher of Lender or any subsequent  owner or holder of any of the Notes.  Except
as otherwise  expressly  provided in this  Agreement  and in any Note,  Borrower
expressly waives any presentment,  demand, protest, notice of default, notice of
intent  to  accelerate,  notice  of  acceleration,  notice  of  intent to demand
payment,  or other notice of any kind. No notice to or demand on Borrower in any
case shall, of itself, entitle Borrower to any other or further notice or demand
in similar or other circumstances.  No delay or omission by Lender in exercising
any  power  or  right  hereunder  shall  impair  any  such  right or power or be
construed  as a waiver  thereof,  or the  exercise  of any other  right or power
hereunder.

          8.5  Form  and  Substance.  All  documents,  certificates,   insurance
     policies,  and other items  required  under this  Agreement  to be executed
     and/or  delivered  to  Lender  shall  be in form and  substance  reasonably
     satisfactory to Lender. ------------------

         8.6 Limitation on Interest: Maximum Rate. Lender and Borrower intend to
contract in strict  compliance  with  applicable  usury law from time to time in
effect.  To effectuate this intention,  Lender and Borrower  stipulate and agree
that none of the terms and provisions of any Note and any other  agreement among
such parties, whether now existing or arising hereafter, shall ever be construed
as a contract to pay interest for the use,  forbearance or detention of money in
excess of the Maximum Rate. If, from any possible  construction of any document,
interest would otherwise be payable to Lender in excess of the Maximum Rate, any
such  construction  shall be subject to the  provisions of this Section and such
document  shall be  automatically  reformed and the  interest  payable to Lender
shall be  automatically  reduced to the Maximum Rate permitted under  applicable
law,  without the  necessity of the  execution of any amendment or new document.
Neither  Borrower,  endorsers or other persons now or hereafter  becoming liable
for payment of any portion of the  principal  or interest of any Note shall ever
be liable for any  unearned  interest on the  principal  amount or shall ever be
required  to pay  interest  thereon  in excess of the  Maximum  Rate that may be
lawfully  charged under  applicable law from time to time in effect.  Lender and
any subsequent  holder of any Note expressly  disavow any intention to charge or
collect  unearned  or  excessive  interest  or finance  charges in the event the
maturity of any Note, is accelerated. If the maturity of any Note is accelerated
for any reason, whether as a result of a default under any Note, or by voluntary
prepayment,  or otherwise,  any amounts constituting interest, or adjudicated as
constituting  interest,  which  are  then  unearned  and  have  previously  been
collected  by Lender or any  subsequent  holder of any Note  shall be applied to
reduce the principal balance thereof then outstanding, or if such amounts exceed
the unpaid  balance of principal,  the excess shall be refunded to Borrower (and
Target Center,  as applicable).  In the event Lender or any subsequent holder of
any Note ever receives, collects or applies as interest any amounts constituting
interest or adjudicated as constituting  interest which would otherwise increase
the  interest to an amount in excess of the amount  permitted  under  applicable
law,  such amount  which  would be  excessive  interest  shall be applied to the
reduction of the unpaid  principal  balance of such Note,  and, if the principal
balances of such Note is paid in full,  any  remaining  excess  shall be paid to
Borrower (and Target Center, as applicable).  In determining  whether or not the
interest  paid or payable under the specific  contingencies  exceeds the Maximum
Rate allowed by applicable law, Borrower and Lender shall, to the maximum extent
permitted under applicable law, (i) characterize any non-principal payment as an
expense,  fee or  premium,  rather  than as  interest;  (ii)  exclude  voluntary
prepayments  and the effect  thereof;  (iii)  amortize,  prorate,  allocate  and
spread,  in equal  parts,  the total  amount of interest  throughout  the entire
contemplated  term of the applicable Note (as it may be renewed and extended) so
that the interest rate is uniform  throughout  the entire term of such Note. The
terms and  provisions of this section  shall  control and supersede  every other
provision of all existing and future agreements between Lender and Borrower (and
Target Center, as applicable).  As used in this Agreement,  "Maximum Rate" means
the maximum non-usurious interest rate that at any time or from time to time may
be contracted for, taken, reserved,  charged or received on the unpaid principal
or accrued past due interest  under  applicable  law and may be greater than the
applicable  rate,  the parties hereby  stipulating  and agreeing that Lender may
contract for, take,  reserve,  charge or receive interest up to the Maximum Rate
without penalty under any applicable law; and "applicable law" means the laws of
the State of Texas or the laws of the United States of America,  whichever  laws
allow the greater interest,  as such laws now exist or may be changed or amended
or come into effect in the future.  In the event  applicable law provides for an
interest  ceiling under  Chapter One of Title 79, Texas  Revised Civil  Statutes
Annotated, as amended, that ceiling shall be the indicated rate ceiling, subject
to any right  Lender may have in the future to change the method of  determining
the Maximum Rate.

          8.7  Third  Party  Beneficiary.  Borrower  acknowledges  that the bank
     syndication  under the senior credit  facility of Prime  Medical  Services,
     Inc. (as hereinafter supplemented,  modified, or replaced) is a third party
     beneficiary  to this  Agreement.  Except for the preceding  sentence,  this
     Agreement is for the sole benefit of Lender and Borrower and is not for the
     benefit of any third party. -----------------------

          8.8  Borrower  In  Control.  In no event  shall  Lender's  rights  and
     interests  under the Loan  Documents  be construed to give Lender the right
     to, or be deemed to  indicate  that  Lender is in control of the  business,
     management or properties of Borrower or any Target Center or has power over
     the daily management  functions and operating decisions made by Borrower or
     any Target Center. -------------------

          8.9 Use of  Financial  and Other  Information.  Borrower  agrees  that
     Lender shall be permitted to investigate and verify the accuracy of any and
     all information  furnished to Lender in connection with the Loan Documents,
     including without  limitation  financial  statements,  and to disclose such
     information,  or provide  copies of such  information,  to  representatives
     appointed by Lender, including independent accountants,  agents, attorneys,
     asset   investigators,    appraisers   and   any   other   persons   deemed
     --------------------------------------   necessary   by   Lender   to  such
     investigation.
         8.10  Collateral  Assignment of Loan  Documents.  Lender shall have the
right to  collaterally  assign all of its rights  under this  Agreement  and the
other Loan Documents to the third party beneficiaries  described in Section 8.7.
Lender shall have the right to disclose in confidence such financial information
regarding  Borrower as may be  necessary  to  complete  any such  assignment  or
attempted  assignment,  including without limitation,  all financial statements,
projections,  internal memoranda,  audits, reports, payment history,  appraisals
and any and all other  information and  documentation in Lender's files relating
to Borrower.  This  authorization  shall be irrevocable in favor of Lender,  and
Borrower  waives any claims  against Lender or the party  receiving  information
from Lender  regarding  disclosure of information in Lender's files, and further
waive any  alleged  damages  which may  result  from such  disclosure.  Borrower
acknowledges  that Lender intends to make a collateral  assignment of its rights
under this  Agreement  and the Loan  Documents for the benefit of one or more of
its or its  parent  company's  lenders  and will not be  authorized  to amend or
modify this  Agreement  or the Loan  Documents,  or grant  waivers of any of its
rights  thereunder  without  the prior  written  consent  of some or all of such
lenders.

          8.11 Further Assurances.  Borrower agrees to execute and deliver,  and
     cause each Target Center to execute and deliver,  to Lender,  promptly upon
     request from Lender,  such other and further documents as may be reasonably
     necessary  or  appropriate  to  consummate  the  transactions  contemplated
     herein. ------------------

          8.12 Number and Gender.  Whenever  used herein,  the  singular  number
     shall  include the plural and the plural the  singular,  and the use of any
     gender  shall  be  applicable  to  all  genders.  The  duties,   covenants,
     obligations,  and warranties of Borrower in this  Agreement  shall be joint
     and several  obligations of Borrower and of each Borrower if more than one.
     -----------------

          8.13 Captions.  The captions,  headings, and arrangements used in this
     Agreement  are for  convenience  only and do not in any way affect,  limit,
     amplify, or modify the terms and provisions hereof. --------

         8.14  Continuing  Agreement.  This is a  continuing  agreement  and all
rights,  powers,  and remedies of Lender under this Agreement and the other Loan
Documents  shall  continue  in full force and effect  until each Note is paid in
full as the same becomes due and payable and all other  Indebtedness is paid and
discharged, until Lender has no further obligation to advance moneys to Borrower
under this Agreement, and until Lender, upon request of Borrower, has executed a
written termination statement.  Furthermore,  the parties contemplate that there
may be times when no Indebtedness is owing, but notwithstanding such occurrence,
this Agreement (and all other Loan Documents) shall remain valid and shall be in
full force and effect as to subsequent Indebtedness and Advances,  provided that
Lender has not executed a written termination statement.

          8.15  Applicable  Law. This Agreement and the Loan Documents  shall be
     governed by and construed in accordance with the laws of the State of Texas
     and the laws of the United States  applicable to  transactions  within such
     state. --------------

          8.16 NO ORAL  AGREEMENTS.  THE WRITTEN LOAN  AGREEMENT  REPRESENTS THE
     FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
     OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT  ORAL AGREEMENTS OF THE PARTIES.
     THERE   ARE   NO   UNWRITTEN   ORAL   AGREEMENTS   BETWEEN   THE   PARTIES.



                                             [SIGNATURE PAGE FOLLOWS]






<PAGE>




                                                 SIGNATURE PAGE TO
                                                  LOAN AGREEMENT


         EXECUTED as of ____ day of September, 1999.

                                 BORROWER:

                                            PRIME/BDR ACQUISITION, L.L.C.

                                    By:  ______________________________________
                                    Name: ____________________________________
                                    Title: _____________________________________

                                 LENDER:

                                            PRIME MEDICAL OPERATING, INC.

                                    By:  ______________________________________
                                    Name: ____________________________________
                                    Title: _____________________________________





<PAGE>
                                   EXHIBIT-G2

                                 PROMISSORY NOTE
Austin, Texas                   (LINE OF CREDIT)               September 1, 1999



PROMISE TO PAY: For value  received,  the undersigned  Borrower  (whether one or
more) promises to pay to the order of Lender the Principal Amount, to the extent
advanced by Lender, together with interest on the unpaid balance of such amount,
in lawful  money of the United  States of America,  in  accordance  with all the
terms, conditions,  and covenants of this Note and the Loan Documents identified
below.

     BORROWER:  Prime/BDR  Acquisition,  L.L.C.,  a Delaware  limited  liability
company
     BORROWER'S ADDRESS FOR NOTICE:  1301 Capital of Texas Highway,  Suite C-300
Austin, Texas 78746 Attention: President
LENDER:           Prime Medical Operating, Inc., a Delaware corporation

     LENDER'S ADDRESS FOR PAYMENT:  1301 Capital of Texas Highway,  Suite C-300,
Austin, Texas 78746 Attention: Chief Financial Officer
PRINCIPAL AMOUNT:  Two Hundred Thousand Dollars ($200,000)

INTEREST RATE:  Fifteen Percent (15%)

PAYMENT  TERMS:  Interest on the unpaid  balance of this Note is due and payable
quarterly,  beginning  November 1, 1999, and continuing  regularly and quarterly
thereafter on or before the first day of February,  May, August, until September
1, 2000 (the "Maturity  Date"),  when the outstanding  principal balance and all
accrued  interest shall be due and payable in full.  Interest will be calculated
on the unpaid  principal  balance.  Each payment  will be credited  first to the
accrued interest and then to the reduction of principal.

REVOLVING  LINE OF  CREDIT:  This Note  evidences  a  revolving  line of credit.
Subject to the terms of the Loan Agreement  between  Borrower and Lender of even
date  herewith,  all or any portion of the Principal  Amount of this Note may be
borrowed, paid, prepaid, repaid, and reborrowed,  from time to time prior to the
Maturity  Date and in accordance  with the Loan  Documents.  Each  borrowing and
repayment  hereunder will be (i) endorsed on an attachment to this Note, or (ii)
entered  in the books and  records of  Lender.  The books and  records of Lender
shall be prima facie  evidence  of all sums due  Lender.  If an event of default
exists  under  this Note or any Loan  Document,  then  Lender  shall be under no
obligation to make any advance under this Note.

     LOAN  AGREEMENT:  This Note is executed  pursuant to and is governed by the
terms of the Loan  Agreement  of even date  herewith,  executed by Borrower  and
Lender, as amended (collectively, the "Loan Agreement").
1.       INTEREST PROVISIONS:

Rate:  The  principal  balance of this Note from time to time  remaining  unpaid
prior to maturity  shall bear  interest at the  Interest  Rate per annum  stated
above.  Interest  shall be  calculated  on the  amount  of each  advance  of the
Principal Amount of this Note from the date of each such advance.

Maximum  Lawful Interest:  The term "Maximum Lawful Rate" means the maximum rate
         of interest  and the term  "Maximum  Lawful  Amount"  means the maximum
         amount  of  interest  that is  permissible  under  applicable  state or
         federal law for the type of loan  evidenced  by this Note and the other
         Loan  Documents.  If the Maximum Lawful Rate is increased by statute or
         other governmental action subsequent to the date of this Note, then the
         new  Maximum  Lawful  Rate  shall be  applicable  to this Note from the
         effective date thereof, unless otherwise prohibited by applicable law.

Spreadingof Interest:  Because of the possibility of irregular periodic balances
         of principal or premature payment,  the total interest that will accrue
         under this Note cannot be determined in advance. Lender does not intend
         to contract for,  charge,  or receive more than the Maximum Lawful Rate
         or Maximum Lawful Amount  permitted by applicable state or federal law,
         and to prevent such an  occurrence  Lender and Borrower  agree that all
         amounts of interest,  whenever  contracted for, charged, or received by
         Lender, with respect to the loan of money evidenced by this Note, shall
         be spread,  prorated,  or  allocated  over the full period of time this
         Note is unpaid,  including  the period of any renewal or  extension  of
         this Note.  If demand for payment of this Note is made by Lender  prior
         to the full stated term, the total amount of interest  contracted  for,
         charged,  or  received  to the time of such  demand  shall  be  spread,
         prorated, or allocated along with any interest thereafter accruing over
         the full period of time that this Note  thereafter  remains  unpaid for
         the purpose of determining if such interest  exceeds the Maximum Lawful
         Amount.

Excess   Interest:  At maturity  (whether by  acceleration  or  otherwise) or on
         earlier  final  payment of this Note,  Lender  shall  compute the total
         amount of interest that has been contracted for,  charged,  or received
         by Lender or  payable by  Borrower  under  this Note and  compare  such
         amount to the Maximum  Lawful  Amount  that could have been  contracted
         for, charged, or received by Lender. If such computation  reflects that
         the total amount of interest that has been contracted for, charged,  or
         received  by Lender or payable by Borrower  exceeds the Maximum  Lawful
         Amount,  then Lender  shall apply such excess to the  reduction  of the
         principal balance and not to the payment of interest; or if such excess
         interest  exceeds the unpaid  principal  balance,  such excess shall be
         refunded to Borrower. This provision concerning the crediting or refund
         of excess  interest  shall control and take  precedence  over all other
         agreements  between  Borrower and Lender so that under no circumstances
         shall the total interest contracted for, charged, or received by Lender
         exceed the Maximum Lawful Amount.

Interest After Default:  At Lender's option,  the unpaid principal balance shall
         bear interest after maturity  (whether by acceleration or otherwise) at
         the "Default  Interest  Rate." The Default  Interest  Rate shall be, at
         Lender's  option,  (i) the Maximum  Lawful Rate, if such Maximum Lawful
         Rate is established by applicable law; or (ii) the Interest Rate stated
         on the first page of this Note plus five (5) percentage  points,  if no
         Maximum Lawful Rate is established by applicable law; or (iii) eighteen
         percent (18%) per annum; or (iv) such lesser rate of interest as Lender
         in its sole  discretion  may choose to charge;  but never more than the
         Maximum  Lawful Rate or at a rate that would  cause the total  interest
         contracted  for,  charged,  or received by Lender to exceed the Maximum
         Lawful Amount.

Daily Computation of Interest: To the extent permitted by applicable law, Lender
at its option will  calculate  the per diem interest rate or amount based on the
actual  number of days in the year (365 or 366, as the case may be),  and charge
that per diem interest rate or amount each day. In no event shall Lender compute
the interest in a manner that would cause  Lender to contract  for,  charge,  or
receive interest that would exceed the Maximum Lawful Rate or the Maximum Lawful
Amount

DEFAULT PROVISIONS:

EVENTS OF DEFAULT AND  ACCELERATION  OF MATURITY:  LENDER MAY, AFTER THIRTY (30)
DAYS'  WRITTEN  NOTICE TO BORROWER  AND  BORROWER'S  FAILURE TO CURE WITHIN SUCH
30-DAY  PERIOD  AND  WITHOUT  FURTHER  NOTICE OR DEMAND,  (except  as  otherwise
required  by  statute),  ACCELERATE  THE  MATURITY  OF THIS NOTE AND DECLARE THE
ENTIRE UNPAID PRINCIPAL BALANCE AND ALL ACCRUED INTEREST AT ONCE DUE AND PAYABLE
IF:

         There is  default  in the  payment  of any  installment  of  principal,
interest,  or any other sum  required to be paid under the terms of this Note or
any of the Loan Documents; or

         There is a breach or  default  (other  than by Lender or Prime  Medical
Services,  Inc.)  under this Note or any of the Loan  Documents,  including  any
instrument  securing the payment of this Note or any loan agreement  relating to
the advance of loan proceeds.

WAIVER   BY  BORROWER:  EXCEPT AS PROVIDED IN  PARAGRAPH  2(a) HEREOF AND IN ANY
         OTHER LOAN  DOCUMENT,  BORROWER AND ALL OTHER  PARTIES  LIABLE FOR THIS
         NOTE  WAIVE,  DEMAND,  NOTICE  OF  INTENT TO  DEMAND,  PRESENTMENT  FOR
         PAYMENT,  NOTICE OF  NONPAYMENT,  PROTEST,  NOTICE OF  PROTEST,  GRACE,
         NOTICE OF DISHONOR,  NOTICE OF INTENT TO ACCELERATE MATURITY, NOTICE OF
         ACCELERATION  OF MATURITY,  AND  DILIGENCE IN  COLLECTION.  EACH MAKER,
         SURETY,  ENDORSER,  AND GUARANTOR OF THIS NOTE WAIVES AND AGREES TO ONE
         OR MORE  EXTENSIONS  FOR ANY PERIOD OR PERIODS OF TIME, AND ANY PARTIAL
         PAYMENTS, BEFORE OR AFTER MATURITY,  WITHOUT PREJUDICE TO THE HOLDER OF
         THIS NOTE. EACH MAKER, SURETY, ENDORSER, AND GUARANTOR WAIVES NOTICE OF
         ANY AND ALL RENEWALS, EXTENSIONS,  REARRANGEMENTS, AND MODIFICATIONS OF
         THIS NOTE.

Non-Waiver by Lender:  Any previous extension of time,  forbearance,  failure to
pursue some  remedy,  acceptance  of late  payments,  or  acceptance  of partial
payment by Lender,  before or after  maturity,  does not  constitute a waiver by
Lender of its subsequent  right to strictly  enforce the collection of this Note
according to its terms.

Other  Remedies Not  Required:  Lender shall not be required to first file suit,
exhaust all  remedies,  or enforce its rights  against any  security in order to
enforce payment of this Note.

Joint and Several  Liability:  Each Borrower who signs this Note, and all of the
other  parties  liable  for the  payment  of  this  Note,  such  as  guarantors,
endorsers,  and sureties,  are jointly and  severally  liable for the payment of
this Note.

Attorney's  Fees: If Lender  requires the services of an attorney to enforce the
payment of this Note or the performance of the other Loan Documents,  or if this
Note is collected through any lawsuit,  probate,  bankruptcy,  or other judicial
proceeding,  Borrower  agrees to pay  Lender an amount  equal to its  reasonable
attorney's fees and other collection  costs.  This provision shall be limited by
any applicable statutory  restrictions  relating to the collection of attorney's
fees.

3.       MISCELLANEOUS PROVISIONS:

Subsequent Holder: All references to Lender in this Note shall also refer to any
subsequent owner or holder of this Note by transfer, assignment, endorsement, or
otherwise.

Transfer:Borrower  acknowledges and agrees that Lender may transfer this Note or
         partial   interests  in  the  Note  to  one  or  more   transferees  or
         participants,  including without  limitation  transfers provided for in
         Section  8.10 of the Loan  Agreement.  Borrower  authorizes  Lender  to
         disseminate  to any  such  transferee  or  participant  or  prospective
         transferee or participant any information it has pertaining to the loan
         evidenced  by  this  Note,   including,   without  limitation,   credit
         information  on Borrower and any  guarantor of this Note and any of the
         type of information described in Section 8.10 of the Loan Agreement.

Other  Parties  Liable:  All  promises,  waivers,   agreements,  and  conditions
applicable  to Borrower  shall  likewise be  applicable  to and binding upon any
other  parties  primarily  or  secondarily  liable for the payment of this Note,
including all guarantors, endorsers, and sureties.

Successors  and Assigns:  The  provisions of this Note shall be binding upon and
for the benefit of the successors, assigns, heirs, executors, and administrators
of Lender and Borrower.

No Duty or Special  Relationship:  Borrower acknowledges that Lender has no duty
of good faith to Borrower,  and Borrower acknowledges that no fiduciary,  trust,
or other special relationship exists between Lender and Borrower.

Modifications:  Any modifications agreed to by Lender relating to the release of
liability of any of the parties primarily or secondarily  liable for the payment
of this Note, or relating to the release,  substitution, or subordination of all
or part of the security for this Note,  shall in no way  constitute a release of
liability  with  respect to the other  parties or  security  not covered by such
modification.

Entire  Agreement:  Borrower  warrants and  represents  that the Loan  Documents
constitute the entire agreement  between Borrower and Lender with respect to the
loan  evidenced  by this Note and agrees  that no  modification,  amendment,  or
additional  agreement  with  respect  to such loan or the  advancement  of funds
thereunder will be valid and  enforceable  unless made in writing signed by both
Borrower and Lender.

Borrower's  Address  for Notice:  All  notices  required to be sent by Lender to
Borrower shall be sent by U.S. Mail, postage prepaid,  to Borrower's Address for
Notice stated on the first page of this Note, until Lender shall receive written
notification from Borrower of a new address for notice.

Lender's  Address for  Payment:  All sums payable by Borrower to Lender shall be
paid at Lender's  Address for Payment  stated on the first page of this Note, or
at such other address as Lender shall designate from time to time.

Business Use:  Borrower  warrants and  represents to Lender that the proceeds of
this Note will be used solely for business or commercial purposes, and in no way
will the proceeds be used for personal, family, or household purposes.

Chapter 15 Not Applicable:  It is understood that Chapter 15 of the Texas Credit
Code relating to certain  revolving credit loan accounts and tri-party  accounts
is not applicable to this Note.

APPLICABLE  LAW: THIS NOTE HAS BEEN EXECUTED AND DELIVERED IN TEXAS AND SHALL BE
CONSTRUED IN ACCORDANCE  WITH THE APPLICABLE  LAWS OF THE STATE OF TEXAS AND THE
LAWS OF THE UNITED STATES OF AMERICA APPLICABLE TO TRANSACTIONS IN TEXAS.

4.       LOAN DOCUMENTS:

This Note.

The Loan Agreement and the Loan Documents as defined therein.

All      other  documents  signed in connection  with the Loan  Agreement or the
         loan  evidenced  by this  Note,  including,  without  limitation,  that
         certain  Contribution  Agreement,  dated  effective  September 1, 1999,
         between and among Borrower,  Lender,  Prime Medical  Services,  Inc., a
         Delaware  corporation,   Prime/BDEC  Acquisition,  L.L.C.,  a  Delaware
         limited  liability  company,  Barnet Dulaney Eye Center,  P.L.L.C.,  an
         Arizona  professional  limited  liability  company,   LASIK  Investors,
         L.L.C., a Delaware limited liability company,  David D. Dulaney,  M.D.,
         Ronald  W.  Barnet,   M.D.,  and  Mark  Rosenberg  (the   "Contribution
         Agreement") and each  Transaction  Document (as such term is defined in
         the Contribution Agreement).

                                              [Signature page follows]



<PAGE>


                                                  SIGNATURE PAGE TO
                                                   PROMISSORY NOTE


EXECUTED this ____ day of September, 1999.



                 BORROWER:

             PRIME/BDR ACQUISITION, L.L.C., a Delaware limited liability company



                                  By: ________________________________________

                                  Printed Name: _______________________________

                                  Title: _______________________________________



<PAGE>
                                   EXHIBIT G3

                                     FORM OF

                        ASSIGNMENT AND SECURITY AGREEMENT

         THIS ASSIGNMENT AND SECURITY  AGREEMENT (this  "Agreement") is made and
entered  into as of the ____  day of  __________,  1999,  by and  between  Prime
Medical  Operating,  Inc.,  a Delaware  corporation  (the  "Secured  Party") and
Prime/BDR  Acquisition,  L.L.C.,  a  Delaware  limited  liability  company  (the
"Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Contribution  Agreement  dated  effective  September 1, 1999,  between and among
Debtor,  Secured Party,  Prime Medical Services,  Inc., a Delaware  corporation,
Prime/BDEC  Acquisition,  L.L.C., a Delaware limited liability  company,  Barnet
Dulaney Eye Center, P.L.L.C., an Arizona professional limited liability company,
LASIK Investors L.L.C., a Delaware limited liability company,  David D. Dulaney,
M.D., Ronald W. Barnet, M.D., and Mark Rosenberg (the "Contribution Agreement"),
and  that  certain  Loan  Agreement,   dated  September  ___,  1999  (the  "Loan
Agreement"),  pursuant to which  Secured  Party agrees to make certain  loans to
Debtor on the terms and subject to the conditions provided therein.

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or  hereafter  have  to  Secured  Party,  including,   without  limitation,  any
obligations arising under loans made pursuant to the Loan Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured Party's extension of credit under the Loan Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

     (a) Interest in  Subsidiary.  All ownership  interests of Debtor in [Target
Center],  whether now existing or  hereafter  acquired  and  including,  without
limitation, that certain ____% interest in [Target Center]

     (b) Interest in Acquisition Agreements. All of Debtor's interest and rights
(but not any obligations)  under that certain  [Describe  Acquisition  Documents
Pursuant To Which Target Center Was Acquired and Related Transaction Documents];

                  (c)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable  to any of the  Collateral  described in (a) and (b)above,  and all
rights of Debtor now or hereafter arising under any agreement  pertaining to the
Collateral  described in (a) and (b) above,  including  without  limitation  all
distributions,   proceeds,  fees,  dividends,  preferences,  payments  or  other
benefits of whatever nature which Debtor is now or may hereafter become entitled
to receive with respect to any Collateral described in (a) and (b) above;

                  (d) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive  or shall  receive  in  connection  with any other
Collateral:  (i) any stock or other  ownership  certificate,  including  without
limitation,  any certificate representing a stock dividend or any certificate in
connection with any recapitalization,  reclassification,  merger, consolidation,
conversion,  sale of assets,  combination,  stock split, reverse stock split, or
spin-off;  (ii) any  option,  warrant,  subscription  or  right,  whether  as an
addition to or in substitution of any other  Collateral;  (iii) any dividends or
distributions  of any kind whatsoever,  whether  distributable in cash, stock or
other property;  (iv) any interest,  premium or principal payments;  and (v) any
conversion or redemption proceeds; and

                  (e) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral described in (a), (b), (c) or (d) above, including without limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
or  any  subsidiary  of  Secured  Party  (including,   without  limitation,  any
principal,  interest,  fees and other amounts,  and any other obligations) under
and  pursuant to this  Agreement  and/or the  Contribution  Agreement,  the Loan
Agreement,   each   promissory  note  issued  pursuant  to  the  Loan  Agreement
(collectively,  the  "Note"),  and/or any other  contract or  agreement  between
Secured Party (or any of its subsidiaries) and Debtor or any affiliate of Debtor
(collectively,  including the Contribution Agreement, the Loan Agreement and the
Note, the "Other Agreements"); and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor  and/or any  affiliate of Debtor to Secured  Party or any  subsidiary  of
Secured  Party of any kind or  character,  now  existing or  hereafter  arising,
whether direct, indirect,  related,  unrelated,  fixed, contingent,  liquidated,
unliquidated, joint, several or joint and several, arising from, connected with,
or  related  to the Other  Agreements,  or any  other  document,  agreement,  or
instrument  executed  in  connection  therewith,  (ii) all  accrued  but  unpaid
interest  on  any  of  the  indebtedness  described  in  (i)  above,  (iii)  all
obligations  of Debtor  and/or any  affiliate of Debtor to Secured  Party or any
subsidiary  of Secured  Party  under any  documents  or  agreements  evidencing,
securing,  governing  and/or  pertaining to all or any part of the  indebtedness
described in (i) and (ii) above, (iv) all costs and expenses incurred by Secured
Party or its  subsidiaries in connection with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party or any  subsidiary  of Secured Party to Debtor or any affiliate of Debtor,
or expended by Secured  Party or its  subsidiaries  for the account of Debtor or
its  affiliates or otherwise  owing by Debtor or its affiliates to Secured Party
or its subsidiaries,  in respect of the Obligations, and all other sums expended
or  advanced  by  Secured  Party  or its  subsidiaries  pursuant  to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

         Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3 No  Agreements.  The  Interests  are not  subject  to any  right of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is and will
be solvent;  (ii) the fair saleable  value of Debtor's  assets  exceeds and will
continue  to exceed  Debtor's  liabilities  (both fixed and  contingent);  (iii)
Debtor  has  and  will  have  sufficient  capital  to  satisfy  all of  Debtor's
obligations as they become due; (iv) no receiver, trustee, or custodian has been
appointed for, or taken possession of, all or substantially all of the assets of
Debtor,  either in a  proceeding  brought by Debtor or in a  proceeding  brought
against Debtor; (v) Debtor is not the subject of a petition for relief under the
United States  Bankruptcy Code or any similar  federal or state  insolvency law,
including without limitation a petition filed by Debtor or a petition filed by a
third party seeking relief against  Debtor;  and (vi) Debtor has no intention of
filing a petition  for relief  under the United  States  Bankruptcy  Code or any
similar  federal  or state  insolvency  law,  or of  seeking  any other  form of
creditor relief,  within the two-year period  immediately  following the date of
this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform  its  obligations  under each  Other  Agreement.  No further  consent or
approval is required as a condition  to the  validity of this  Agreement  or any
Other Agreement.  Debtor is in compliance with all applicable laws,  ordinances,
statutes, orders, regulations,  judgments, writs, or decrees of any governmental
entity to which it is subject.

         3.3  Binding  Agreement.   This  Agreement  and  each  Other  Agreement
constitute valid and legally binding  obligations of Debtor,  in accordance with
their terms, subject to the applicable bankruptcy,  insolvency,  reorganization,
moratorium, and similar laws affecting creditors' rights generally.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's  ability to perform its  obligations  under this Agreement or any Other
Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
interests  or  shares  of any  class  of  securities  of such  issuer,  (ii) any
instrument  convertible  voluntarily by the holder thereof or automatically upon
the occurrence or non-occurrence of any event or condition into, or exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding the Interests  unless  consented to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees  that it shall  (i)  promptly  advise  Secured  Party in  writing  of any
litigation  filed against Debtor and of any condition,  event or act which comes
to its attention that would or might have a material  adverse effect on Debtor's
financial  condition  or on Debtor's  ability to perform the  Obligations,  (ii)
except  as  expressly   contemplated  in  Section  4.3(e)(i)  and  (ii)  of  the
Contribution  Agreement,  pay all available funds toward  repayment of the Note,
regardless  of whether  payment of such amounts  exceeds the  required  payments
under  the Note and  (iii) if  Borrower  uses any  proceeds  from the  Note,  to
acquire,  directly or indirectly,  a one hundred  percent  (100%)  interest in a
Target  Center,  Borrower  shall cause such Target  Center to execute a security
agreement, acceptable in form and substance to Lender, granting to Lender or one
of Lender's subsidiaries the highest available priority security interest in all
of the assets of such Target Center.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:


                  (a) The  failure  of Debtor to pay any amount  required  to be
paid  under  the  Loan  Agreement  (including,  without  limitation,  principal,
interest and fees due  thereunder),  or any other amount which Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
ten (10) calendar days after such amount is due;

                  (b) The  failure  of Debtor to pay any  Obligation  after such
amount is due (and, if applicable  under the terms of any contractual  agreement
creating or governing such  Obligation,  after the expiration of any cure period
expressly required);

     (c) Debtor's breach of a covenant in this Agreement or any other failure to
perform its obligations under this Agreement or any Other Agreement;

                  (d) Any  representation  or  warranty  made by  Debtor in this
Agreement or any Other Agreement between Debtor and Secured Party shall be false
or materially misleading,  as determined in the reasonable discretion of Secured
Party;

                  (e) Any event of default  shall  occur  under the terms of the
Loan  Agreement  and shall not be cured within the time  expressly  provided for
with respect thereto in the Loan Agreement;

                  (f) If Debtor or any other party  obligated to pay any portion
of the  Obligations:  (i)  becomes  insolvent,  or makes a transfer  in fraud of
creditors,  or makes an assignment  for the benefit of  creditors,  or admits in
writing its inability to pay its debts as they become due; (ii) generally is not
paying its debts as such debts  become due and  Secured  Party,  in good  faith,
determines that such event or condition  could lead to a material  impairment of
the Collateral, or any part thereof, or of any other payment security for any of
the Obligations;  (iii) has a receiver,  trustee or custodian  appointed for, or
take possession of, all or substantially  all of the assets of such party or any
of the  Collateral,  either  in a  proceeding  brought  by  such  party  or in a
proceeding  brought against such party and such appointment is not discharged or
such  possession  is not  terminated  within sixty (60) days after the effective
date thereof or such party  consents to or  acquiesces  in such  appointment  or
possession;  (iv) files a petition for relief under the United States Bankruptcy
Code or any other present or future federal or state  insolvency,  bankruptcy or
similar laws (all of the foregoing  hereinafter  collectively called "Applicable
Bankruptcy  Law") or an  involuntary  petition for relief is filed  against such
party under any Applicable  Bankruptcy Law and such involuntary  petition is not
dismissed  within  sixty  (60) days after the  filing  thereof,  or an order for
relief naming such party is entered under any Applicable  Bankruptcy Law, or any
composition, rearrangement, extension, reorganization or other relief of debtors
now or hereafter  existing is requested or consented to by such party; (v) fails
to  have  discharged  within  a  period  of  sixty  (60)  days  any  attachment,
sequestration  or similar writ levied upon,  or any claim  against or affecting,
any  property  of such party;  or (vi) fails to pay within  ninety (90) days any
final money judgment against such party; or

                  (g) The issuer of any securities constituting Collateral files
a petition  for relief  under any  Applicable  Bankruptcy  Law,  an  involuntary
petition  for  relief is filed  against  any such  issuer  under any  Applicable
Bankruptcy Law and such involuntary petition is not dismissed within thirty (30)
days after the filing thereof,  or an order for relief naming any such issuer is
entered under any Applicable Bankruptcy Law.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (c) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (d) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in any type of offering  which  complies  with, or is exempt from the
registration  requirements  of, the  Securities  Act of 1933 and any  applicable
state  securities laws, and no sale so made in good faith by Secured Party shall
be deemed to be not "commercially reasonable" because so made.

                  (e)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the  Contribution  Agreement or any
Other  Agreement;  (d)  then,  to or among the  amounts  of fees,  interest  and
principal then owing and unpaid in respect of the Obligations,  in such priority
as Secured Party may determine in its discretion;  and (e) the remainder of such
proceeds,  if  any,  shall  be  paid  to  Debtor.  If  such  proceeds  shall  be
insufficient to discharge the entire  Obligations,  Secured Party shall have any
other available legal recourse  against Debtor under, or for the performance of,
the  Contribution  Agreement and any Other Agreement  between Debtor and Secured
Party,  for the deficiency,  together with interest  thereon at the maximum rate
permitted under applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of any Other Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY, PROTECT, DEFEND AND HOLD HARMLESS SECURED PARTY AND ITS
SUBSIDIARIES,  AND EACH OF THEIR OFFICERS, DIRECTORS,  REPRESENTATIVES,  AGENTS,
EMPLOYEES,  LENDERS,  SUCCESSORS AND ASSIGNS,  FROM AND AGAINST ALL LIABILITIES,
CLAIMS, DAMAGES,  LOSSES, FINES, PENALTIES,  CAUSES OF ACTIONS, SUITS, JUDGMENTS
AND EXPENSES (INCLUDING COURT COSTS,  ATTORNEY'S FEES AND COST OF INVESTIGATION)
OF ANY  NATURE,  KIND OR  DESCRIPTION  OF ANY  PERSON  OR  ENTITY,  DIRECTLY  OR
INDIRECTLY,  ARISING OUT OF, CAUSED BY OR RESULTING  FROM (IN WHOLE OR IN PART),
ANY ACT OR  OMISSION  OF SECURED  PARTY,  OR ANYONE  ACTING ON BEHALF OF SECURED
PARTY,  IN CONNECTION  WITH THE  COLLATERAL,  INCLUDING  WITHOUT  LIMITATION ANY
MARKET FLUCTUATIONS IN THE COLLATERAL AS A RESULT OF SECURED PARTY'S SALE OF, OR
FAILURE TO SELL, THE INTERESTS AT ANY  PARTICULAR  TIME WHEN IT HAS THE RIGHT TO
DO  SO.  THE  FOREGOING  INDEMNITY  SHALL  SURVIVE  THE  EXPIRATION  OR  EARLIER
TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed and observed by Debtor under any Other Agreement,  or in respect
of the Collateral (subject to any applicable default cure period), Secured Party
(a) may but  shall not be  obligated  to take any  action  Secured  Party  deems
necessary  or  desirable  to  prevent  or remedy  any such  default by Debtor or
otherwise to protect the Security Interest,  and (b) shall have the absolute and
immediate right to take possession of the Collateral or any part thereof (to the
extent Secured Party has not previously taken  possession) to such extent and as
often as the Secured Party, in its sole discretion, deems necessary or desirable
in order to prevent  or to cure any such  default by  Debtor,  or  otherwise  to
protect the security of this Agreement. Secured Party may advance or expend such
sums of money for the account of Debtor as Secured Party in its sole  discretion
deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become  involved  by reason of or  arising  out of any  Other  Agreement  or the
Collateral,  shall be a part of the  Obligations  and shall be paid by Debtor to
Secured  Party,  upon demand,  and shall bear interest until paid at the maximum
rate of interest  permitted by applicable law, from the date incurred by Secured
Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:       1301 Capital of Texas Hwy., Suite C-300
                                       Austin, Travis County, Texas 78746
                                       Attn: President

                  with copy to:        Timothy L. LaFrey, Esq.
                                       Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                       1900 Frost Bank Plaza
                                       816 Congress Avenue
                                       Austin, Texas 78701

                  Debtor:              Prime/BDR Acquisition, L.L.C.
                                       1301 Capital of Texas Hwy., Suite C-300
                                       Austin, Travis County, Texas 78746
                                       Attn: President

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval  or  consent.  Debtor  acknowledges  that  Lender  intends  to  make  a
collateral  assignment of its rights under this Agreement for the benefit of one
or more of its  lenders.  Debtor may not  assign  this  Agreement  or any of its
rights or  obligations  hereunder  without the express prior written  consent of
Secured Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT. THIS AGREEMENT, THE LOAN AGREEMENT, THE NOTE AND THE
CONTRIBUTION AGREEMENT REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY
NOT BE  CONTRADICTED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL
AGREEMENTS OF THE PARTIES.  THERE ARE NO UNWRITTEN ORAL  AGREEMENTS  BETWEEN THE
PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this ____ day of __________, 1999.


DEBTOR:                                    Prime/BDR Acquisition, L.L.C.

                                           By:_________________________________

                                           Printed Name:________________________

                                           Title:_______________________________


SECURED PARTY:                             Prime Medical Operating, Inc.

                                           By:_________________________________

                                           Printed Name:________________________

                                           Title:_______________________________



<PAGE>
                                   EXHIBIT-G4

                                         ASSIGNMENT AND SECURITY AGREEMENT

         THIS ASSIGNMENT AND SECURITY  AGREEMENT (this  "Agreement") is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating,  Inc., a Delaware  corporation  (the  "Secured  Party") and Prime/BDR
Acquisition, L.L.C., a Delaware limited liability company (the "Debtor").

                                                     RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Contribution  Agreement  dated  effective  September 1, 1999,  between and among
Debtor,  Secured Party,  Prime Medical Services,  Inc., a Delaware  corporation,
Prime/BDEC  Acquisition,  L.L.C., a Delaware limited liability  company,  Barnet
Dulaney Eye Center, P.L.L.C., an Arizona professional limited liability company,
LASIK Investors L.L.C., a Delaware limited liability company,  David D. Dulaney,
M.D., Ronald W. Barnet, M.D., and Mark Rosenberg (the "Contribution Agreement"),
and that certain Loan Agreement, dated September 1, 1999 (the "Loan Agreement"),
pursuant to which  Secured  Party agrees to make certain  loans to Debtor on the
terms and subject to the conditions provided therein.

          B. Secured Party has requested  that Debtor pledge the  Collateral (as
     defined below) to secure certain  obligations and  liabilities  that Debtor
     may now or hereafter have to Secured Party, including,  without limitation,
     any obligations arising under loans made pursuant to the Loan Agreement.

         C. Debtor desires to enter into this Agreement as a material inducement
to Secured Party's extension of credit under the Loan Agreement.

                                                    AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                                     ARTICLE I
                                        COLLATERAL AND SECURED OBLIGATIONS

          1.1 Grant of Security Interest. Debtor hereby assigns,  transfers, and
     pledges  to Secured  Party,  and Debtor  hereby  grants to Secured  Party a
     security interest in, the following described collateral (collectively, the
     "Collateral"): --------------------------

          (a)  Interest in  Subsidiary.  All  ownership  interests  of Debtor in
     Horizon Vision Center, Inc., a Nevada corporation ("Horizon"),  whether now
     existing or hereafter  acquired and  including,  without  limitation,  that
     certain 60% interest in Horizon (the "Interests"). ----------------------



<PAGE>



          (b) Interest in Acquisition  Agreements.  All of Debtor's interest and
     rights  (but  not any  obligations)  under  those  certain  Stock  Purchase
     Agreements  by  and  between  Debtor  and  the   Shareholders  of  Horizon;
     ----------------------------------

          (c) Accounts. All accounts and rights now or hereafter attributable to
     any of the  Collateral  described  in (a) and  (b)above,  and all rights of
     Debtor now or  hereafter  arising  under any  agreement  pertaining  to the
     Collateral described in (a) and (b) above, including without limitation all
     distributions,  proceeds, fees, dividends,  preferences,  payments or other
     benefits of whatever  nature  which Debtor is now or may  hereafter  become
     entitled to receive with respect to any Collateral --------described in (a)
     and (b) above;

                  (d) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive  or shall  receive  in  connection  with any other
Collateral:  (i) any stock or other  ownership  certificate,  including  without
limitation,  any certificate representing a stock dividend or any certificate in
connection with any recapitalization,  reclassification,  merger, consolidation,
conversion,  sale of assets,  combination,  stock split, reverse stock split, or
spin-off;  (ii) any  option,  warrant,  subscription  or  right,  whether  as an
addition to or in substitution of any other  Collateral;  (iii) any dividends or
distributions  of any kind whatsoever,  whether  distributable in cash, stock or
other property;  (iv) any interest,  premium or principal payments;  and (v) any
conversion or redemption proceeds; and

          (e)  Proceeds.  All proceeds  (cash and  non-cash)  arising out of the
     sale,  exchange,  collection or other  disposition of all or any portion of
     the Collateral  described in (a), (b), (c) or (d) above,  including without
     limitation  proceeds  in  the  form  of  stock,  accounts,  chattel  paper,
     instruments, documents, goods, inventory and equipment. --------

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

          1.2 Obligations. This Agreement and the Security Interest shall secure
     full and punctual  payment and  performance of the following  indebtedness,
     duties and obligations (collectively, the "Obligations"): -----------

                  (a) All liabilities and obligations of Debtor to Secured Party
or  any  subsidiary  of  Secured  Party  (including,   without  limitation,  any
principal,  interest,  fees and other amounts,  and any other obligations) under
and  pursuant to this  Agreement  and/or the  Contribution  Agreement,  the Loan
Agreement,   each   promissory  note  issued  pursuant  to  the  Loan  Agreement
(collectively,  the  "Note"),  and/or any other  contract or  agreement  between
Secured Party (or any of its subsidiaries) and Debtor or any affiliate of Debtor
(collectively,  including the Contribution Agreement, the Loan Agreement and the
Note, the "Other Agreements"); and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor  and/or any  affiliate of Debtor to Secured  Party or any  subsidiary  of
Secured  Party of any kind or  character,  now  existing or  hereafter  arising,
whether direct, indirect,  related,  unrelated,  fixed, contingent,  liquidated,
unliquidated, joint, several or joint and several, arising from, connected with,
or  related  to the Other  Agreements,  or any  other  document,  agreement,  or
instrument  executed  in  connection  therewith,  (ii) all  accrued  but  unpaid
interest  on  any  of  the  indebtedness  described  in  (i)  above,  (iii)  all
obligations  of Debtor  and/or any  affiliate of Debtor to Secured  Party or any
subsidiary  of Secured  Party  under any  documents  or  agreements  evidencing,
securing,  governing  and/or  pertaining to all or any part of the  indebtedness
described in (i) and (ii) above, (iv) all costs and expenses incurred by Secured
Party or its  subsidiaries in connection with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party or any  subsidiary  of Secured Party to Debtor or any affiliate of Debtor,
or expended by Secured  Party or its  subsidiaries  for the account of Debtor or
its  affiliates or otherwise  owing by Debtor or its affiliates to Secured Party
or its subsidiaries,  in respect of the Obligations, and all other sums expended
or  advanced  by  Secured  Party  or its  subsidiaries  pursuant  to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II
       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

         Debtor hereby represents and warrants to Secured Party as follows:

          2.1 Ownership of Collateral.  Debtor has good and marketable  title to
     the  Collateral   free  and  clear  of  any  liens,   security   interests,
     shareholders  agreement,  calls,  charge,  or encumbrance,  except for this
     Security  Interest.  No financing  statement or other instrument similar in
     effect  covering  all or any  part  of the  Collateral  is on  file  in any
     recording  office,  except as may have been filed in favor of Secured Party
     relating to this Agreement. -----------------------

          2.2  Power &  Authority.  Debtor  has the  lawful  right,  power,  and
     authority to grant the Security Interest in the Collateral. This Agreement,
     together  with all filings and other  actions  necessary  or  desirable  to
     perfect and protect  such  security  interest,  which have been duly taken,
     create a valid  and  perfected  first  priority  security  interest  in the
     Collateral  securing  the  payment  and  performance  of  the  Obligations.
     -----------------

          2.3 No  Agreements.  The  Interests  are not  subject  to any right of
     redemption,  or any call or put options, voting trust, proxy,  shareholders
     agreement, right of first refusal, or any other document or agreement which
     would in any way impair or adversely  affect this Security  Interest or the
     rights of Secured Party under this Agreement. -------------

          2.4 Securities.  Any  certificates  evidencing  securities  pledged as
     Collateral are valid and genuine and have not been altered.  All securities
     pledged as Collateral  have been duly  authorized and validly  issued,  are
     fully  paid and  non-assessable,  and were not issued in  violation  of the
     preemptive  rights of any party or of any  agreement by which Debtor or the
     issuer thereof is bound. No  restrictions or conditions  exist with respect
     to  the  transfer  or  voting  of  any  securities  pledged  as  ----------
     Collateral.

                                                    ARTICLE III
                                   DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is and will
be solvent;  (ii) the fair saleable  value of Debtor's  assets  exceeds and will
continue  to exceed  Debtor's  liabilities  (both fixed and  contingent);  (iii)
Debtor  has  and  will  have  sufficient  capital  to  satisfy  all of  Debtor's
obligations as they become due; (iv) no receiver, trustee, or custodian has been
appointed for, or taken possession of, all or substantially all of the assets of
Debtor,  either in a  proceeding  brought by Debtor or in a  proceeding  brought
against Debtor; (v) Debtor is not the subject of a petition for relief under the
United States  Bankruptcy Code or any similar  federal or state  insolvency law,
including without limitation a petition filed by Debtor or a petition filed by a
third party seeking relief against  Debtor;  and (vi) Debtor has no intention of
filing a petition  for relief  under the United  States  Bankruptcy  Code or any
similar  federal  or state  insolvency  law,  or of  seeking  any other  form of
creditor relief,  within the two-year period  immediately  following the date of
this Agreement.

          3.2 Authority and  Compliance.  Debtor has full power and authority to
     enter into this  Agreement.  Debtor has full power and  authority  to enter
     into and perform its  obligations  under each Other  Agreement.  No further
     consent or approval is  required  as a  condition  to the  validity of this
     Agreement  or  any  Other  Agreement.  Debtor  is in  compliance  with  all
     applicable laws,  ordinances,  statutes,  orders,  regulations,  judgments,
     writs,  or  decrees  of any  governmental  entity  to which it is  subject.
     ------------------------

          3.3  Binding  Agreement.  This  Agreement  and  each  Other  Agreement
     constitute valid and legally binding  obligations of Debtor,  in accordance
     with  their  terms,  subject  to  the  applicable  bankruptcy,  insolvency,
     reorganization,  moratorium,  and similar laws affecting  creditors' rights
     generally. -----------------

          3.4 Litigation.  There are no proceedings pending or, to the knowledge
     of Debtor,  threatened before any court or administrative agency which will
     or may have a material adverse effect on the financial  condition of Debtor
     or upon Debtor's ability to perform its obligations under this Agreement or
     any Other Agreement. ----------

          3.5 No Conflicting Agreements. There are no provisions of any existing
     agreement,  mortgage,  indenture or contract binding on Debtor or affecting
     its  property,  which  would  conflict  with  or in  any  way  prevent  the
     execution,  delivery, or carrying out of the terms of this Agreement or any
     Other Agreement. -------------------------

          3.6  Ownership  of  Assets.  Debtor  has good  and  full  title to the
     Collateral,  and the Collateral is owned free and clear of liens,  charges,
     claims, security interests, and other encumbrances. -------------------

          3.7 Taxes.  Debtor has filed all tax  returns  required to be filed by
     Debtor.
                                                    ARTICLE IV
                                   DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(d)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

          4.5 Liens.  Neither  Debtor nor any person  acting on Debtor's  behalf
     has, or shall have any right,  power, or authority to and shall not create,
     incur, or permit to be placed or imposed, upon the Collateral,  any lien of
     any type or nature  whatsoever,  other  than the liens in favor of  Secured
     Party. -----

          4.6 Matters or  Occurrences  Affecting  Collateral or this  Agreement.
     Debtor  will  promptly  notify  Secured  Party  of any and all  matters  or
     occurrences  that may have a material adverse effect on the status or value
     of the  Collateral or this  Agreement,  including  without  limitation  the
     occurrence of an Event of Default, or an event which, with giving of notice
     or  lapse  of  time,  or  both,  would  constitute  an  Event  of  Default.
     -------------------------------------------------------------

          4.7 Agreements  Pertaining to  Collateral.  Debtor will not enter into
     any type of contract or agreement pertaining to any of the Collateral or in
     any way transfer any voting  rights  pertaining  to the  Collateral  to any
     person or entity. -----------------------------------

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
interests  or  shares  of any  class  of  securities  of such  issuer,  (ii) any
instrument  convertible  voluntarily by the holder thereof or automatically upon
the occurrence or non-occurrence of any event or condition into, or exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding the Interests  unless  consented to in writing by Secured
Party.

                                                     ARTICLE V
                                          DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees  that it shall  (i)  promptly  advise  Secured  Party in  writing  of any
litigation  filed against Debtor and of any condition,  event or act which comes
to its attention that would or might have a material  adverse effect on Debtor's
financial  condition  or on Debtor's  ability to perform the  Obligations,  (ii)
except  as  expressly   contemplated  in  Section  4.3(e)(i)  and  (ii)  of  the
Contribution  Agreement,  pay all available funds toward  repayment of the Note,
regardless  of whether  payment of such amounts  exceeds the  required  payments
under  the Note and  (iii) if  Borrower  uses any  proceeds  from the  Note,  to
acquire,  directly or indirectly,  a one hundred  percent  (100%)  interest in a
Target Center (as defined in the Contribution  Agreement),  Borrower shall cause
such  Target  Center to execute a  security  agreement,  acceptable  in form and
substance  to Lender,  granting  to Lender or one of Lender's  subsidiaries  the
highest available priority security interest in all of the assets of such Target
Center.

                                                    ARTICLE VI
                                                NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

         6.1 Liens. Grant, suffer, or permit liens on, or security interests in,
the Collateral.

          6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with any
     covenants or agreements  regarding  other debt which will or would with the
     passage of time or upon demand  cause the  maturity of any other debt to be
     accelerated. -----------------------

                                                    ARTICLE VII
                                               DEFAULT AND REMEDIES

          7.1 Events of Default.  An Event of Default  (herein so called)  shall
     exist  if  any  one  or  more  of  the   following   events   shall  occur:
     -----------------

          (a) The failure of Debtor to pay any amount  required to be paid under
     the Loan Agreement (including, without limitation,  principal, interest and
     fees due thereunder), or any other amount which Debtor may now or hereafter
     owe to Secured  Party under any Other  Agreement or  otherwise,  within ten
     (10) calendar days after such amount is due;

          (b) The failure of Debtor to pay any  Obligation  after such amount is
     due  (and,  if  applicable  under the  terms of any  contractual  agreement
     creating or governing  such  Obligation,  after the  expiration of any cure
     period expressly required);

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement;

          (d) Any representation or warranty made by Debtor in this Agreement or
     any Other  Agreement  between  Debtor and  Secured  Party shall be false or
     materially  misleading,  as  determined  in the  reasonable  discretion  of
     Secured Party;

          (e) Any  event of  default  shall  occur  under  the terms of the Loan
     Agreement  and shall not be cured  within the time  expressly  provided for
     with respect thereto in the Loan Agreement;

                  (f) If Debtor or any other party  obligated to pay any portion
of the  Obligations:  (i)  becomes  insolvent,  or makes a transfer  in fraud of
creditors,  or makes an assignment  for the benefit of  creditors,  or admits in
writing its inability to pay its debts as they become due; (ii) generally is not
paying its debts as such debts  become due and  Secured  Party,  in good  faith,
determines that such event or condition  could lead to a material  impairment of
the Collateral, or any part thereof, or of any other payment security for any of
the Obligations;  (iii) has a receiver,  trustee or custodian  appointed for, or
take possession of, all or substantially  all of the assets of such party or any
of the  Collateral,  either  in a  proceeding  brought  by  such  party  or in a
proceeding  brought against such party and such appointment is not discharged or
such  possession  is not  terminated  within sixty (60) days after the effective
date thereof or such party  consents to or  acquiesces  in such  appointment  or
possession;  (iv) files a petition for relief under the United States Bankruptcy
Code or any other present or future federal or state  insolvency,  bankruptcy or
similar laws (all of the foregoing  hereinafter  collectively called "Applicable
Bankruptcy  Law") or an  involuntary  petition for relief is filed  against such
party under any Applicable  Bankruptcy Law and such involuntary  petition is not
dismissed  within  sixty  (60) days after the  filing  thereof,  or an order for
relief naming such party is entered under any Applicable  Bankruptcy Law, or any
composition, rearrangement, extension, reorganization or other relief of debtors
now or hereafter  existing is requested or consented to by such party; (v) fails
to  have  discharged  within  a  period  of  sixty  (60)  days  any  attachment,
sequestration  or similar writ levied upon,  or any claim  against or affecting,
any  property  of such party;  or (vi) fails to pay within  ninety (90) days any
final money judgment against such party; or

          (g) The  issuer  of any  securities  constituting  Collateral  files a
     petition for relief under any  Applicable  Bankruptcy  Law, an  involuntary
     petition for relief is filed  against any such issuer under any  Applicable
     Bankruptcy Law and such involuntary petition is not dismissed within thirty
     (30) days after the filing thereof,  or an order for relief naming any such
     issuer is entered under any Applicable Bankruptcy Law.

          7.2  Secured  Party's  Remedies.  Upon the  occurrence  of an Event of
     Default:

          (a)  Secured  Party  may  declare  the  Obligations  in  whole or part
     immediately  due and may enforce  payment and  performance  of the same and
     exercise  any rights  under the Texas UCC,  rights and  remedies of Secured
     Party under this Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (c) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (d) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in any type of offering  which  complies  with, or is exempt from the
registration  requirements  of, the  Securities  Act of 1933 and any  applicable
state  securities laws, and no sale so made in good faith by Secured Party shall
be deemed to be not "commercially reasonable" because so made.

          (e) Not in  limitation  of any  other  provision  of  this  Agreement,
     Secured  Party shall have all rights and remedies of a secured  party under
     the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the  Contribution  Agreement or any
Other  Agreement;  (d)  then,  to or among the  amounts  of fees,  interest  and
principal then owing and unpaid in respect of the Obligations,  in such priority
as Secured Party may determine in its discretion;  and (e) the remainder of such
proceeds,  if  any,  shall  be  paid  to  Debtor.  If  such  proceeds  shall  be
insufficient to discharge the entire  Obligations,  Secured Party shall have any
other available legal recourse  against Debtor under, or for the performance of,
the  Contribution  Agreement and any Other Agreement  between Debtor and Secured
Party,  for the deficiency,  together with interest  thereon at the maximum rate
permitted under applicable law.

          7.4  Enforcement of  Obligations.  Nothing in this Agreement or in any
     other document or agreement  shall affect or impair the  unconditional  and
     absolute right of Secured Party to enforce the  Obligations as and when the
     same shall become due in accordance with the terms of any Other  Agreement.
     --------------------------

                                                   ARTICLE VIII
                                              RIGHTS OF SECURED PARTY

          8.1 Subrogation.  Upon the occurrence of an Event of Default,  Secured
     Party,  at its election,  may subrogate to all of the interest,  rights and
     remedies of the Debtor,  in respect to any of the  Collateral or agreements
     pertaining thereto. -----------

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

          8.3  Performance  by Secured  Party.  If Debtor  fails to perform  any
     agreement contained herein,  Secured Party may itself perform, or cause the
     performance  of, such  agreement,  and the  reasonable  expenses of Secured
     Party  incurred in  connection  therewith  shall be payable by Debtor under
     Section 8.8. In no event, however,  shall Secured Party have any obligation
     or duties  whatsoever  to  perform  any  covenant  or  agreement  of Debtor
     contained  herein,  and any such  performance  by  Secured  Party  shall be
     ---------------------------- wholly discretionary with Secured Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY, PROTECT, DEFEND AND HOLD HARMLESS SECURED PARTY AND ITS
SUBSIDIARIES,  AND EACH OF THEIR OFFICERS, DIRECTORS,  REPRESENTATIVES,  AGENTS,
EMPLOYEES,  LENDERS,  SUCCESSORS AND ASSIGNS,  FROM AND AGAINST ALL LIABILITIES,
CLAIMS, DAMAGES,  LOSSES, FINES, PENALTIES,  CAUSES OF ACTIONS, SUITS, JUDGMENTS
AND EXPENSES (INCLUDING COURT COSTS,  ATTORNEY'S FEES AND COST OF INVESTIGATION)
OF ANY  NATURE,  KIND OR  DESCRIPTION  OF ANY  PERSON  OR  ENTITY,  DIRECTLY  OR
INDIRECTLY,  ARISING OUT OF, CAUSED BY OR RESULTING  FROM (IN WHOLE OR IN PART),
ANY ACT OR  OMISSION  OF SECURED  PARTY,  OR ANYONE  ACTING ON BEHALF OF SECURED
PARTY,  IN CONNECTION  WITH THE  COLLATERAL,  INCLUDING  WITHOUT  LIMITATION ANY
MARKET FLUCTUATIONS IN THE COLLATERAL AS A RESULT OF SECURED PARTY'S SALE OF, OR
FAILURE TO SELL, THE INTERESTS AT ANY  PARTICULAR  TIME WHEN IT HAS THE RIGHT TO
DO  SO.  THE  FOREGOING  INDEMNITY  SHALL  SURVIVE  THE  EXPIRATION  OR  EARLIER
TERMINATION OF THIS AGREEMENT.

          8.6  Right of  Secured  Party to  Defend  Action  Affecting  Security.
     Secured  Party may,  at the  expense  of  Debtor,  appear in and defend any
     action or  proceeding  at law or in  equity  purporting  to affect  Secured
     Party's       Security       Interest      under      this       Agreement.
     ----------------------------------------------------------

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed and observed by Debtor under any Other Agreement,  or in respect
of the Collateral (subject to any applicable default cure period), Secured Party
(a) may but  shall not be  obligated  to take any  action  Secured  Party  deems
necessary  or  desirable  to  prevent  or remedy  any such  default by Debtor or
otherwise to protect the Security Interest,  and (b) shall have the absolute and
immediate right to take possession of the Collateral or any part thereof (to the
extent Secured Party has not previously taken  possession) to such extent and as
often as the Secured Party, in its sole discretion, deems necessary or desirable
in order to prevent  or to cure any such  default by  Debtor,  or  otherwise  to
protect the security of this Agreement. Secured Party may advance or expend such
sums of money for the account of Debtor as Secured Party in its sole  discretion
deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become  involved  by reason of or  arising  out of any  Other  Agreement  or the
Collateral,  shall be a part of the  Obligations  and shall be paid by Debtor to
Secured  Party,  upon demand,  and shall bear interest until paid at the maximum
rate of interest  permitted by applicable law, from the date incurred by Secured
Party until repaid by Debtor.

          8.9. Convertible Collateral.  Secured Party may present for conversion
     any Collateral which is convertible into any other instrument or investment
     security or a  combination  thereof with cash,  but Secured Party shall not
     have any duty to present for conversion any Collateral unless it shall have
     received from Debtor detailed written instructions to that effect at a time
     reasonably  far in  advance  of the  final  conversion  date to  make  such
     conversion possible. ----------------------

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

          8.11 Remedies.  No right or remedy herein reserved to Secured Party is
     intended to be exclusive  of any other right or remedy,  but each and every
     such  remedy  shall be  cumulative,  not in lieu of, but in addition to any
     other rights or remedies  given under this Agreement and all other security
     documents.  Any and all of  Secured  Party's  rights  and  remedies  may be
     exercised  from  time to time  and as  often  as such  exercise  as  deemed
     necessary or desirable by Secured Party. --------

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

                                                    ARTICLE IX
                                                   MISCELLANEOUS

          9.1 Terms Commercially  Reasonable.  The terms of this Agreement shall
     be deemed  commercially  reasonable  within  the  meaning of the Texas UCC.
     -----------------------------

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:       1301 Capital of Texas Hwy., Suite C-300
                                       Austin, Travis County, Texas 78746
                                       Attn: President

                  with copy to:        Timothy L. LaFrey, Esq.
                                       Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                       1900 Frost Bank Plaza
                                       816 Congress Avenue
                                       Austin, Texas 78701

                  Debtor:              Prime/BDR Acquisition, L.L.C.

                                       1301 Capital of Texas Hwy., Suite C-300
                                       Austin, Travis County, Texas 78746
                                       Attn: President

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

          9.4 Waiver. No delay of Secured Party in exercising any power or right
     shall operate as a waiver thereof; nor shall any single or partial exercise
     of any power or right  preclude  other or further  exercise  thereof or the
     exercise  of any other  power or right.  No waiver by Secured  Party of any
     right  hereunder  of any default by Debtor  shall be binding  upon  Secured
     Party  unless in writing,  and no failure by Secured  Party to exercise any
     power or right  hereunder  or waiver of any default by Debtor  ------ shall
     operate as a waiver of any other or further exercise of such right or power
     of any further default.

          9.5 Agreement Continuing. This Agreement shall constitute a continuing
     agreement, applying to all future as well as existing transactions, whether
     or not of the character contemplated at the date of this Agreement,  and if
     all  transactions  between  Secured Party and Debtor shall be closed at any
     time,  shall be  equally  applicable  to any new  transactions  thereafter.
     Provisions of this Agreement,  unless by their terms exclusive, shall be in
     addition to those contained in any Other Agreement. --------------------

          9.6 Definitions.  Unless the context indicated otherwise,  definitions
     in the Texas  Business and Commerce  Code ("Texas  UCC") apply to words and
     phrases in this  Agreement;  if Texas UCC definitions  conflict,  Chapter 9
     definitions apply. -----------

          9.7  Miscellaneous.   In  this  Agreement,  whenever  the  context  so
     requires,  the neuter gender  includes the masculine and feminine,  and the
     singular  number  includes  the  plural and vice  versa.  The  headings  of
     paragraphs  herein are inserted  only for  convenience  and shall in no way
     define,  describe  or limit the scope of intent of any  provisions  of this
     Agreement. No change, amendment,  modification,  cancellation, or discharge
     of any provision of this  Agreement  shall be valid unless  consented to in
     ------------- writing by Secured Party.

          9.8 Assignment of Secured Party's  Interest.  Secured Party shall have
     the right to assign  all or any  portion  of its  rights in this  Agreement
     without  approval or consent.  Debtor  acknowledges  that Lender intends to
     make a collateral  assignment  of its rights under this  Agreement  for the
     benefit of one or more of its lenders. Debtor may not assign this Agreement
     or any of its rights or  obligations  hereunder  without the express  prior
     written     consent     of    Secured     Party    in    each     instance.
     --------------------------------------

          9.9 Applicable Laws. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED
     IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE APPLICABLE  LAWS
     OF THE UNITED STATES OF AMERICA. ---------------

          9.10 ENTIRE AGREEMENT.  THIS AGREEMENT,  THE LOAN AGREEMENT,  THE NOTE
     AND THE CONTRIBUTION  AGREEMENT  REPRESENT THE FINAL AGREEMENT  BETWEEN THE
     PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS,
     OR SUBSEQUENT ORAL  AGREEMENTS OF THE PARTIES.  THERE ARE NO UNWRITTEN ORAL
     AGREEMENTS BETWEEN THE PARTIES. ----------------

                                             [Signature page follows]



                                                       2
<PAGE>


                                                 SIGNATURE PAGE TO
                                                  ASSIGNMENT AND
                                                SECURITY AGREEMENT


         EXECUTED this ____ day of September, 1999.


DEBTOR:                             Prime/BDR Acquisition, L.L.C.

                                    By: ______________________________________

                                    Printed Name: _____________________________

                                    Title: _____________________________________

SECURED PARTY:                      Prime Medical Operating, Inc.

                                    By: ______________________________________

                                    Printed Name: _____________________________

                                    Title: _____________________________________


<PAGE>


                                   EXHIBIT G5

                                     FORM OF

                                 PROMISSORY NOTE

                        Austin, Texas ____________, 1999

PROMISE TO PAY: For value  received,  the undersigned  Borrower  (whether one or
more) promises to pay to the order of Lender the Principal Amount, together with
interest on the unpaid  balance of such  amount,  in lawful  money of the United
States of America, in accordance with all the terms,  conditions,  and covenants
of this Note and the Loan Documents identified below.

BORROWER:    Prime/BDR Acquisition, L.L.C., a Delaware limited liability company

BORROWER'S ADDRESS FOR NOTICE:        1301 Capital of Texas Highway, Suite C-300
                                      Austin, Texas  78746
                                      Attention: President

LENDER:  Prime Medical Operating, Inc., a Delaware corporation

LENDER'S ADDRESS FOR PAYMENT:        1301 Capital of Texas Highway, Suite C-300,
                                     Austin, Texas 78746
                                     Attention: Chief Financial Officer

PRINCIPAL AMOUNT:  ______________________ ($____________)

INTEREST RATE:  Fifteen Percent (15%)

PAYMENT  TERMS:  Interest on the unpaid  balance of this Note is due and payable
quarterly,   beginning  ______________,   1999,  and  continuing  regularly  and
quarterly  thereafter on or before the first day of ____________,  ____________,
____________  and  ____________  of each year,  until  [seven years from date of
loan] (the "Maturity  Date"),  when the  outstanding  principal  balance and all
accrued  interest shall be due and payable in full.  Interest will be calculated
on the unpaid  principal  balance.  Each payment  will be credited  first to the
accrued interest and then to the reduction of principal.

LOAN AGREEMENT:  This Note is executed  pursuant to and is governed by the terms
of that certain Loan Agreement dated  September ___, 1999,  executed by Borrower
and Lender, as amended (collectively, the "Loan Agreement").

1.       INTEREST PROVISIONS:

(a)      Rate:  The principal  balance of this Note from time to time  remaining
         unpaid prior to maturity  shall bear  interest at the Interest Rate per
         annum stated above.

(b)      Maximum  Lawful  Interest:  The term  "Maximum  Lawful  Rate" means the
         maximum rate of interest and the term "Maximum Lawful Amount" means the
         maximum amount of interest that is permissible  under  applicable state
         or  federal  law for the type of loan  evidenced  by this  Note and the
         other Loan  Documents.  If the  Maximum  Lawful  Rate is  increased  by
         statute or other  governmental  action  subsequent  to the date of this
         Note, then the new Maximum Lawful Rate shall be applicable to this Note
         from  the  effective  date  thereof,  unless  otherwise  prohibited  by
         applicable law.

     (c)  Spreading  of  Interest:  Because  of  the  possibility  of  irregular
          periodic  balances  of  principal  or  premature  payment,  the  total
          interest  that will  accrue  under this Note cannot be  determined  in
          advance.  Lender does not intend to contract for,  charge,  or receive
          more than the Maximum Lawful Rate or Maximum  Lawful Amount  permitted
          by applicable  state or federal law, and to prevent such an occurrence
          Lender and  Borrower  agree that all  amounts  of  interest,  whenever
          contracted for,  charged,  or received by Lender,  with respect to the
          loan of money evidenced by this Note,  shall be spread,  prorated,  or
          allocated over the full period of time this Note is unpaid,  including
          the period of any  renewal or  extension  of this Note.  If demand for
          payment of this Note is made by Lender  prior to the full stated term,
          the total amount of interest  contracted for, charged,  or received to
          the time of such demand shall be spread,  prorated, or allocated along
          with any  interest  thereafter  accruing  over the full period of time
          that  this  Note   thereafter   remains  unpaid  for  the  purpose  of
          determining if such interest exceeds the Maximum Lawful Amount.

     (d)  Excess Interest: At maturity (whether by acceleration or otherwise) or
          on earlier final payment of this Note,  Lender shall compute the total
          amount of interest that has been contracted for, charged,  or received
          by Lender or payable by  Borrower  under  this Note and  compare  such
          amount to the Maximum  Lawful  Amount that could have been  contracted
          for, charged, or received by Lender. If such computation reflects that
          the total amount of interest that has been contracted for, charged, or
          received by Lender or payable by Borrower  exceeds the Maximum  Lawful
          Amount,  then Lender  shall apply such excess to the  reduction of the
          principal  balance  and not to the  payment  of  interest;  or if such
          excess  interest  exceeds the unpaid  principal  balance,  such excess
          shall be refunded to Borrower. This provision concerning the crediting
          or refund of excess  interest shall control and take  precedence  over
          all other  agreements  between  Borrower  and  Lender so that under no
          circumstances  shall the total interest  contracted for,  charged,  or
          received by Lender exceed the Maximum Lawful Amount.

     (e)  Interest  After  Default:  At Lender's  option,  the unpaid  principal
          balance shall bear interest after maturity (whether by acceleration or
          otherwise) at the "Default  Interest Rate." The Default  Interest Rate
          shall be, at Lender's  option,  (i) the Maximum  Lawful Rate,  if such
          Maximum  Lawful Rate is  established  by  applicable  law; or (ii) the
          Interest  Rate  stated  on the  first  page of this Note plus five (5)
          percentage  points,  if no  Maximum  Lawful  Rate  is  established  by
          applicable  law; or (iii)  eighteen  percent (18%) per annum;  or (iv)
          such  lesser rate of  interest  as Lender in its sole  discretion  may
          choose to charge;  but never more than the Maximum Lawful Rate or at a
          rate that would cause the total interest  contracted for, charged,  or
          received by Lender to exceed the Maximum Lawful Amount.

(f)      Daily  Computation of Interest:  To the extent  permitted by applicable
         law,  Lender at its option will calculate the per diem interest rate or
         amount  based on the actual  number of days in the year (365 or 366, as
         the case may be), and charge that per diem interest rate or amount each
         day. In no event  shall  Lender  compute the  interest in a manner that
         would cause Lender to contract for,  charge,  or receive  interest that
         would exceed the Maximum Lawful Rate or the Maximum Lawful Amount

2.       DEFAULT PROVISIONS:

(a)      EVENTS OF DEFAULT AND  ACCELERATION  OF  MATURITY:  LENDER  MAY,  AFTER
         THIRTY (30) DAYS' WRITTEN NOTICE TO BORROWER AND BORROWER'S  FAILURE TO
         CURE WITHIN SUCH 30-DAY  PERIOD AND WITHOUT  FURTHER  NOTICE OR DEMAND,
         (except as otherwise  required by statute),  ACCELERATE THE MATURITY OF
         THIS NOTE AND  DECLARE  THE ENTIRE  UNPAID  PRINCIPAL  BALANCE  AND ALL
         ACCRUED INTEREST AT ONCE DUE AND PAYABLE IF:

               (i)  There  is  default  in the  payment  of any  installment  of
          principal,  interest,  or any other sum  required to be paid under the
          terms of this Note or any of the Loan Documents; or

               (ii) There is a breach or default  (other than by Lender or Prime
          Medical Services,  Inc.) under this Note or any of the Loan Documents,
          including any instrument securing the payment of this Note or any loan
          agreement relating to the advance of loan proceeds.

     (b)  WAIVER BY BORROWER: EXCEPT AS PROVIDED IN PARAGRAPH 2(a) HEREOF AND IN
          ANY OTHER LOAN  DOCUMENT,  BORROWER AND ALL OTHER  PARTIES  LIABLE FOR
          THIS NOTE WAIVE, DEMAND,  NOTICE OF INTENT TO DEMAND,  PRESENTMENT FOR
          PAYMENT,  NOTICE OF  NONPAYMENT,  PROTEST,  NOTICE OF PROTEST,  GRACE,
          NOTICE OF DISHONOR, NOTICE OF INTENT TO ACCELERATE MATURITY, NOTICE OF
          ACCELERATION  OF MATURITY,  AND DILIGENCE IN  COLLECTION.  EACH MAKER,
          SURETY,  ENDORSER, AND GUARANTOR OF THIS NOTE WAIVES AND AGREES TO ONE
          OR MORE  EXTENSIONS FOR ANY PERIOD OR PERIODS OF TIME, AND ANY PARTIAL
          PAYMENTS, BEFORE OR AFTER MATURITY, WITHOUT PREJUDICE TO THE HOLDER OF
          THIS NOTE. EACH MAKER, SURETY,  ENDORSER,  AND GUARANTOR WAIVES NOTICE
          OF ANY AND ALL RENEWALS, EXTENSIONS, REARRANGEMENTS, AND MODIFICATIONS
          OF THIS NOTE.

(c)      Non-Waiver  by Lender:  Any previous  extension  of time,  forbearance,
         failure  to  pursue  some  remedy,  acceptance  of  late  payments,  or
         acceptance of partial payment by Lender, before or after maturity, does
         not constitute a waiver by Lender of its  subsequent  right to strictly
         enforce the collection of this Note according to its terms.

     (d)  Other  Remedies  Not  Required:  Lender shall not be required to first
          file suit,  exhaust all  remedies,  or enforce its rights  against any
          security in order to enforce payment of this Note.

(e)      Joint and Several Liability: Each Borrower who signs this Note, and all
         of the other  parties  liable for the  payment  of this  Note,  such as
         guarantors,  endorsers,  and sureties, are jointly and severally liable
         for the payment of this Note.

(f)      Attorney's  Fees:  If Lender  requires  the  services of an attorney to
         enforce the payment of this Note or the  performance  of the other Loan
         Documents,  or if this Note is collected through any lawsuit,  probate,
         bankruptcy, or other judicial proceeding, Borrower agrees to pay Lender
         an amount equal to its reasonable  attorney's fees and other collection
         costs.  This  provision  shall be limited by any  applicable  statutory
         restrictions relating to the collection of attorney's fees.

3.       MISCELLANEOUS PROVISIONS:

(a)  Subsequent  Holder:  All references to Lender in this Note shall also refer
     to any  subsequent  owner or holder of this Note by  transfer,  assignment,
     endorsement, or otherwise.

(b)      Transfer:  Borrower  acknowledges  and agrees that Lender may  transfer
         this Note or partial  interests in the Note to one or more  transferees
         or participants, including without limitation transfers provided for in
         Section  8.10 of the Loan  Agreement.  Borrower  authorizes  Lender  to
         disseminate  to any  such  transferee  or  participant  or  prospective
         transferee or participant any information it has pertaining to the loan
         evidenced  by  this  Note,   including,   without  limitation,   credit
         information  on Borrower and any  guarantor of this Note and any of the
         type of information described in Section 8.10 of the Loan Agreement.

(c)      Other Parties Liable: All promises, waivers, agreements, and conditions
         applicable to Borrower shall likewise be applicable to and binding upon
         any other parties  primarily or  secondarily  liable for the payment of
         this Note, including all guarantors, endorsers, and sureties.

(d)      Successors  and Assigns:  The  provisions of this Note shall be binding
         upon and for the benefit of the successors,  assigns, heirs, executors,
         and administrators of Lender and Borrower.

(e)      No Duty or Special Relationship:  Borrower acknowledges that Lender has
         no duty of good faith to Borrower,  and Borrower  acknowledges  that no
         fiduciary,  trust, or other special  relationship exists between Lender
         and Borrower.

(f)      Modifications:  Any  modifications  agreed to by Lender relating to the
         release of  liability of any of the parties  primarily  or  secondarily
         liable for the  payment  of this  Note,  or  relating  to the  release,
         substitution,  or subordination of all or part of the security for this
         Note, shall in no way constitute a release of liability with respect to
         the other parties or security not covered by such modification.

(g)      Entire  Agreement:  Borrower  warrants  and  represents  that  the Loan
         Documents  constitute the entire agreement  between Borrower and Lender
         with  respect to the loan  evidenced  by this Note and  agrees  that no
         modification,  amendment,  or additional agreement with respect to such
         loan  or  the  advancement  of  funds  thereunder  will  be  valid  and
         enforceable unless made in writing signed by both Borrower and Lender.

(h)      Borrower's  Address  for  Notice:  All  notices  required to be sent by
         Lender to Borrower  shall be sent by U.S.  Mail,  postage  prepaid,  to
         Borrower's  Address  for Notice  stated on the first page of this Note,
         until Lender shall receive written  notification from Borrower of a new
         address for notice.

(i)      Lender's  Address for  Payment:  All sums payable by Borrower to Lender
         shall be paid at Lender's  Address for Payment stated on the first page
         of this Note, or at such other address as Lender shall  designate  from
         time to time.

(j)  Business Use:  Borrower warrants and represents to Lender that the proceeds
     of this Note will be used solely for business or commercial  purposes,  and
     in no way will the  proceeds be used for  personal,  family,  or  household
     purposes.

(k)      Chapter 15 Not  Applicable:  It is  understood  that  Chapter 15 of the
         Texas Credit Code  relating to certain  revolving  credit loan accounts
         and tri-party accounts is not applicable to this Note.

(l)      APPLICABLE  LAW: THIS NOTE HAS BEEN EXECUTED AND DELIVERED IN TEXAS AND
         SHALL BE CONSTRUED IN ACCORDANCE  WITH THE APPLICABLE LAWS OF THE STATE
         OF TEXAS AND THE LAWS OF THE  UNITED  STATES OF AMERICA  APPLICABLE  TO
         TRANSACTIONS IN TEXAS.

4.       LOAN DOCUMENTS:

(a)      This Note.

(b)      The Loan Agreement and the Loan Documents as defined therein.

(c)      All other documents signed in connection with the Loan Agreement or the
         loan  evidenced  by this  Note,  including,  without  limitation,  that
         certain  Contribution  Agreement,  dated  effective  September 1, 1999,
         between and among Borrower,  Lender,  Prime Medical  Services,  Inc., a
         Delaware  corporation,   Prime/BDEC  Acquisition,  L.L.C.,  a  Delaware
         limited  liability  company,  Barnet Dulaney Eye Center,  P.L.L.C.,  an
         Arizona  professional  limited  liability  company,   LASIK  Investors,
         L.L.C., a Delaware limited liability company,  David D. Dulaney,  M.D.,
         Ronald  W.  Barnet,   M.D.,  and  Mark  Rosenberg  (the   "Contribution
         Agreement") and each  Transaction  Document (as such term is defined in
         the Contribution Agreement).

                            [Signature page follows]


<PAGE>


S-1



                                EXECUTION PAGE TO

                                 PROMISSORY NOTE

EXECUTED this ___ day of ___________, 1999.



           BORROWER:

                    Prime/BDR Acquisition, L.L.C., a Delaware limited liability
                       company



                                    By: ________________________________________

                          Printed Name: ________________________________________

                                 Title: ________________________________________

<PAGE>
                                   EXHIBIT-H




                               MEMBERSHIP INTEREST

                         TRANSFER RESTRICTION AGREEMENT

     This Membership Interest Transfer Restriction  Agreement (this "Agreement")
is entered into  effective as of the 1st day of  September,  1999,  by and among
LASIK Investors,  L.L.C., a Delaware limited  liability company (the "Company"),
Prime  Medical  Operating,  Inc., a Delaware  corporation  ("Prime"),  Ronald W.
Barnet, M.D.  ("Barnet"),  David D. Dulaney,  M.D.  ("Dulaney"),  Mark Rosenberg
("Rosenberg"),  Scott A. Perkins, M.D. ("Perkins"),  and Robert B. Pinkert, O.D.
("Pinkert").  Barnet, Dulaney, Rosenberg, Perkins and Pinkert, together with any
subsequent  Members in the Company who  hereafter  execute this  Agreement,  are
collectively referred to herein as the "Members".

                                R E C I T A L S:

             WHEREAS,  Barnet, Dulaney,  Rosenberg,  Perkins and Pinkert own all
the  issued  and  outstanding  membership  interests  of the  Company  (all such
membership  interests,  together with any hereafter  acquired,  are  hereinafter
referred to as the "Membership Interests"); and

             WHEREAS, this Agreement is a "Transaction  Document," as defined in
that  certain  Contribution  Agreement  (the  "Contribution   Agreement")  dated
effective September 1, 1999, by and among Prime, Prime Medical Services, Inc., a
Delaware corporation ("PMSI"), the Company, Barnet Dulaney Eye Center, P.L.L.C.,
an  Arizona  professional  limited  liability  company,  Prime/BDR  Acquisition,
L.L.C., a Delaware limited liability company, Prime/BDEC Acquisition,  L.L.C., a
Delaware limited liability company, Barnet, Dulaney and Rosenberg.

             WHEREAS,  the  Members,  the Company and Prime desire to enter into
this Agreement to control the distribution of ownership interests in the Company
and to promote the harmonious management of the Company's affairs.

             NOW,  THEREFORE,  in  consideration  of the  foregoing,  the mutual
covenants and agreements contained herein, and for other valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

                                    ARTICLE I

               PERMITTED TRANSFERS; RESTRICTIONS AGAINST TRANSFER

As used in this Agreement,  "Permitted Transfers" shall mean any transfer of all
or any  part of any  Member's  Membership  Interest  to (i) the  members  of the
immediate  family of the Member or a trust or trusts for the  benefit of members
of the immediate family of the Member, provided that after any such transfer the
Member  retains  the sole  express  right to vote,  or direct  the votes of, the
Membership  Interest,  (ii) any other  Member,  provided that after any transfer
pursuant to this subsection  (ii) is consummated,  Barnet and Dulaney (or trusts
that hold Membership Interests as a result of Permitted Transfers subsection (i)
above) must  collectively own in the aggregate at least fifty-one  percent (51%)
of the total outstanding  Membership  Interests of the Company,  or (iii) Prime.
Any Member  transferring all or a portion of its Membership Interest pursuant to
a  Permitted  Transfer  shall  give  written  notice of the  Permitted  Transfer
(containing the same  information as required for notice under Section 2.1.1) to
Prime and the other Members fifteen (15) days prior to the effective date of the
Permitted Transfer. Except for a Permitted Transfer, or as otherwise provided in
this Agreement, a Member shall not transfer, assign, pledge,  hypothecate, or in
any way alienate any  Membership  Interest,  or any  interest  therein,  whether
voluntarily  or by operation of law, or by gift or otherwise,  without the prior
written consent of the Company,  the other Members and Prime,  which consent may
be withheld in their sole and absolute  discretion.  Any  purported  transfer in
violation of any  provision  of this  Agreement  shall be void and  ineffectual,
shall not operate to transfer any interest or title to the purported transferee,
and shall give the Company, the other Members and Prime options to purchase such
Membership Interest in the manner and on the conditions hereinafter provided. As
used in this Agreement,  "Option  Members" shall mean all Members of the Company
except  (i) the Member  who,  prior to the  proposed  transfer  or the  incident
resulting in the proposed transfer of all or a portion of a Membership Interest,
owned such interest and (ii) Rosenberg.

                                   ARTICLE II

                                     OPTIONS

2.1          OPTION UPON VOLUNTARY TRANSFER.

             2.1.1  Notice of  Intention  to  Transfer.  If a Member  intends to
voluntarily  transfer any of its Membership  Interest,  other than pursuant to a
Permitted  Transfer,  to any person other than the Company,  and does not obtain
the written consents required in ARTICLE I hereof, the Member shall give written
notice to the other  Members,  Rosenberg  and Prime stating (i) the intention to
transfer a Membership  Interest,  (ii) the amount of  Membership  Interest to be
transferred,  (iii) the name,  business  and  residence  address of the proposed
transferee,  (iv) the nature and amount of the consideration,  and (v) the other
terms of the proposed sale.

             2.1.2 Option to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days after  receipt of the notice of intent to transfer,  an
option  to  purchase  all  or  any  portion  of  the  Membership   Interest  the
transferring Member intends to transfer,  for the price and upon the other terms
stated in the notice of intent to transfer.  If the Option Members fail,  within
such 30-day period,  to exercise  their purchase  option (by delivery of written
notice) with respect to the entire Membership  Interest being  transferred,  the
Option  Members shall be deemed to have elected not to exercise  their  purchase
option with respect to such unpurchased Membership Interest.  Upon any notice of
non-exercise (or deemed  non-exercise) by the Option Members,  Rosenberg (if not
the transferring  Member) shall have, and may exercise within 30 days of receipt
of notice of such non-exercise (or deemed  non-exercise),  an option to purchase
all or any portion of such unpurchased  Membership  Interest upon the same terms
and conditions.  If Rosenberg fails,  within such 30-day period, to exercise his
purchase  option (by  delivery  of written  notice)  with  respect to the entire
unpurchased  Membership Interest,  Rosenberg shall be deemed to have elected not
to  exercise  his  purchase  option  with  respect to any  remaining  Membership
Interest. Upon any notice of non-exercise (or deemed non-exercise) by Rosenberg,
Prime shall have,  and may exercise  within 30 days of receipt of notice of such
non-exercise  (or  deemed  non-exercise),  an  option  to  purchase  all of such
remaining Membership Interest upon the same terms and conditions.

             2.1.3 Death Before Closing.  If a Member who proposed to transfer a
Membership  Interest  dies  prior  to the  closing  of  the  sale  and  purchase
contemplated  by this  Section  2.1, the  Membership  Interest of such  deceased
Member shall be the subject of sale and purchase under Section 2.3.

             2.1.4 Allowable  Consideration.  All parties hereto acknowledge and
agree that it would be  impractical  to exercise  an option to purchase  arising
pursuant to this Section 2.1 whenever the proposed  consideration to be received
by the transferring  Member is other than cash or cash  equivalents.  Therefore,
the parties agree that no transfer  shall be permitted and no option shall arise
pursuant to this Section 2.1 whenever the  consideration to be received from the
proposed transferee is other than cash or cash equivalents.

2.2          OPTION UPON CERTAIN INVOLUNTARY TRANSFERS.

             2 2.1  Exercise  Event and  Notice.  The filing of a  voluntary  or
involuntary petition of bankruptcy by or on behalf of a Member, an assignment by
a Member of any of its Membership Interest, or of any right or interest therein,
for the benefit of creditors, or the voluntary transfer,  transfer by law or any
other transfer,  of any Membership Interest, or of any right or interest therein
(other  than  transfers  governed by ARTICLE I or  Sections  2.1,  2.3 or 2.4 or
ARTICLE  VII  hereof),  shall give the other  Members,  Rosenberg  and Prime the
option to  purchase  the  Membership  Interest of such  bankrupt  Member or such
transferred  Membership  Interest  as  provided  herein.  Upon the  filing  of a
voluntary or  involuntary  petition of bankruptcy by or on behalf of a Member or
an assignment by Member of any of its  Membership  Interest,  or of any right or
interest  therein,  for the  benefit of  creditors,  the Member or its  personal
representative  shall  promptly  give written  notice of such  occurrence to the
other  Members,  Rosenberg  and Prime.  In the event of a transfer of Membership
Interest,  as described above, the Member  transferring such Membership Interest
shall  promptly  give  written  notice of such  transfer  to the other  Members,
Rosenberg and Prime.

             2.2.2 Option to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days after receipt of the notice of the applicable  exercise
event,  an option to purchase all or any portion of the Membership  Interest the
bankrupt or transferring Member intends to transfer,  for the price and upon the
other terms hereinafter provided. If the Option Members fail, within such 30-day
period,  to exercise their purchase  option (by delivery of written notice) with
respect to the entire Membership Interest being transferred,  the Option Members
shall be deemed to have  elected  not to  exercise  their  purchase  option with
respect to such unpurchased Membership Interest. Upon any notice of non-exercise
(or deemed  non-exercise) by the Option Members,  Rosenberg (if not the bankrupt
or  transferring  Member) shall have, and may exercise within 30 days of receipt
of notice of such non-exercise (or deemed  non-exercise),  an option to purchase
all or any portion of such  unpurchased  Membership  Interest  for the price and
upon the other terms  hereinafter  provided.  If  Rosenberg  fails,  within such
30-day period,  to exercise his purchase  option (by delivery of written notice)
with respect to the entire unpurchased  Membership Interest,  Rosenberg shall be
deemed to have elected not to exercise  his purchase  option with respect to any
remaining  Membership  Interest.  Upon any  notice of  non-exercise  (or  deemed
non-exercise) by Rosenberg, Prime shall have, and may exercise within 30 days of
receipt of notice of such  non-exercise (or deemed  non-exercise),  an option to
purchase all of such  remaining  Membership  Interest for the price and upon the
other terms hereinafter provided.

2.3          PURCHASE AND SALE OF MEMBERSHIP INTEREST UPON DEATH.

             2.3.1  Notice  of  Death.  Upon  the  death  of  the  Member,   the
representative  of the estate of the deceased Member shall promptly give written
notice of the death to the other Members, Rosenberg and Prime.

             2.3.2 Option to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days  after  receipt  of the  notice of death,  an option to
purchase all or any portion of the Membership  Interest of the deceased  Member,
for the price and upon the  other  terms  hereinafter  provided.  If the  Option
Members fail,  within such 30-day period,  to exercise their purchase option (by
delivery of written  notice)  with  respect to the  entirety of such  Membership
Interest,  the Option  Members  shall be deemed to have  elected not to exercise
their purchase option with respect to such unpurchased Membership Interest. Upon
any notice of  non-exercise  (or  deemed  non-exercise)  by the Option  Members,
Rosenberg (but not his estate if he is the deceased  Member) shall have, and may
exercise  within 30 days of  receipt of notice of such  non-exercise  (or deemed
non-exercise),  an option to  purchase  all or any  portion of such  unpurchased
Membership Interest for the price and upon the other terms hereinafter provided.
If Rosenberg fails,  within such 30-day period,  to exercise his purchase option
(by  delivery  of  written  notice)  with  respect  to  the  entire  unpurchased
Membership  Interest,  Rosenberg shall be deemed to have elected not to exercise
his purchase option with respect to any remaining Membership Interest.  Upon any
notice of non-exercise (or deemed non-exercise) by Rosenberg,  Prime shall have,
and may exercise  within 30 days of receipt of notice of such  non-exercise  (or
deemed  non-exercise),  an option to purchase all of such  remaining  Membership
Interest for the price and upon the other terms hereinafter provided.

2.4  OPTION UPON DEATH OF A MEMBER'S SPOUSE, TERMINATION OF MARITAL RELATIONSHIP
     OR PARTITION OF COMMUNITY PROPERTY.

             2.4.1  Death of  Member's  Spouse.  Each  Member and each  Member's
spouse  agree that in the event the spouse of a Member  predeceases  such Member
and such Member does not succeed by the spouse's  last will and  testament or by
operation of law to any interest  (including,  without  limitation,  a community
property interest) of the spouse in the Membership  Interest,  such Member shall
have, and may exercise  within 60 days after the death of the spouse,  an option
to purchase all or any portion of the  spouse's  interest for the price and upon
the other terms hereinafter  provided.  If the Member fails,  within such 60-day
period,  to exercise  his purchase  option (by delivery of written  notice) with
respect to the entirety of such spouse's  interest,  that Member shall be deemed
to have  elected  not to  exercise  his  purchase  option  with  respect to such
spouse's interest.  Upon any notice of non-exercise (or deemed  non-exercise) by
the Member,  the Option Members shall then have, and may exercise within 30 days
after  receipt  of such  non-exercise  (or  deemed  non-exercise),  an option to
purchase all or any portion of the deceased spouse's interest, for the price and
upon the other terms  hereinafter  provided.  If the Option Members fail, within
such 30-day period,  to exercise  their purchase  option (by delivery of written
notice) with respect to the entirety of such  deceased  spouse's  interest,  the
Option  Members shall be deemed to have elected not to exercise  their  purchase
option with respect to such unpurchased  deceased  spouse's  interest.  Upon any
notice of non-exercise (or deemed non-exercise) by the Option Members, Rosenberg
(if not the Member whose spouse is deceased) shall have, and may exercise within
30 days of receipt of notice of such non-exercise (or deemed  non-exercise),  an
option to purchase  all or any  portion of such  unpurchased  deceased  spouse's
interest  for the  price  and upon the  other  terms  hereinafter  provided.  If
Rosenberg fails,  within such 30-day period, to exercise his purchase option (by
delivery of written  notice)  with  respect to the entire  unpurchased  deceased
spouse's interest, Rosenberg shall be deemed to have elected not to exercise his
purchase option with respect to any remaining  portion of the deceased  spouse's
interest. Upon any notice of non-exercise (or deemed non-exercise) by Rosenberg,
Prime shall have,  and may exercise  within 30 days of receipt of notice of such
non-exercise  (or  deemed  non-exercise),  an  option  to  purchase  all of such
remaining  portion of the deceased  spouse's interest for the price and upon the
other terms hereinafter provided.

             2.4.2 Termination of Marital Relationship or Partition of Community
Property. In the event a divorce,  annulment or other proceeding for termination
of the  marital  relationship  is  filed by or  against  a  Member,  or upon the
initiation  of any voluntary or  involuntary  attempt to partition the community
property  estate between a Member and such Member's  spouse for any reason,  the
Member shall promptly give written notice to the other Members,  Rosenberg,  and
Prime, of such event.  The Member shall have, and may exercise within 60 days of
giving of such notice, an option to purchase all or any portion of the departing
spouse's interest in such Membership  Interest (including without limitation any
community  property interest,  for purposes of this Section),  for the price and
upon the other terms  hereinafter  provided.  If the Member  fails,  within such
60-day period,  to exercise his purchase  option (by delivery of written notice)
with respect to the  entirety of such  spouse's  interest,  that Member shall be
deemed to have elected not to exercise his purchase  option with respect to such
spouse's interest.  Upon any notice of non-exercise (or deemed  non-exercise) by
the Member,  the Option Members shall then have, and may exercise within 30 days
after  receipt  of such  non-exercise  (or  deemed  non-exercise),  an option to
purchase all or any portion of the departing  spouse's  interest,  for the price
and upon the other  terms  hereinafter  provided.  If the Option  Members  fail,
within such 30-day period,  to exercise  their  purchase  option (by delivery of
written  notice)  with  respect  to the  entirety  of  such  departing  spouse's
interest,  the Option  Members  shall be deemed to have  elected not to exercise
their  purchase  option  with  respect to such  unpurchased  departing  spouse's
interest. Upon any notice of non-exercise (or deemed non-exercise) by the Option
Members, Rosenberg (if not the Member whose spouse is departing) shall have, and
may exercise within 30 days of receipt of notice of such non-exercise (or deemed
non-exercise),  an option to  purchase  all or any  portion of such  unpurchased
departing  spouse's  interest for the price and upon the other terms hereinafter
provided.  If  Rosenberg  fails,  within such  30-day  period,  to exercise  his
purchase  option (by  delivery  of written  notice)  with  respect to the entire
unpurchased  departing  spouse's  interest,  Rosenberg  shall be  deemed to have
elected not to  exercise  his  purchase  option  with  respect to any  remaining
portion of the departing spouse's interest.  Upon any notice of non-exercise (or
deemed non-exercise) by Rosenberg,  Prime shall have, and may exercise within 30
days of receipt of notice of such  non-exercise  (or  deemed  non-exercise),  an
option to  purchase  all of such  remaining  portion of the  departing  spouse's
interest for the price and upon the other terms hereinafter provided.

2.5          ALTERNATE NOTICES.

             The failure of any  person,  whether a party to this  Agreement  or
otherwise,  to give notice of the occurrence of an Exercise Event (as defined in
Section 4.3) as contemplated herein shall not operate to prevent the creation of
any option which would otherwise arise pursuant to this ARTICLE II. Any party to
this  Agreement who has actual  knowledge of the occurrence of an Exercise Event
may give the required written notice of the occurrence of an Exercise Event, and
upon the giving of such written  notice the options  shall be created and become
exercisable  to the  same  extent  as if such  notice  was  given  by the  party
initially contemplated above. For instance, and purely by way of example, in the
event of the death of a Member,  another  Member having actual  knowledge of the
Member's  death  may give the  notice  initially  contemplated  to be given by a
representative  of the estate of the deceased  Member  pursuant to Section 2.3.1
above,  whereupon the Option  Members'  option  described in Section 2.3.2 would
arise and become  exercisable to the same extent as if the notice had been given
by the representative of the estate of the deceased Member.

                                   ARTICLE III

                   EXERCISE OF OPTIONS; EFFECT OF NON-EXERCISE

3.1          MANNER OF EXERCISE OF OPTIONS.

             All options granted in, or arising pursuant to, ARTICLE II shall be
exercised by a written notice to that effect  delivered within the time provided
for the exercise of the option.

3.2          COMPLETE EXERCISE OF OPTIONS.

             Notwithstanding  anything  herein to the  contrary,  the holders of
options granted in, or arising pursuant to, ARTICLE II must,  either alone or in
the  aggregate,  exercise the options in such a manner as to purchase all of the
Membership  Interest (or interest therein) subject to such options,  and failure
to do so shall cause a forfeiture of the options.

3.3          MULTIPLE OPTION HOLDERS.

             In cases  where an option is held by more than one  Option  Member,
each  purchasing  Option  Member  shall  be  entitled  to  purchase  his  or her
proportionate  share of the Membership Interest subject to the option. An Option
Member's  proportionate  share  shall  equal  the  total  amount  of  Membership
Interests  subject to the option multiplied by a fraction the numerator of which
is the  amount  of  Membership  Interests  held by such  Option  Member  and the
denominator  of which shall be the amount of  Membership  Interests  held by all
Option Members electing to exercise the option.

3.4          EFFECT OF NON-EXERCISE OF OPTIONS.

             If the  holders of options  granted  or  arising  pursuant  to this
Agreement do not exercise  their  options,  or such  options are  forfeited,  as
provided herein,  the person or persons  acquiring the Membership  Interests (or
interest  therein)  that  were  the  subject  of the  options  shall  execute  a
counterpart  of this  Agreement  and  become a party  hereto and shall hold such
Membership  Interests  subject to all the terms and conditions  provided herein,
and any transfer of such Membership  Interests (or interest  therein) shall only
be made in accordance  with the terms and  conditions  provided  herein.  In the
event the person or persons  acquiring  the  Membership  Interests  (or interest
therein)  fail to execute a  counterpart  of this  Agreement  and become a party
hereto,  such transfer shall be void and  ineffectual,  and shall not operate to
transfer any interest or title to the purported  transferee and such  Membership
Interests shall thereafter be subject to cancellation and  extinguishment by the
Company,  without  consideration  therefor.  In  addition,  in  the  event  of a
voluntary  transfer  subject to the provisions of Section 2.1, upon the lapse or
forfeiture of the options arising pursuant to that Section, the Member proposing
the  transfer  shall have the right to  effectuate  the  transfer of  Membership
Interests  in  accordance  with the  terms  stated  in the  notice  of intent to
transfer,  and the  transferee of such  Membership  Interests  shall execute and
become a party to this  Agreement  and  shall  hold  such  Membership  Interests
subject to all of its terms and conditions.  Provided further, however, any such
transfer of Membership  Interests shall be void and  ineffectual,  and shall not
operate to transfer any interest or title to the  purported  transferee,  if (i)
the  transfer  is not upon the terms or is not to the  transferee  stated in the
notice of intent to transfer,  or (ii) the transfer is not closed within 10 days
of receipt of written notice of the election not to exercise,  or the forfeiture
of, all applicable options.

                                   ARTICLE IV

                                 PURCHASE PRICE

4.1          PURCHASE PRICE.

             The  purchase  price of the  Membership  Interests  to be purchased
pursuant to options granted, held or exercised pursuant to Sections 2.2, 2.3 and
2.4  hereof,  shall be the amount  calculated  in  accordance  with  Section 4.2
hereof.

4.2          CALCULATION OF PURCHASE PRICE.

             When  determined in accordance  with this Section 4.2, the purchase
price for the Membership  Interest or any portion  thereof or spouse's  interest
therein shall be equal to the Appraised  Value of the Membership  Interest as of
the Valuation Date (as defined in Section 4.3 hereof), reduced when necessary to
reflect the purchase of less than a one hundred  percent (100%) interest in each
of the Membership Interests to be transferred (for example:  reduced by one-half
when a  spouse's  interest  is only an  undivided  one-half  community  property
interest in each of the Membership  Interests of a Member spouse).  For purposes
of this Agreement,  the "Appraised Value" of a Membership  Interest shall be (i)
based on the overall value of the Company as a going concern, expressed in a per
Membership Interest unit amount without  consideration to whether the Membership
Interest,  or interest therein,  being transferred  constitutes a controlling or
minority  interest in the Company,  and (ii) determined by a certified  business
appraiser,  selected  by the  Company,  that is a member of either the  American
Society of Appraisers or the Institute of Business  Appraisers;  but if a Member
or Prime  disagrees  with such  determination  that  Member or Prime may, at its
expense,  have another certified  business  appraiser that is a member of one or
both of the above named professional  organizations  determine the value, and if
the two appraisers cannot agree upon a value, they shall mutually select a third
certified  business  appraiser  (that  meets  the  above  described   membership
requirements) who shall,  together with the first two appraisers,  determine the
value of the  Membership  Interest by majority  vote.  The expense of such third
appraiser  shall  also be paid by the  Member or Prime,  as the case may be, who
disagrees  with the value  determination  of the Company's  original  appraiser,
unless the appraised value ultimately  determined is more than ten percent (10%)
greater than the value determined by the Company's original appraiser.

4.3          CERTAIN DEFINITIONS.

             As used herein,  the term "Valuation  Date" shall mean and refer to
the end of the fiscal year of the Company  immediately  preceding  the  Exercise
Event,  unless the purchasing party elects to use the alternate  valuation date,
in which  event the  Valuation  Date  shall be the end of the month  immediately
preceding the Exercise  Event. As used herein,  the term "Exercise  Event" shall
mean and refer to the event or  circumstance  described  in  ARTICLE  II of this
Agreement, as a result of which the Company, a Member, or Prime, as the case may
be in the first  instance,  becomes  entitled  to  exercise  a  purchase  option
hereunder.

                                    ARTICLE V

                          PAYMENT OF THE PURCHASE PRICE

5.1          PAYMENT.

             Except as otherwise  provided in this Agreement,  including Section
2.1, the purchase price for a Membership Interest to be purchased from a selling
party shall either: (i) be paid in cash; or (ii) at the option of the purchasing
party,  up to seventy  percent (70%) of the purchase  price may be deferred with
the remainder paid in cash at the closing.

5.2          PROMISSORY NOTE.

             If the purchasing  party elects to defer part of the purchase price
by the execution and delivery of a promissory  note, the deferred portion of the
price shall be evidenced by the promissory  note of the purchasing  party to the
order of the selling party payable in sixty (60) equal monthly  installments  of
principal  and interest on or before the first day of each month  beginning  the
month next following the date of closing. The interest rate for such installment
promissory  note shall be equal to the prime or base rate on corporate  loans at
large U.S.  money center  commercial  banks as  published  in the "Money  Rates"
column of the Wall  Street  Journal  on the date of  exercise  of the  option to
purchase  (or, if such option is not  exercised  on a date on which such rate is
published, the next following date on which such rate is published). In no event
shall the interest rate exceed the maximum legal  interest rate then  prevailing
for such obligations in the state of Texas. The note shall be secured by a first
lien security interest in the Membership Interest transferred and the purchasing
party shall  deliver  certificates  evidencing  the  Membership  Interest to the
selling party and take such further action as is reasonably necessary to perfect
the security interest.

                                   ARTICLE VI

                                   THE CLOSING

             Unless otherwise agreed by the parties, the closing of the sale and
purchase of a Membership  Interest shall take place at the principal  offices of
the Company within sixty (60) days after the exercise of any option  provided by
this Agreement.  Each party hereto  (including the spouses of the Members) shall
bear its own transaction  costs,  including  legal and accounting  fees, if any,
attributable to any transfer of a Membership Interest,  or any interest therein,
pursuant to this  Agreement.  Upon the closing,  the selling party shall deliver
its  Membership  Interest  to the  purchaser  free and  clear of all  liens  and
encumbrances,  and shall deliver to the Company its  resignation and that of all
of its nominees, if any, as officers and directors of the Company and any of the
Company's subsidiaries.  The selling party shall deliver to the purchasing party
at closing, all appropriate documents of transfer,  including without limitation
bills of sale, assignments or other instruments of conveyance. As a condition to
any closing of the sale and purchase of a  Membership  Interest (or any interest
therein) pursuant to this Agreement:  (i) the selling party shall be indemnified
by the purchasing party (in a form reasonably satisfactory to the selling party)
for all the Company's liabilities,  whether fixed or contingent,  to lenders and
others,  incurred prior to the closing of the  transaction,  (ii) the purchasing
party and/or the Company  shall cause the release of any personal  guaranties by
the  selling  party that the  selling  party may have  granted to the  Company's
lenders or other  creditors  or which may have  otherwise  been  provided by the
selling party for the benefit of the Company,  and (iii) if the selling party is
a creditor of the Company, the purchasing party shall unconditionally  guarantee
the debt of the Company to the  selling  party and execute  such  documents  and
instruments   of  guarantee  as  may  be  necessary  in  connection   therewith.
Furthermore,  and as a condition to closing, in the event the selling party owes
any amounts to the Company at the time of closing,  such  indebtedness  shall be
paid in full by the selling party at or prior to the closing, or may be deducted
from and offset  against the  purchase  price by the  purchasing  party,  in the
purchasing  party's  sole  discretion.  In the event of a failure  to close as a
result of the  non-satisfaction  of the  conditions to closing set forth herein,
this  Agreement  shall  remain  in full  force  and  effect  and all  Membership
Interests  shall remain  subject to the  restrictions  contained  herein and, in
addition,  the parties hereto shall be entitled to such other remedies as may be
available in the event the failure to close constitutes a breach hereof.

                                   ARTICLE VII

                             LEGEND ON CERTIFICATES

             All Membership  Interests now or hereafter owned by the Members, or
their  permitted  transferees,  shall  be  subject  to the  provisions  of  this
Agreement,  and any  certificates  representing  same shall  bear the  following
legend:

             "THE  MEMBERSHIP   INTEREST   REPRESENTED   HEREBY  AND  THE  SALE,
             ASSIGNMENT,  TRANSFER,  PLEDGE  OR OTHER  DISPOSITION  THEREOF  ARE
             SUBJECT TO CERTAIN RESTRICTIONS  CONTAINED IN A MEMBERSHIP INTEREST
             TRANSFER  RESTRICTION  AGREEMENT  AMONG THE  COMPANY AND THE WITHIN
             NAMED MEMBER, AND ANY AMENDMENT  THERETO.  THE AGREEMENT LIMITS THE
             USE OF THIS MEMBERSHIP  INTEREST AS COLLATERAL FOR ANY LOAN WHETHER
             BY PLEDGE,  HYPOTHECATION  OR OTHERWISE.  A COPY OF THE  MEMBERSHIP
             INTERES   TRANSFER   RESTRICTION   AGREEMENT  AND  ALL   APPLICABLE
             AMENDMENTS  THERETO  WILL BE FURNISHED BY THE COMPANY TO THE HOLDER
             HEREOF  WITHOUT  CHARGE UPON WRITTEN  REQUEST TO THE COMPANY AT ITS
             PRINCIPAL PLACE OF BUSINESS OR REGISTERED OFFICE."

                                  ARTICLE VIII

                            TERMINATION OF AGREEMENT

             This Agreement and all restrictions on Membership Interest transfer
created hereby shall terminate on the occurrence of any of the following events:

             (a)             The bankruptcy or dissolution of the Company.

     (b) The ownership by one person of all of the  Membership  Interests of the
Company which are then subject to this Agreement.

             (c) The execution of a written  instrument  by the Company,  all of
the Members who then own Membership  Interests  subject to this  Agreement,  and
Prime which terminates the same.

     (d) The date  twenty-one (21) years after the death of the last survivor of
all individuals who are parties to this Agreement.

                                   ARTICLE IX

                               GENERAL PROVISIONS

9.1          REMEDIES FOR BREACH.

             The  Membership  Interests are unique  chattels,  and each party to
this Agreement shall have the remedies which are available to him, her or it for
the violation of any of the terms of this Agreement,  including, but not limited
to, the equitable remedy of specific performance.

9.2          BINDING EFFECT.

             This  Agreement  is binding  upon and inures to the  benefit of the
Company,  its  successors  and  permitted  assigns,  to the  Members  and  their
respective heirs,  personal  representatives,  successors and permitted assigns,
and to Prime,  its successors and permitted  assigns.  This Agreement may not be
assigned,  in whole or in part, by any party hereto without the express  written
consent of all parties hereto.

9.3          PRIOR AGREEMENTS.

             This  Agreement  supersedes  all prior written and oral  agreements
between the parties regarding the subject matter hereof.

9.4          GOVERNING LAWS.

             This Agreement is executed under,  and in conformity with, the laws
of the State of Texas and shall be governed  thereby.  If any  provision of this
Agreement  shall be determined to be invalid or  unenforceable  or prohibited by
the laws of the State of Texas, this Agreement shall be considered  divisible as
to such provisions and such  provisions  shall be inoperative and shall not be a
part of the consideration  moving from any party to another party. The remaining
provisions  shall be valid and binding upon the parties and be of like effect as
though such invalid,  unenforceable  or prohibited  provisions were not included
herein.

9.5          AMENDMENT.

             This  Agreement  may be  amended  in whole  or in part  only by the
written consent of all the parties.  Such amendment shall be effective as of the
date then  determined by the parties and shall  supersede any provisions  herein
contained which are in conflict.

9.6          CAPTIONS AND GENDER.

             The captions and titles herein are for convenience only and are not
intended to include or  conclusively  define the subject matter of the text. All
pronouns and  references  thereto shall refer to the  masculine,  feminine,  and
neuter  genders,  singular  or plural,  as the  identification  of the  persons,
entities, and companies may require. The term "person" as used in this Agreement
shall include natural persons, companies,  partnerships, trusts, estates and any
other form of entity.

9.7          NOTICES.

             All notices  required to be given  hereunder  shall be deemed to be
duly given by  personally  delivering  such notice or by mailing it by certified
mail, to the Company,  to the Members,  and to Prime at the following  addresses
(which  may be  changed  by giving  written  notice of such  change to all other
parties hereto):

             To the Company: LASIK Investors, L.L.C.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Barnet:      Ronald W. Barnet, M.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Dulaney:     David D. Dulaney, M.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Rosenberg:   Mark Rosenberg
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Perkins:     Scott A. Perkins, M.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Pinkert:     Robert B. Pinkert, O.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Prime:        Prime Medical Operations, Inc.
                              Attention: President
                              1301 Capital of Texas Highway
                              Austin, Texas 78746

9.8  BINDING EFFECT OF THIS AGREEMENT ON ADDITIONAL MEMBERSHIP INTEREST ACQUIRED
     BY A MEMBER.

             In the event a Member acquires,  contracts to acquire,  or receives
any Membership  Interests of the Company which are not subject to this Agreement
at the time of acquisition,  such additional  Membership Interests of the Member
shall  be   automatically   subject  to  this  Agreement  and  any  certificates
representing  such Membership  Interests shall bear the legend prescribed herein
and this Agreement shall be amended, if necessary, to reflect the acquisition of
such Membership Interests by the Member.

9.9          EXECUTION OF DOCUMENTS.

             Whenever Membership Interests are to be purchased by the Company, a
Member, or Prime pursuant to this Agreement,  the transferor shall do all things
and execute and deliver all documents and make all transfers as may be necessary
to consummate such purchase.  In the event that the transferor  refuses to abide
by the terms and  conditions  specified  herein,  the  purchaser(s)  may  tender
payment  for such  Membership  Interest by mailing  payment to the  transferor's
attention  at the  address  of the  Company's  registered  office on file at the
office of the Texas Secretary of State.  After payment is tendered  accordingly,
the Company shall be entitled to cancel such  Membership  Interest on its books,
and reissue such Membership Interest to the purchaser(s) or, if the purchaser is
the Company,  the Company may hold such Membership Interest as treasury stock or
cancel such Membership Interest.

9.10         ACTIONS BY THE COMPANY.

             Any decision by the Company to exercise any purchase  option,  give
any notice or otherwise enforce any provisions of this Agreement,  shall be made
by a majority  vote of Members who are not then in breach of this  Agreement and
whose Membership Interests are not then the subject of any option or requirement
of notice of an Exercise Event.

                            [Signature pages follow]


<PAGE>
                                SIGNATURE PAGE TO

                               MEMBERSHIP INTEREST

                         TRANSFER RESTRICTION AGREEMENT

             EXECUTED as of the date first mentioned above.

             COMPANY:                        LASIK Investors, L.L.C.

                                             By:
                                                 Ronald W. Barnet, M.D., manager

                                             By:
                                                 David D. Dulaney, M.D., manager

             BARNET:

                                                 Ronald W. Barnet, M.D.


             DULANEY:

                                                 David D. Dulaney, M.D.

             ROSENBERG:

                                                 Mark Rosenberg

             Perkins:

                                                 Scott A. Perkins, M.D.


             Pinkert:

                                                 Robert B. Pinkert, O.D.


             PRIME:                              Prime Medical Operating, Inc.

                                             By:
                                                 Printed Name:
                                                 Title:



<PAGE>


                                SPOUSAL CONSENTS

             The  undersigned   spouse  of  Ronald  W.  Barnet,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                                         Signature:
                                                         Printed Name:

             The  undersigned   spouse  of  David  D.  Dulaney,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                                         Signature:
                                                         Printed Name:

             The undersigned  spouse of Mark Rosenberg  hereunto  subscribes her
name in evidence of her  agreement  and consent to the  disposition  made of any
interest  she may have,  including  any  community  property  interests,  in the
membership  interest of LASIK  Investors,  L.L.C.,  referred to in the foregoing
Agreement, and to all other provisions of such Agreement.

                                                         Signature:
                                                         Printed Name:

             The  undersigned   spouse  of  Scott  A.  Perkins,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                                         Signature:
                                                         Printed Name:

             The  undersigned  spouse  of  Robert  B.  Pinkert,   O.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                                         Signature:
                                                         Printed Name:

<PAGE>
                                   EXHIBIT-I

                                               COLLOCATION AGREEMENT

                                                  BY AND BETWEEN

                                        BARNET DULANEY EYE CENTER, P.L.L.C.

                                                        AND

                                          PRIME/BDEC ACQUISITION, L.L.C.






<PAGE>


                                                    COLLOCATION
                                                     AGREEMENT

     This COLLOCATION  AGREEMENT  ("Agreement"),  effective as of the 1st day of
September,  1999 (the  "Effective  Time"),  is by and between BARNET DULANEY EYE
CENTER,  P.L.L.C.,  an Arizona  professional limited liability company ("BDEC"),
and  PRIME/BDEC  ACQUISITION,  L.L.C.,  a  Delaware  limited  liability  company
("Company").

                                               W I T N E S S E T H:

     WHEREAS,  the  Company  has been  organized  for the  purpose of  providing
facilities,  equipment  and  non-physician  personnel  for  the  performance  by
physicians  of  Refractive  Surgery  (as  defined  herein),  for the  marketing,
scheduling  and  management of Refractive  Surgery,  for the  credentialing  and
scheduling  of  physicians  to perform  Refractive  Surgery and for the billing,
collecting  and   accounting  for  the  use  of  the  facility,   equipment  and
non-physician personnel (the "Business");

     WHEREAS,  BDEC has owned or leased assets for the performance by physicians
of Refractive Surgery, including, without limitation, certain space located in a
building at 4800 North 22nd Street,  Phoenix,  Arizona  85016 and certain  space
located in a building at 555 East River Road,  Tucson,  Arizona  (individually a
"Facility"  and  collectively  the  "Facilities")  and in  connection  with each
Facility, equipment,  instruments, computer software used in connection with the
equipment, certain leases and contracts, the leasehold improvements,  furniture,
fixtures and other fixed assets and items of personal property used primarily in
or  materially  relied  on  for  the  performance  of  Refractive  Surgery  (the
"Equipment and Personalty");

     WHEREAS, BDEC employs  non-physician  personnel (the "BDEC Employees") with
expertise  and  experience  in  assisting   physicians  in  the  performance  of
Refractive  Surgery,   in  credentialing  and  scheduling   physicians  for  the
performance  of  Refractive  Surgery  in  the  Facilities,   in  performing  the
scheduling of patients for Refractive  Surgery in the Facilities,  in performing
marketing,  accounting,  billing  and  collection  services  for  the use of the
Facilities  and in managing  the  Facilities  and all  non-physician  aspects of
Refractive Surgery in the Facilities (the "Support Services");

     WHEREAS,   BDEC  employs  physician  and   non-physician   executives  (the
"Managers")  with expertise and experience in the management of the  Facilities,
the Equipment and Personalty,  the Support  Services and all other elements of a
Refractive Surgery center (the "Management Services");

     WHEREAS,  BDEC, Prime Medical  Operating,  Inc.("Prime") and others entered
into that certain Contribution  Agreement dated effective September 1, 1999 (the
"Contribution  Agreement"),  pursuant  to  which  Prime,  BDEC and  others  have
participated in a series of transactions that were completed simultaneously with
the execution and delivery of this Agreement,  in which transactions the Company
became the owner of the  Equipment  and  Personalty  and the business  conducted
therewith,  excluding the practice of medicine,  and in which  transactions BDEC
agreed to provide to the Company the  Facility and the  Management  Services and
Support Services on the terms and conditions set forth in this Agreement;

     NOW, THEREFORE,  for and in consideration of the mutual covenants set forth
herein, and other good and valuable  consideration,  the receipt and adequacy of
which are hereby forever acknowledged and confessed, the parties hereto agree as
follows:

                                                     ARTICLE I
                                                    DEFINITIONS

     1.1 Agreement shall mean this Collocation Agreement between the Company and
BDEC  and  any  amendments  hereto  as may  from  time to  time  be  adopted  as
hereinafter provided.

     1.2 BDEC shall mean Barnet Dulaney Eye Center, P.L.L.C.

     1.3 Buildings shall mean Building P and Building T.

     1.4 Building P shall mean the  building  located at 4800 North 22nd Street,
Phoenix, Arizona 85016, and known generally as the Barnet Dulaney Eye Center.

     1.5  Building T shall  mean the  building  located at 555 East River  Road,
Tucson, Arizona, and known generally as the Barnet Dulaney Eye Center.

     1.6  Business  shall  mean  the  provision  of  facilities,  equipment  and
non-physician  personnel for the performance by physicians of Refractive Surgery
(as defined  herein),  the  marketing,  scheduling  and management of Refractive
Surgery,  the credentialing  and scheduling of physicians to perform  Refractive
Surgery and the billing,  collecting and accounting for the use of the facility,
equipment and non-physician personnel.

         1.7 Business  Expense shall mean all  out-of-pocket  costs and expenses
incurred by BDEC solely and  exclusively  in the  performance  of its duties and
obligations  under,  and in accordance  with, this Agreement.  Business  Expense
shall also  include  that portion  (allocated  based on the relative  percentage
amount of each such  employee's  time spent working  directly on the Business of
the Company) of salaries,  wages and  benefits for those  personnel  employed by
BDEC to provide  services  hereunder,  but only to the extent such employees (i)
work  directly on the  Business  of the  Company  and (ii) are either  listed on
Exhibit B hereto or are  subsequently  employed to replace such listed employees
or are  added  in the  same  service  categories  related  to  the  Business  as
corresponds  to the service  categories  applicable to the  employees  listed on
Exhibit B. Business  Expense  shall also include a reasonable  allocation of the
out-of-pocket   costs  incurred  by  BDEC  related  to  hiring  such  personnel.
Notwithstanding the foregoing, Business Expense shall not include any portion of
the salaries,  wages or benefits related to any personnel  employed or otherwise
retained or contracted by BDEC who work in any of the following  departments  or
fall  within any of the  following  categories:  (a)  accounting,  (b)  accounts
receivable,  (c) purchasing, (d) practice operations, (e) management information
systems and facilities support, (f) human resources,  (g) credentialing,  or (h)
executive management.  Furthermore,  Business Expense shall not include any rent
or other costs or expenses  incurred by BDEC  pursuant to the Base  Leases.  For
illustration  purposes,  the parties agree that Business Expense for the Phoenix
Refractive  Surgery  center  based on the pro forma  annualized  facility  model
attached  hereto  as  Exhibit  A for the  first  full  year of the  Term of this
Agreement  would be  $1,663,638,  being the sum of the  categories  on Exhibit A
marked  with an  asterisk.  It is the  intention  of the parties  that  Business
Expense be consistent with the methodology reflected in Exhibit A.

     1.8 Company shall mean Prime/BDEC Acquisition, L.L.C.

     1.9  Facility  and  Facilities  shall have the  meaning  given to it in the
recitals to this Agreement.

     1.10 Premises P shall mean the Facility and other space located in Building
P to which the right to use is granted in Section 2.3 hereof.

     1.11 Premises T shall mean the Facility and other space located in Building
T to which the right to use is granted in Section 2.3 hereof.

     1.12 Refractive Surgery shall mean, collectively, any current and/or future
surgical procedures intended to correct myopia,  hyperopia or astigmatism of the
eye, excluding procedures aimed only at restoring accommodation (presbyopia) and
procedures  to  treat  only  cataracts,   glaucoma,   oculoplastics  or  retinal
abnormality.

     1.13 Services Fee shall mean BDEC's compensation  established and described
in Article VI hereof.

     1.14 State shall mean the State of Arizona.

     1.15 Term shall mean the  initial  and any  renewal  periods of duration of
this Agreement as described herein.

                                                ARTICLE II
                                             RIGHT TO USE THE PREMISES

     2.1 Base Lease.  Section 2.3  contains a grant of a right to use Premises P
and Premises T and is subject and  subordinate  to the terms and  conditions  of
those certain  leases as amended ("Base  Leases")  pursuant to which BDEC leases
the Building P and Building T.

     2.2 Users of  Buildings.  Building P and  Building T are used for  multiple
activities, including, but not limited to, Refractive Surgery, office and clinic
activities of BDEC  physicians and other  professionals,  an ambulatory  surgery
center ("ASC") and marketing,  accounting,  management and other  administrative
activities.  The various  activities  in each Building do not  necessarily  have
specific or identified space and, in some instances, more than one activity uses
a space at the same time or at different times.  BDEC designates,  schedules and
modifies  the  location  and the times that each  activity  can use space in the
Buildings.

         2.3 Grant of Right to Use. In  consideration  of  Company's  payment to
BDEC of the Purchase Price, as defined in the Contribution Agreement, and on the
terms and  conditions of this  Agreement,  BDEC hereby grants to the Company the
non-exclusive  right to use for  Refractive  Surgery the spaces in the Buildings
where the  Equipment  and  Personalty  are located at the times  during  regular
business  hours and in the manner  designated by BDEC (but in no event less than
forty percent (40%) of the of the business hours during each week),  which might
require the using of such space while the same or adjoining  space is being used
by an ASC or on a  cooperative  schedule  with an ASC.  BDEC also  grants to the
Company the non-exclusive  right to use and to permit its guests and invitees to
use the common areas in accordance  with the Base Leases.  Notwithstanding  that
the foregoing grants are  non-exclusive,  BDEC covenants and agrees that it will
not allow any person or entity,  other than the Company, to utilize any space in
the  Buildings,  any Equipment and Personalty or any BDEC Employees for purposes
of conducting any component of the Business.

     2.4 Term and Conditions of Grant. The grants set forth in Section 2.3 above
are each for the term and on the conditions, requirements,  covenants, rules and
regulations  of the Base Leases and subject to  Company's  paying its  allocated
portion of the rent,  common area  charges and other  payments  required of BDEC
under the Base Leases.

     2.5 Maintenance of Base Leases. Throughout the Term of this Agreement, BDEC
covenants  and agrees to  maintain  all Base  Leases in full  force and  affect,
without any breach or default by BDEC thereunder.

                                                    ARTICLE III
                                         APPOINTMENT AND AUTHORITY OF BDEC

     3.1 Appointment. The Company hereby appoints BDEC as its sole and exclusive
agent  for the  management  and  performance  of  day-to-day  operations  of the
Business in the  Facilities,  using the  Equipment and  Personalty,  through the
provision of Management  Services and Support Services,  as defined herein,  and
BDEC hereby accepts such appointment,  subject at all times to the provisions of
this Agreement.

         3.2  Authority.  Consistent  with  the  provisions  of this  Agreement,
directions given by the Company and operating and capital budgets established by
the Company,  BDEC shall have the responsibility  and commensurate  authority to
provide,  or  cause  to be  provided,  personnel,  business  and  administrative
services  for the  Company,  which shall  include  those  services  set forth in
Article  III hereof.  BDEC is hereby  expressly  authorized  to provide all such
services  in  whatever  manner  BDEC,  in  good  faith,  deems  appropriate  and
consistent  with  commercially  reasonable  standards  to  meet  the  day-to-day
requirements  of  the  business  functions  of the  Company  or  related  to the
Business.  The  authority  of BDEC  shall  extend no further  than is  expressly
provided  herein,  and  shall  not be  extended  by  implication  or  otherwise.
Notwithstanding  anything  contained herein to the contrary,  BDEC shall have no
authority  to speak on behalf of, or to bind,  the Company  with  respect to any
third party.

     3.3 Retained Authority.  The Company shall at all times retain the ultimate
responsibility  for the  operation of the Business  and,  except as delegated to
BDEC herein or by resolution of Company's  managers,  shall retain the authority
and power and to make all decisions with respect to its assets and rights.

     3.4  Nature of  Relationship.  The  parties  acknowledge  and agree that no
partnership  or other form of entity,  or any joint and  several  liability,  is
intended to be created by or between them by the  execution or operation of this
Agreement, and none of the foregoing should be implied.

                                                    ARTICLE IV
                                                 COVENANTS OF BDEC

     4.1  Management  and Support  Services.  BDEC shall provide the  Management
Services  and  Support  Services  necessary  to operate  the  Business as it was
operated by BDEC prior to the Effective Time, including,  but not limited to the
following:

     4.1.1 Marketing and Scheduling.  BDEC shall conduct  marketing  efforts for
the Facility and shall schedule patient treatment in the Facility, in the manner
that such services were performed prior to the Effective Time.

     4.1.2  Physician  Matters.  BDEC  shall  credential  physicians  to perform
Refractive  Surgery in the Facility  and shall  schedule  physicians  to use the
Facility in the manner that such services were performed  prior to the Effective
Time.

     4.1.3 Supplies.  As agent for the Company, BDEC shall obtain all reasonable
medical,  office, and other supplies,  including stationery and forms, and shall
ensure that the Company is at all times adequately stocked with such supplies as
are reasonably necessary and appropriate for the operation of the Business.

     4.1.4  Licenses and Permits.  BDEC shall  coordinate  all  development  and
planning  processes,  and apply for and use  BDEC's  best  efforts to obtain and
maintain all federal,  state, and local licenses and regulatory permits required
for or in connection with the operation of the Business.

     4.1.5 Contract  Negotiations.  BDEC shall negotiate,  either directly or on
the Company's  behalf, as appropriate,  all contractual  arrangements with third
parties as are reasonably necessary and appropriate for the Business.

                  4.1.6 Financial  Matters.  BDEC shall establish and administer
accounting procedures,  controls, and systems for the development,  preparation,
and safekeeping of records and books of accounts relating to the Company, all of
which shall be prepared and  maintained in accordance  with  generally  accepted
accounting  principles  consistently  applied. BDEC shall prepare and deliver to
the Company,  and each of its members,  within thirty (30) days after the end of
each fiscal year of the Company,  a balance sheet, a profit and loss  statement,
and a  statement  of sources  and  applications  of funds and changes in working
capital reflecting the financial status of the Company and as of the end of such
prior fiscal year,  all of which shall be prepared in accordance  with generally
accepted accounting principles  consistently applied.  Additionally,  BDEC shall
prepare and deliver to the board of  managers  of the  Company,  and each of the
Company's members,  monthly financial  statements within ten (10) days after the
end of each month, and shall prepare and deliver to the board of managers of the
Company,  and each of the Company's members,  such other financial statements or
records  as BDEC may  from  time to time  deem  appropriate  or as the  board of
managers of the Company,  or its members,  may reasonably  request. On or before
ninety (90) days prior to the end of each fiscal year of the Company,  BDEC will
prepare and deliver to the board of  managers  of the  Company,  and each of the
Company's  members,  a  proposed  operating  budget of  projected  expenses  and
revenues  of  the  Company  for  the  next  fiscal  year  of  the  Company,  and
representatives of BDEC shall make themselves  reasonably available to the board
of managers and the members of the Company to explain such  proposed  budget and
the underlying assumptions.

     4.1.7 Billing and Collection.  BDEC shall be solely responsible for billing
and  collecting  for all  services  provided  by Company  and for the use of the
Facility and Equipment and  Personalty.  Company shall be entitled to all monies
collected by BDEC on behalf of Company.

     4.1.8 Information Systems.  BDEC shall provide and maintain the information
systems it deems  necessary to operate the Business.  BDEC shall have reasonable
discretion to select hardware and software,  provided such hardware and software
shall be adequate to operate the Business in a commercially  reasonable  manner,
and BDEC  shall be  responsible  for  training  employees  to  operate  any such
systems.

     4.1.9 Legal  Actions.  As requested  by the Company,  BDEC shall advise and
assist the Company in instituting  or defending  legal actions or proceedings by
or  against  third  parties  arising  out of the  Business,  including,  without
limitation,  those actions necessary for the protection and continued  operation
of the Company.  BDEC shall have no authority to initiate,  compromise or settle
any legal  action in the name of the  Company,  or to confess a judgment  in the
name of, or on behalf of, the Company.

     4.1.10  Insurance.  (a) BDEC shall  obtain and  maintain  professional  and
comprehensive  general liability  insurance and other insurance covering Company
for the  risks  and in the  amounts  typically  carried  by  others  in the same
business as Company.

     (b) BDEC  shall  obtain  and  maintain  appropriate  workers'  compensation
coverage for BDEC's  personnel and shall carry  professional  and  comprehensive
general  liability  insurance  covering all BDEC  personnel in amounts that BDEC
deems necessary, the cost of which insurance shall be a Business Expense.

         4.2  Personnel.  BDEC shall  employ or otherwise  retain,  and shall be
responsible  for  interviewing,   selecting,   hiring,  training,   supervising,
scheduling,  and terminating,  non-physician  personnel as BDEC deems reasonably
necessary and appropriate for the performance of Management Services and Support
Services.  Such personnel may include  temporary or "floater"  personnel who are
retained by BDEC to  substitute  for permanent  personnel.  BDEC shall have sole
responsibility  for determining the salaries,  wages, and fringe benefits of all
such  personnel,  for paying such  salaries and wages,  and for  providing  such
fringe benefits,  and for  withholding,  as required by law, any sums for income
tax, unemployment insurance,  social security, or any other withholding required
by applicable law or governmental  requirement.  BDEC shall have sole discretion
in decisions  regarding the termination of personnel employed by BDEC to provide
services  to the  Company.  BDEC shall  indemnify  the  Company and the Compan s
managers and members and hold them  harmless from and against any claim or cause
of action  which  alleges  or is based upon any act or  omission  by BDEC or its
owners, managers,  directors, officers or employees with respect to any employee
or  former  employee  of BDEC.  This  indemnity  obligation  shall  survive  any
termination or expiration of this Agreement.

          4.2.1  Non-Exclusivity.  In recognition of the fact that the personnel
     retained by BDEC to provide  services  pursuant to this  Agreement may from
     time to time perform services for others,  this Agreement shall not prevent
     BDEC from  performing  such services for others or restrict BDEC from using
     such  personnel in the  performance of services for other parties which are
     not in the same business as Company.

                  4.2.2 Equal Employment Opportunity.  Without limitation of any
provision set forth herein,  BDEC expressly agrees,  for itself and on behalf of
the  Company,  to abide by any and all  applicable  federal  and/or  State equal
employment  opportunity  statutes,  rules, and regulations,  including,  without
limitation,  Title VII of the Civil  Rights  Act of 1964,  the Equal  Employment
Opportunity Act of 1972, the Age  Discrimination  in Employment Act of 1967, the
Equal  Pay Act of 1963,  the  National  Labor  Relations  Act,  the  Fair  Labor
Standards  Act, the  Rehabilitation  Act of 1973,  the  Occupational  Safety and
Health Act of 1970,  and the Americans  with  Disabilities  Act, all as may from
time-to-time be modified or amended.

          4.2.3  Labor  Reports.  BDEC shall for its own account or on behalf of
     the Company,  as  appropriate,  prepare,  maintain,  and file all requisite
     reports and  statements  regarding  income tax  withholdings,  unemployment
     insurance,  social  security,   workers'  compensation,   equal  employment
     opportunity,  or other  reports and  statements  required  with  respect to
     personnel  provided by BDEC pursuant to this  Agreement and with respect to
     all personnel employed or otherwise retained by the Company.

          4.3 Conduct of Business.  BDEC  represents and warrants to the Company
     that it is  authorized  to enter into and perform  this  Agreement  and its
     duties  hereunder  without the consent or approval of any third party which
     has not been  obtained.  BDEC  covenants  and agrees to provide  all of the
     services  required of it hereunder,  and to perform all of its  obligations
     hereunder,  in a commercially  reasonable manner and in compliance with all
     applicable laws and legal requirements.

                                                   ARTICLE V y'
                                              COVENANTS OF COMPANY y'

          5.1 Notices to BDEC. Company will give BDEC timely notice of operating
     and capital budgets approved by the Company and directions or requests that
     it has with  respect to the conduct of the  Business or the manner in which
     BDEC  performs  its  duties  hereunder  in order  that BDEC  shall  have an
     opportunity to comply with such budgets, directions or requests.

         5.2 Invoices and Payment.  BDEC shall  deliver to the board of managers
of the  Company,  and to each of the members of the  Company,  monthly  invoices
setting forth the Services Fee, Use Fees, and expense reimbursement due BDEC for
the immediately preceding month, together with such supporting  documentation as
shall be reasonably necessary to document the calculation and incurrence of such
amounts in accordance with the terms of this Agreement. The Company will pay, or
authorize BDEC in writing to pay, the invoiced  amounts  properly due within ten
(10)  days  after  receipt  of such  invoice,  unless  any of such  amounts  are
contested in good faith.

                                                   ARTICLE VI y'
                                             FINANCIAL ARRANGEMENT y'

          6.1 Amount of Services Fee. As  compensation  (the "Services Fee") for
     the Management Services and Support Services to be rendered hereunder, BDEC
     shall be  entitled  to  receive  from the  Company  an amount  equal to Two
     percent (2%) of the Company's Net Revenues (as hereinafter defined).

         6.2  Determination  of Net Revenues.  For purposes of Section 6.1, "Net
Revenues" shall mean the total operating  revenues of the Company net of revenue
deductions  which  include  without  limitation  an  allowance  for  contractual
allowances,  discounts,  professional fees, co-management fees and staff managed
fees and other uncollectible  amounts,  all as determined in accordance with the
methodology  used in the  preparation  of  Exhibit  A hereto  and  otherwise  in
accordance with generally accepted accounting  principles  consistently applied.
For illustration  purposes,  the parties agree that Net Revenues for the Phoenix
Refractive  Surgery  center  based on the pro forma  annualized  facility  model
attached  hereto  as  Exhibit  A for the  first  full  year of the  Term of this
Agreement would be $5,968,627.

          6.3 Business  Expenses.  In addition to the Services Fee  described in
     Section 6.1, the Company shall  reimburse  BDEC, upon submission by BDEC of
     an invoice and necessary supporting documentation, for any Business Expense
     properly incurred by BDEC in accordance with this Agreement.

          6.4 Use Payment.  Company agrees to pay (the "Use Payment") to BDEC on
     a monthly basis as compensation for BDEC's grant to Company of the right to
     use the Premises and common areas of the Buildings. The Use Payment for the
     Premises in Building P shall be twelve percent (12%),  and for the Premises
     in Building T shall be  thirty-six  percent (36%) of the rent and all other
     costs and expenses  incurred by BDEC pursuant to the Base Lease for each of
     the respective building. The Use Payment shall be paid in advance and shall
     be due and payable on the first day of each month during the Term.


                                                  ARTICLE VII y'
                                              TERM AND TERMINATION y'

          7.1 Term. This Agreement shall be effective for an initial period (the
     "Term") commencing on the Effective Date and ending September 1, 2004.

          7.2 Termination.  The Company may terminate this Agreement immediately
     upon the occurrence of one of the following events:

                         (1) the dissolution or bankruptcy of BDEC; or

                         (2) after the expiration of a ninety (90) day period in
                    which BDEC has failed to remedy its  failure to perform  its
                    duties under this Agreement  after having  received  written
                    notice  from the  Company of BDEC's  failure to perform  its
                    duties under this  Agreement,  which notice must specify the
                    failure to perform.

     7.3  Termination  by  Agreement.  In the event the  Company  and BDEC shall
mutually  agree  in  writing,  this  Agreement  may be  terminated  on the  date
specified in such written agreement.

         7.4 Effects of  Termination.  Upon  termination of this  Agreement,  as
hereinabove  provided,  no party  shall have any further  obligations  hereunder
except for (i) obligations  accruing prior to the date of termination,  and (ii)
obligations,  promises, or covenants set forth herein that are expressly made to
extend beyond the Term, including, without limitation,  payment of accrued money
due under  Article VI, if any, and the  authority  and limited power of attorney
granted to BDEC herein, which shall survive until such time as such obligations,
promises,  or  covenants  shall  be  fully  paid  and  satisfied  (all of  which
provisions  shall survive the  expiration  or  termination  of this  Agreement).
Notwithstanding  anything  to the  contrary  herein,  upon  termination  of this
Agreement for any reason,  all accrued Service Fees,  Business  Expenses and Use
Payments,  if any,  shall  become  immediately  due and payable to BDEC  without
demand or notice.

                                                  ARTICLE VIII
                                                  MISCELLANEOUS

     8.1 Notices. Any notice, request, demand,  instruction,  communication,  or
other document required, permitted, or desired to be given hereunder shall be in
writing  and,  except  as  otherwise  provided  for  herein,   shall  be  deemed
effectively  given:  (a) on receipt if  delivered  personally  or by  commercial
courier service or if sent by prepaid telex,  telegram, by facsimile or by other
instantaneous  electronic  transmission  device,  or (b) on the  fifth day after
deposit (unless a different date is shown on the return receipt) if sent postage
prepaid registered or certified United States mail, return receipt requested, as
follows:

                  Company:                  Prime/BDEC Acquisition, L.L.C.
                                            1301 Capital of Texas Highway
                                            Suite C-300
                                            Austin, Texas 78746
                                            Attn.:            President
                                            Facsimile:  (512) 314-4398

                  BDEC:                     Barnet Dulaney Eye Center, P.L.L.C.
                                            4800 North 22nd Street
                                            Phoenix, Arizona  85016
                                            Attn.: Mark Rosenberg
                                            Facsimile:  (602) 508-4889

or to such other  address,  or to the attention of such other person or officer,
as either party may by written notice designate.

     8.2 Governing  Law. This  Agreement has been executed and delivered in, and
shall be governed by, and construed and enforced in accordance with, the laws of
the State of Texas.  Proper venue for any action with respect to this  Agreement
shall be Dallas County, Texas.

       8.3 Assignment.  Except as may be herein  specifically  provided to the
contrary,  this Agreement  shall inure to the benefit of and be binding upon the
parties  hereto and their  respective  legal  representatives,  successors,  and
assigns;  provided,  however,  that  neither  party may  assign  its  rights and
obligations under this Agreement without the prior written consent of the other.

     8.4 No Waiver.  The failure of either  party to insist at any time upon the
strict  observance  or  performance  of any  provision  of this  Agreement or to
exercise any right or remedy as provided in this Agreement  shall not impair any
right or  remedy of such  party or be  construed  as a waiver or  relinquishment
thereof with respect to subsequent defaults or breaches.  Every right and remedy
given by this Agreement to the parties hereto may be exercised from time to time
and as often as may be deemed expedient by the appropriate party.

     8.5  Consents,  Approvals,  and  Exercise of  Discretion.  Except as may be
herein specifically  provided to the contrary,  whenever this Agreement requires
any consent or approval to be given by either party, or either party must or may
exercise  discretion,  the parties agree that such consent or approval shall not
be unreasonably  withheld or delayed,  and such  discretion  shall be reasonably
exercised.


     8.6  Severability.  In the event any provision of this Agreement is held to
be invalid,  illegal,  or unenforceable for any reason and in any respect,  such
invalidity,  illegality,  or unenforceability  shall not affect the remainder of
this  Agreement,  if the remainder of this  Agreement can be enforced to achieve
its purposes equitably to both parties.

     8.7 Divisions and Headings.  The division of this  Agreement into articles,
sections,  and  subsections  and the use of captions and headings in  connection
therewith are solely for convenience and shall not affect in any way the meaning
or interpretation of this Agreement.

         8.8 Sales and Use Tax. BDEC and the Company  acknowledge and agree that
certain of the services to be provided by BDEC hereunder may be subject to state
sales and use taxes and that BDEC may have a legal  obligation  to collect  such
taxes from the Company and to remit same to the State. The Company agrees to pay
the  applicable  state  sales and use taxes in  respect  of the  portion  of the
Services  Fee  attributable  to such  services,  and  grants  BDEC the  right to
withdraw and disburse from the bank accounts of the Company amounts necessary to
timely and fully pay such taxes.

         8.9  Entire  Agreement.  With  respect  to the  subject  matter of this
Agreement,  this Agreement supersedes all previous contracts and constitutes the
entire  agreement  between  the  parties.  Neither  party  shall be  entitled to
benefits other than those specified  herein. No oral statements or prior written
material not specifically  incorporated herein shall be of any force and effect,
and no changes in or  additions to this  Agreement  shall be  recognized  unless
incorporated  herein by amendment  in writing and signed by all parties  hereto.
Such  amendment(s)  shall  become  effective  on the  date  stipulated  in  such
amendment(s).  The parties  specifically  acknowledge that, in entering into and
executing this Agreement,  the parties rely solely upon the  representations and
agreements contained in this Agreement and no others.

         8.10 Audit Rights.  During the Term of this  Agreement and for a period
of two (2) years after any  termination  or  expiration of this  Agreement,  the
Company and each of its members shall be entitled to audit and inspect the books
and records of BDEC for purposes of  determining  the  propriety of all Business
Expenses,  Services  Fees and Use  Payments  charged to the  Company  under this
Agreement.  BDEC agrees to maintain,  throughout such period,  detailed  records
supporting  all amounts  charged to, or reimbursed  by, the Company  pursuant to
this  Agreement  and to  cooperate  fully with,  and to make its  employees  and
records  available  during  normal  business  hours to,  the  auditors  or other
representatives  of the Company or its  members  performing  such  audit.  Audit
rights may not be exercised  more  frequently  than once in every  eighteen (18)
month period and all costs and expenses  associated  therewith shall be borne by
the party  exercising  audit rights unless any such inspection  reveals that the
Company has overpaid,  by at least  $25,000,  any amounts which should have been
properly  paid or  reimbursed  to BDEC in  accordance  with  the  terms  of this
Agreement.  BDEC shall be entitled  to receive at least  thirty (30) days' prior
written  notice of the exercise of audit  rights prior to the  beginning of such
inspection.

                                             [Signature page follows]




<PAGE>





                                                 SIGNATURE PAGE TO
                                               COLLOCATION AGREEMENT


     IN WITNESS WHEREOF, the parties have executed this Agreement as of the date
first written above.


     COMPANY:                        PRIME/BDEC ACQUISITION, L.L.C.


                                     By: _______________________________________

                                     Name: _____________________________________

                                     Title: ____________________________________



     BDEC:                           BARNET DULANEY EYE CENTER, P.L.L.C.


                                     By: ______________________________________
                                     Ronald W. Barnet, M.D., manager


                                     By: ______________________________________
                                     David D. Dulaney, M.D., manager





<PAGE>





















                                                     EXHIBIT A

                                               Pro Forma Annualized
                                                  Facility Model




<PAGE>




                                                     EXHIBIT B

                                                     EMPLOYEES





<PAGE>


                                    EXHIBIT J

                                     FORM OF

                              CONSULTING AGREEMENT

         This Consulting  Agreement (this  "Agreement") is made and entered into
as of  September  1, 1999  (the  "Effective  Date"),  by and  between  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability  company (the "Company") and
____________________________ (the "Consultant").

         For good and valuable  consideration,  the receipt and  sufficiency  of
which is hereby acknowledged, the parties hereto agree as follows:

     1.  BACKGROUND.  This  Agreement  is entered  into in  connection  with the
Company's and  Consultant's  execution of that certain  Contribution  Agreement,
dated  September  1, 1999,  between  and among the  Company,  Consultant,  Prime
Medical Services, Inc., a Delaware corporation, Prime Medical Operating, Inc., a
Delaware  corporation  ("Prime"),  Prime/BDEC  Acquisition,  L.L.C.,  a Delaware
limited  liability  company,  Barnet  Dulaney Eye Center,  P.L.L.C.,  an Arizona
professional  limited  liability  company,  LASIK Investors,  L.L.C., a Delaware
limited liability company,  David D. Dulaney,  M.D., Ronald W. Barnet,  M.D. and
Mark  Rosenberg  (the  "Contribution  Agreement").  Accordingly,  the  terms and
provisions of this Agreement shall be construed  consistently with the terms and
provisions  of the  Contribution  Agreement.  Consultant  acknowledges  that its
execution of this Agreement serves as a material inducement to the Company's and
Prime's execution of the Contribution Agreement.

     2. TERM.  The term of this  Agreement  shall commence on the Effective Date
and continue through the earlier to occur of the following:

a.   Delivery of written  notice from either Prime or the Company  following any
     breach of, or failure to perform for any reason  under,  this  Agreement by
     Consultant;

b.       The death or disability of Consultant (For purposes of this Agreement,
         the  meaning of  "disability"  shall be as  defined  in the  Disability
         Insurance Policy that covers Consultant at the time in question,  or if
         no such policy is then in force,  the  insurance  policy  that  covered
         Consultant on September 1, 1999); and

c.   The  termination  of the  exclusivity  obligations  of the  parties  to the
     Contribution  Agreement  as set forth in ARTICLE  VIII of the  Contribution
     Agreement, pursuant to the terms of the Contribution Agreement.

         3. SERVICES. During the term of this Agreement,  Consultant shall, from
time to time, make himself  available to Prime,  the Company,  and the Company's
subsidiaries  to  represent  the  interests  of such  entities  in  professional
associations and other  professional or trade  associations or groups related to
the field of refractive surgery. Furthermore, Consultant shall make himself, and
those clinics operated, utilized or controlled by Consultant, available to Prime
and the Company for  professional  development  and training of  physicians  and
other medical  professions  and staff,  all with respect to refractive  surgery.
Consultant shall make himself available to consult with other doctors affiliated
with the Company, or with whom the Company seeks an affiliation, and will assist
the Company and the Company's subsidiaries with staffing, training, consultation
on outcomes analysis and strategic planning.

                  It is  expressly  agreed  that  Consultant  is an  independent
contractor  and shall not be  construed  to be an employee  of the Company  with
regard to any matter,  under any  circumstances or for any purposes  whatsoever.
The services to be provided by Consultant hereunder are vitally important to the
Company and its  subsidiaries  and shall be rendered at such times and places as
mutually  agreed  upon  by  the  Company  and  Consultant;  provided  it is  the
understanding and agreement of all parties hereto that the  responsibilities  of
Consultant hereunder will require  substantially less than the full time efforts
of  Consultant.  Any failure or inability of  Consultant to provide the services
contemplated  in this  Agreement,  for any or no  reason,  shall  terminate  the
exclusivity  obligations of Prime arising under ARTICLE VIII of the Contribution
Agreement.

         4.  COMPENSATION.  Consultant  acknowledges and agrees that Consultants
entering into and performing its obligations  hereunder is in consideration  for
Prime and the Company  agreeing to enter into the  Consulting  Agreement and the
transactions contemplated therein.  Accordingly,  the parties hereto acknowledge
and agree that no further compensation is due Consultant for consulting services
hereunder.  The Company shall reimburse Consultant for reasonable  out-of-pocket
travel,  lodging and meal  expenses  approved by the Company and Prime and which
are necessary for Consultant to perform  consulting  services hereunder that are
requested by the Company or Prime.

         5.  AUTHORITY.  This Agreement does not grant  Consultant any authority
whatsoever  as  an  agent,   officer,   member,   employee,   manager  or  other
representative  of the  Company,  to bind or  commit  the  Company  in any  way,
contractually  or otherwise.  Except as specifically set forth in Section 4, the
Company shall have no  responsibility to reimburse the Consultant for any costs,
expenses or other amounts that may be incurred by Consultant in connection  with
the providing of Consultant's services hereunder.

     6.  CONFIDENTIAL  INFORMATION.  Consultant  shall  maintain and protect the
confidentiality  of  the  terms  and  existence  of  this  Agreement,   and  any
information obtained by Consultant pursuant to this Agreement or the performance
of this Agreement.

         7. NOTICES. Any notice required or allowed hereunder shall be deemed to
have been delivered when either hand-delivered to the party or when deposited in
the United States mail, postage pre-paid,  certified,  return receipt requested,
addressed to the party at the address set forth below or to the last new address
provided in writing by the party:

Consultant:                           ____________________________
                                      4800 North 22nd Street
                                      Phoenix, AZ  85016

Company:                              1301 Capital of Texas Highway, Suite C-300
                                      Austin, TX  78746
                                      Attn: President

     8. COMPLIANCE WITH LAWS. Consultant shall comply with all applicable state,
federal, and local laws, in the performance of its services.

     9.  ASSIGNMENT.  This  Agreement is personal to  Consultant  and may not be
assigned in whole or in part by Consultant  without the express  written consent
of the Company in each instance.  This  Agreement  shall inure to the benefit of
and be binding upon any successors and permitted assigns of the parties.

         10. WAIVER OR MODIFICATION.  The failure of any party to insist, in any
one or more instances,  upon the performance of any of the terms,  covenants, or
conditions of this contract or to exercise any right,  shall not be construed as
a  waiver  or  relinquishment  of the  future  performance  of any  such  terms,
covenants  or  conditions  or the future  exercise of such  rights.  Any waiver,
alteration,  or  modification  of any of the  provisions  of this  Agreement  or
cancellation  or replacement of this Agreement shall not be valid unless made in
writing and signed by all the parties hereto. Waiver by any party of a breach of
any provision of this Agreement shall not operate or be construed as a waiver of
any subsequent breach.

     11. CONSTRUCTION. This Agreement shall be governed by the laws of the state
of Texas.

     12.  COUNTERPARTS.  This  Agreement  may  be  executed  in  any  number  of
counterparts,  each of which shall be construed as an original for all purposes,
but all of which taken together shall constitute one and the same Agreement.

     13. DESCRIPTIVE HEADINGS. The descriptive headings for the sections in this
Agreement are inserted for  convenience  only and do not constitute  part of the
Agreement.

         14. NEGOTIATED  AGREEMENT.  This Agreement reflects the negotiations of
all parties hereto.  The language used herein shall be deemed to be the language
chosen by the  parties to express  their  mutual  intent,  and no rule of strict
construction shall be applied.  All parties  acknowledge and agree that they are
fully aware of the affiliated relationship between and among each other.

         15. SEVERABILITY.  Whenever possible,  each provision of this Agreement
will be interpreted in such manner as to be effective and valid under applicable
law, but if any  provision  of this  Agreement  is held to be  prohibited  by or
invalid under  applicable  law, such provision  will be ineffective  only to the
extent of such prohibition or invalidity,  without invalidating the remainder of
this Agreement.

         16. ENTIRE  AGREEMENT.  This Agreement,  together with the Contribution
Agreement and each other  Transaction  Document (as defined in the  Contribution
Agreement), constitutes the entire agreement between the parties with respect to
the  subject  matter  hereof,   and  all  prior   agreements,   representations,
statements, negotiations, and undertakings are superseded by this Agreement. The
binding  arbitration  provisions of the contribution  Agreement shall apply with
respect to any disputes hereunder.

                            [Signature page follows]


<PAGE>


                                SIGNATURE PAGE TO

                              CONSULTING AGREEMENT

         IN WITNESS WHEREOF,  the parties have executed this Agreement as of the
day and year first above written.

COMPANY:                     Prime/BDR Acquisition, L.L.C.



                          By:

                             Printed Name:
                             Title:

CONSULTANT:

                             Printed Name:  _____________________________



<PAGE>
                                 FIRST AMENDMENT

                                       TO

                             CONTRIBUTION AGREEMENT

     This First  Amendment  to  Contribution  Agreement  (this  "Amendment")  is
executed to be effective as of January 31, 2000,  by and between  Prime  Medical
Operating,  Inc., a Delaware corporation ("Prime"), Prime Medical Services, Inc.
a Delaware corporation ("PMSI"), Barnet Dulaney Eye Center, P.L.L.C., an Arizona
professional  limited liability company  ("BDEC"),  Prime Refractive,  L.L.C., a
Delaware  limited  liability  company  ("Prime  Refractive"),  Prime  Refractive
Management,  L.L.C., a Delaware limited liability company ("Prime  Management"),
LASIK Investors,  L.L.C., a Delaware limited liability company ("LASIK"),  David
D. Dulaney, M.D. ("Dulaney"),  Ronald W. Barnet, M.D. ("Barnet"), Mark Rosenberg
("Rosenberg"),  Prime/BDR  Acquisition,  L.L.C.,  a Delaware  limited  liability
company  ("Newco I") and  Prime/BDEC  Acquisition,  L.L.C.,  a Delaware  limited
liability  company  ("Newco II"). All of the foregoing  parties other than Prime
Refractive and Prime Management are sometimes referred to collectively herein as
the "Original Parties." Unless otherwise defined herein,  capitalized terms used
herein  shall have the meanings  ascribed to them in that  certain  Contribution
Agreement,  dated effective as of September 1, 1999,  among the Original Parties
(the "Contribution Agreement").

                             Preliminary Statements

         Prime has agreed in Section 4.3 of the  Contribution  Agreement to make
certain credit  accommodations  available to Newco I for the acquisition  and/or
development of Target Centers,  including,  without limitation,  the Development
Facility provided for in the Loan Agreement.

         Pursuant  to  the  provisions  of  Section  4.3  of  the   Contribution
Agreement,  Prime and Newco I executed that certain Loan Agreement,  dated as of
September  1,  1999  (the  "Original  Loan  Agreement")  which  provides  for  a
$40,000,000 development loan facility (the "Original Development Facility").

         Newco I has borrowed  certain amounts under the Original Loan Agreement
in order to finance the acquisition of an equity  ownership  interest in Horizon
Vision Center, Inc., a Nevada corporation.

         The Original  Parties  have agreed in ARTICLE VIII of the  Contribution
Agreement to certain exclusivity obligations and related terms and conditions.

         The  Original  Parties  have  agreed to hereby  amend the  Contribution
Agreement  to  provide  for:  (a) the  addition  of Prime  Refractive  and Prime
Management as parties to the  Contribution  Agreement,  for only those  purposes
expressly stated in this Amendment; (b) the execution of a second Loan Agreement
which shall  create a  replacement  loan  facility  that  replaces any and every
obligation of Prime to advance  additional money to any party under the Original
Loan  Agreement in respect of the  Original  Development  Facility;  and (c) the
extension of certain  provisions of the  Contribution  Agreement to specifically
apply to, benefit,  and/or bind Prime  Refractive  and/or Prime  Management,  as
applicable.

                             Statement of Agreement

         NOW,  THEREFORE,  in consideration of the premises and mutual covenants
contained  herein and for other good,  valuable and binding  consideration,  the
receipt and  sufficiency of which are hereby  acknowledged,  the parties hereto,
intending to be legally bound hereby, agree as follows:

         Section 1. Joinder of Prime  Refractive and Prime  Management.  Each of
Prime Refractive and Prime  Management  hereby agrees that its execution of this
Amendment constitutes its execution of the Contribution Agreement (as amended by
this  Amendment),  and  that  it is  hereby  made a  party  to the  Contribution
Agreement and is bound by and shall benefit from all of the applicable terms and
conditions of the Contribution Agreement (as amended by this Amendment).

         Section 2.        Amendments, Additions and Deletions to Agreement.
                           ------------------------------------------------

                    a. The Original Parties hereby agree to amend Section 4.3(a)
               of the Contribution Agreement to read in its entirety as follows:

                         " (a) Working Capital Line of Credit.  Prime Refractive
                    Management,  L.L.C.,  a Delaware limited  liability  company
                    ("Prime  Management"),   and  Prime  Refractive,  L.L.C.,  a
                    Delaware  limited  liability  company ("Prime  Refractive"),
                    have each executed a loan agreement,  dated January 31, 2000
                    (the "Development Facility") which provides for, among other
                    credit  accommodations  described below, a revolving line of
                    credit  in the  maximum  principal  amount of  $200,000  and
                    maturing  one (1)  year  after  the  Closing  (the  "Working
                    Capital Line"),  pursuant to which Prime Refractive shall be
                    entitled,   subject  to  the  conditions   and   limitations
                    contained  in the  Loan  Agreement,  to  borrow,  repay  and
                    reborrow  funds  in  order  to  meet  obligations  of  Prime
                    Refractive arising in the ordinary course of business."

     b.  The  Original  Parties  hereby  agree to amend  Section  4.3(b)  of the
Contribution Agreement to read in its entirety as follows:

                  " (b) Development Credit Facility.  In addition to the Working
                  Capital  Line,  the  Development   Facility  provides  for  an
                  additional   lending   facility,   in  the  aggregate  maximum
                  principal  amount  of  $29,165,000,  pursuant  to which  Prime
                  Refractive  shall be entitled,  subject to the  conditions and
                  limitations  contained in the Development  Facility, to borrow
                  funds,  from  time to  time,  in order  to  finance  up to one
                  hundred  percent (100%) of the purchase price (or  development
                  costs)  of a Target  Center  (as  hereinafter  defined)  being
                  acquired  (or  developed)  by  Prime   Refractive;   provided,
                  however,  that in no event shall the  Development  Facility be
                  used in instances where Prime, PMSI or one of their affiliates
                  independently   acquires  or  develops  a  Target   Center  as
                  permitted by Section 8.1. In connection  with the  Development
                  Facility,  Prime Refractive agrees to execute, and all parties
                  hereto agree to vote their interests in Prime  Refractive,  if
                  any,  and to take such other  action as may be  necessary,  to
                  cause any entity  through which Prime  Refractive  acquires or
                  develops a Target Center to execute, on or before each closing
                  date of a Target Center  acquisition  or the  commencement  of
                  development,   an   Assignment   and  Security   Agreement  in
                  substantially  the form  attached  hereto as  Exhibit G1 and a
                  Promissory Note in  substantially  the form attached hereto as
                  Exhibit G2. In  addition,  if Prime  Refractive  is to obtain,
                  through development or acquisition,  directly or indirectly, a
                  one hundred  percent  (100%)  interest in such Target  Center,
                  Prime  Refractive  and all  parties  hereto  shall  cause such
                  Target Center to execute a security  agreement,  acceptable in
                  form and substance to Prime,  granting to Prime Management the
                  highest  available  priority  security  interest in all of the
                  assets of such Target Center."

     c.  The  Original  Parties  hereby  agree to amend  Section  4.3(c)  of the
Contribution Agreement to read in its entirety as follows:

                  " (c) Pursuant to the Development Facility, Prime Management's
                  obligations  to make each  extension  of credit  described  in
                  subsection (b) above are subject  entirely and in all respects
                  to Prime and Prime Management obtaining prior written approval
                  from the lenders  under (but only if such approval is required
                  under)   either  (i)  that  certain  Loan   Agreement   for  a
                  $14,000,000 advancing term loan (the "$14,000,000  Facility"),
                  entered into by Prime  Management,  Bank of America,  N.A., as
                  administrative agent, BankBoston, N.A., as documentation agent
                  and such  lenders  named  therein  or (ii) that  certain  Loan
                  Agreement  for  a  $86,000,000   revolving  credit  loan  (the
                  "$86,000,000  Facility"),   entered  into  by  PMSI,  Bank  of
                  America, N.A., as administrative agent,  BankBoston,  N.A., as
                  documentation  agent and such lenders named  therein.  Each of
                  the parties to this Agreement acknowledges and agrees that the
                  assignment and security  agreements,  and security agreements,
                  executed  pursuant  to this  Section  and  Section 8.2 will be
                  assignable to the lenders under the $14,000,000 Facility,  and
                  that  Prime  and/or  Prime   Management   intends  to  make  a
                  collateral  assignment  for the  benefit of such  lenders.  In
                  addition, each of the parties to this Agreement agrees to take
                  such action  (including  voting their interests in any entity)
                  which may be necessary to ensure the filing and  perfection of
                  security  interests  required  to be granted  pursuant to this
                  Section."

     d.  The  Original  Parties  hereby  agree to amend  Section  4.3(d)  of the
Contribution Agreement to read in its entirety as follows:

                  " (d) Each of the Sellers acknowledges and agrees that none of
                  Prime Management,  Prime, PMSI or any affiliate of any of them
                  may be required to (i) except as  expressly  set forth in this
                  ARTICLE IV and in Section  8.2(b)(ii),  extend any  financing,
                  credit facilities,  guarantees or other credit enhancements to
                  any  Seller,  Prime  Refractive,  Newco I or  Newco II or (ii)
                  issue any of its ownership interests (or rights to acquire its
                  ownership  interests) in connection  with the acquisition of a
                  Target  Center  (provided,  however,  that  Prime  Management,
                  Prime,  PMSI or such  affiliate may elect,  upon obtaining the
                  consent  of  BDEC,  to  issue  its   ownership   interests  in
                  connection  with the  acquisition  of a Target Center by Prime
                  Refractive or any of its  subsidiaries,  and any such issuance
                  shall  be  treated  for  all  purposes  as  a  loan  by  Prime
                  Management  to Prime  Refractive  pursuant to the  Development
                  Credit  Facility,  in an amount equal to the fair market value
                  of the capital stock issued on the date of issuance)."

     e.  The  Original  Parties  hereby  agree to amend  Section  4.3(e)  of the
Contribution Agreement to read in its entirety as follows:

                  " (e)  Each of the  Sellers,  Newco I,  and  Prime  Refractive
                  acknowledges  and  agrees  that  neither  Newco  I  nor  Prime
                  Refractive  shall  distribute (or allow to be  distributed) to
                  its  members,  with  respect  to their  respective  membership
                  interests,  any  of its or its  subsidiaries'  cash  or  other
                  property  if, at the time of the  proposed  distribution,  any
                  amounts (whether  principal or interest) are outstanding under
                  the Credit  Documents or the Target Center  Lending  Documents
                  (as such terms are hereinafter defined).  Furthermore, each of
                  the Sellers, Newco I, and Prime Refractive agrees that each of
                  Newco I and Prime Refractive shall pay all available cash flow
                  in payment of its respective outstanding obligations,  if any,
                  under  the  Loan   Agreement  or   Development   Facility  (as
                  applicable),  irrespective of whether such payments exceed the
                  minimum   required   payments  under  the  Loan  Agreement  or
                  Development Facility. For purposes of allocating such payments
                  by either Newco I or Prime Refractive among any two or more of
                  such  entity's  respective   outstanding   obligations,   such
                  payments   shall  be  allocated  pro  rata,   based  upon  the
                  respective balances of such obligations,  unless (i) a greater
                  portion of the  payment is  required to be paid toward a given
                  obligation  in order to prevent a default with respect to that
                  obligation (but only to the extent necessary to prevent such a
                  default) or (ii) eighty  percent (80%) of the managers of such
                  entity elect to allocate the payments in a different manner.

                                    Notwithstanding  the  foregoing,  as long as
                  there has been no default by any Seller  under this  Agreement
                  or any other Transaction  Document  (excluding,  however,  the
                  Credit  Documents  and the Target Center  Lending  Documents),
                  then,  to the extent that (but only to the extent that) either
                  of  Newco  I or  Prime  Refractive  possesses  the  cash  flow
                  necessary (in the  reasonable  discretion of a majority of its
                  managers)  to  pay  its  liabilities  in the  ordinary  course
                  consistent  with past  practices,  such entity  agrees to make
                  quarterly  estimates of its taxable income for the current tax
                  year and, if not prohibited by law, distribute  quarterly (the
                  "Quarterly  Distributions")  an amount  that  would  cover the
                  federal  and state  income  taxes  required  to be paid by its
                  members  with respect to such  taxable  income,  based on each
                  member's then current  proportionate  interest in such entity,
                  assuming  that all members pay income  taxes on such  entity's
                  taxable  earnings  at a rate  equal to the  highest  effective
                  individual  tax rate in effect from time to time (the "Assumed
                  Tax  Rate");   provided,   further,  that  such  entity  shall
                  determine its actual taxable income at the end of each taxable
                  year and (A) if the  Quarterly  Distributions  in a given year
                  should have been higher based on the amount of actual  taxable
                  income  for  that  year,   promptly   distribute  the  amounts
                  necessary to eliminate such deficiency or (B) if the Quarterly
                  Distributions  in a given year should have been lower based on
                  the amount of actual  taxable  income for that year,  withhold
                  dollar  for  dollar   from  the  first   following   Quarterly
                  Distribution,    and   then   against   subsequent   Quarterly
                  Distributions  in a like  manner,  the  amounts  necessary  to
                  eliminate such surplus."

     f.  The  Original  Parties  hereby  agree to amend  Section  4.3(f)  of the
Contribution Agreement to read in its entirety as follows:

                  " (f) The parties  acknowledge  the execution and existence of
                  that certain Loan Agreement in the maximum principal amount of
                  $10,835,000,  dated September 1, 1999, between Prime and Newco
                  I (the "Loan Agreement"), that certain Promissory Note, in the
                  amount of $10,835,000, executed by Newco I and dated September
                  1, 1999 (the "Horizon Note"),  and that certain Assignment and
                  Security Agreement, dated September 1, 1999, between Prime and
                  Newco I (the "Horizon Security Agreement").  The parties agree
                  that the Loan  Agreement,  the  Horizon  Note and the  Horizon
                  Security Agreement are "Transaction Documents" for purposes of
                  this  Agreement.  The  Parties  further  agree  that  the Loan
                  Agreement,  the Horizon Note, the Horizon Security  Agreement,
                  and all of the loan agreements,  promissory notes, guarantees,
                  security  agreements,  assignment and security  agreements and
                  other  agreements,  documents or  instruments  executed by any
                  party in connection with the Loan Agreement or the Development
                  Facility  are  hereinafter  collectively  referred  to as  the
                  "Credit Documents"."

     g.  The  Original  Parties  hereby  agree  to  amend  Section  4.4  of  the
Contribution Agreement to read in its entirety as follows:

                  " 4.4 Capital  Contributions.  The parties agree that no party
                  shall,  except for the express  provisions  of Section 1.1 and
                  Section  4.3  of  this  Agreement  or  of  the  Organizational
                  Documents,  be required to make any capital  contribution,  or
                  extend  any  credit   facility  or  loans,   to  either  Prime
                  Refractive,  Newco I or Newco II (or a  subsidiary  of either)
                  following  the Closing,  including,  without  limitation,  for
                  purposes of providing working capital; provided, however, that
                  this sentence shall not affect any party's  obligations  under
                  Article VI with  respect to any breach of the  representations
                  or warranties made by that party under this Agreement."

                  h. The Original  Parties  hereby agree to amend Section 4.6 of
the Contribution  Agreement to replace every reference to "Newco I" contained in
Section 4.6 with a reference instead to "Prime Refractive".

     i.  The  Original  Parties  hereby  agree  to  amend  Section  4.10  of the
Contribution Agreement to read in its entirety as follows:

                   " 4.10  Guaranty  of PMSI.  PMSI hereby  unconditionally  and
                  irrevocably  guarantees  each of the payment  and  performance
                  obligations of Prime  Refractive,  Prime  Management and Prime
                  hereunder and under each of the Transaction Documents. Without
                  limiting  the  foregoing,  PMSI  agrees  that if Prime,  Prime
                  Refractive or Prime Management shall default in any obligation
                  to pay to any  Seller(s)  or Newco I any  amount  then due and
                  payable by Prime, Prime Refractive or Prime Management to such
                  Seller(s) or Newco I under ARTICLE I or ARTICLE VII hereunder,
                  PMSI shall  immediately  pay such amount to such  Seller(s) or
                  Newco I. PMSI  hereby  agrees  not to  require  any  Seller to
                  proceed against Prime Refractive,  Prime Management,  Prime or
                  any  other  person  or  to  pursue  any  other  remedy  before
                  proceeding against PMSI under this guaranty."

     j.  The  Original  Parties  hereby  agree  to  amend  Section  6.3  of  the
Contribution Agreement to read in its entirety as follows:

                   " 6.3 Security.  Without limiting or adversely  affecting the
                  rights of Prime  under  Section  9.12,  and in order to secure
                  full and  prompt  payment  of the  obligations  of each of the
                  Sellers  under  this  ARTICLE,  each of BDEC and LASIK  hereby
                  grants to Prime (for the  benefit of Prime  Refractive  or any
                  other subsidiary or affiliate of Prime to which any Seller may
                  hereafter  owe any amount) a continuing  security  interest in
                  and to distributions either of them may be entitled to receive
                  at any time after the  Closing  in  respect  of any  ownership
                  interest  held by either  of them in any of Prime  Refractive,
                  Newco I or  Newco  II.  In  connection  with  the  grant  of a
                  security interest contained in this Section,  each of BDEC and
                  LASIK  agrees  (i)  to  execute  all  documents,   agreements,
                  instruments and certificates,  and to take such other actions,
                  as are  necessary in order to fully  evidence and perfect such
                  security  interest,  and (ii) that it will not for a period of
                  five (5) years after the Closing grant or assign to any person
                  or entity, without obtaining the express prior written consent
                  of  Prime  in  each  instance,  rights  of any  nature  in the
                  distributions covered by the security interest granted in this
                  Section,  irrespective of whether such rights are to be senior
                  or  subordinate  to the rights  granted  under  this  Section;
                  provided, however, that Prime acknowledges and agrees that any
                  grant of a security interest in such distributions by LASIK to
                  either Prime  Management or the lenders under the  $14,000,000
                  Facility  shall not be a violation  of this  Section,  and the
                  grant to the lenders under the  $14,000,000  Facility shall be
                  senior to the  security  interest  hereby  granted by LASIK to
                  Prime."

                  k. The Original  Parties  hereby agree to amend the  following
subsections  of Section  8.1 of the  Contribution  Agreement  to  replace  every
reference to "Newco I" contained in such subsections with a reference instead to
"Prime  Refractive":  introductory  paragraph  to Section 8.1;  Section  8.1(b);
Section 8.1(c); and Section 8.1(d).

     l.  The  Original  Parties  hereby  agree to amend  Section  8.1(e)  of the
Contribution Agreement to read in its entirety as follows:

                   " (e) The  acquisition  or  development of such Target Center
                  was  initiated,  arranged  for,  originated or financed by any
                  entity  affiliated  with PMSI  (other  than Prime  Refractive,
                  Newco I or Newco II, or any future  subsidiaries  of either of
                  them)  which has  previously  acquired  or  developed a Target
                  Center,  or an  interest  therein,  pursuant  to  any  of  the
                  exceptions to exclusivity contained in subsections (a) through
                  (g) of this Section;"

     m. The  Original  Parties  hereby  agree to amend  the first  paragraph  of
Section 8.2(g) of the Contribution Agreement to read in its entirety as follows:

                   " (g) Notwithstanding the exclusivity obligation contained in
                  Section  8.1,  LASIK  and/or  one or more of their  affiliates
                  shall be  entitled  to  independently  acquire or develop  any
                  Target Center to which any one or more of the following apply:
                  (i) a  majority  of the  board of  directors  of  Prime  votes
                  against the  acquisition of such Target Center;  or (ii) Prime
                  Refractive is unable to finance the acquisition of such Target
                  Center using the Development  Facility,  solely because of the
                  limitation  set forth in Section  4.3(c);  provided,  however,
                  that:"

                  n. The Original  Parties  hereby agree to amend Section 9.3 of
the Contribution  Agreement to replace every reference to "Newco I" contained in
Section 9.3 with a reference instead to "Prime Refractive, Newco I".

     o.  The  Original  Parties  hereby  agree  to  amend  Section  9.4  of  the
Contribution Agreement to read in its entirety as follows:

                   " 9.4 Non-Competition  Agreement.  Each of PMSI, Prime, Prime
                  Management  and each Seller,  as a material  inducement to one
                  another to enter into this  Agreement,  hereby agrees that, at
                  all times  during  which the  provisions  of Article  VIII are
                  applicable, and at all times until five (5) years after either
                  LASIK  and its  affiliates  (excluding  PMSI,  Prime,  and the
                  subsidiaries  of either of them),  or Prime and its affiliates
                  (excluding  LASIK), no longer own any equity or other interest
                  in either  Newco I or Prime  Refractive,  such  party will not
                  directly or  indirectly,  either through any kind of ownership
                  (other  than  ownership  of  securities  of  a  publicly  held
                  corporation  of which it owns less than five  percent  (5%) of
                  any  class  of  outstanding  securities),  or as a  principal,
                  shareholder, agent, employer, advisor, consultant,  co-partner
                  or in any  individual  or  representative  capacity  whatever,
                  either  for its own  benefit  or for the  benefit of any other
                  person, corporation or other entity, without the prior written
                  consent  of  each  other  party  hereto,  commit  any  of  the
                  following acts,  which acts shall be considered  violations of
                  this covenant not to compete:

                                    (a)   Except    through   Newco   I,   Prime
                  Refractive,   either  of  their  subsidiaries,  or  Newco  II,
                  directly or indirectly engage in, or provide,  anywhere within
                  a fifty  (50) mile  radius  of any  center  or  facility  that
                  provides   Refractive  Surgery  and  is  owned,   directly  or
                  indirectly, partially or wholly, by Newco I, Prime Refractive,
                  or  a  subsidiary  of  either  of  them   (collectively,   the
                  "Restricted Area"), any services (other than services included
                  in the practice of medicine)  related to (i) the  operating of
                  centers or facilities that provide  Refractive  Surgery,  (ii)
                  the manufacture,  maintenance,  refurbishing, repair, sale, or
                  leasing  of any  equipment  related  to or  necessary  for the
                  operating of centers or  facilities  that  provide  Refractive
                  Surgery, or (iii) providing any management services,  training
                  or  consulting  services  related  to any  of  the  activities
                  described in (i) or (ii);

                                    (b)   Except    through   Newco   I,   Prime
                  Refractive,  the  subsidiaries of either of them, or Newco II,
                  directly or indirectly provide, anywhere within the Restricted
                  Area, (i) facilities,  equipment and  non-physician  personnel
                  for the performance by physicians of Refractive Surgery,  (ii)
                  the marketing, scheduling and management of Refractive Surgery
                  (but  excluding,  with  respect to either  Barnet or  Dulaney,
                  marketing, scheduling and management of patients for treatment
                  by Barnet or Dulaney,  respectively),  (iii) the credentialing
                  and scheduling of physicians to perform Refractive Surgery and
                  (iv) the billing,  collecting or accounting for the use of any
                  such facilities, equipment or non-physician personnel;

                                    (c) Directly or indirectly request or advise
                  any  person,  firm,  physician,  corporation  or other  entity
                  having a business relationship with Newco I, Prime Refractive,
                  a  subsidiary  of either of them,  Prime,  each  Seller or any
                  affiliate  or  related  entity  of any of them,  to  withdraw,
                  curtail, or cancel its business with such person or entity; or

                                    (d) Directly or indirectly hire any employee
                  of Newco I, Prime Refractive,  any subsidiary of either of the
                  foregoing,  Prime,  any  Seller or any  affiliate  or  related
                  entity of any of them,  or induce or attempt to influence  any
                  employee  of Newco I,  Prime  Refractive,  any  subsidiary  of
                  either  of the  foregoing,  Prime,  any  Seller  or  any  such
                  affiliate or related entity to terminate his or her employment
                  with such person or entity."

               p. The Original  Parties hereby agree to amend Section 9.5 of the
          Contribution Agreement to read in its entirety as follows:

                   " 9.5  Exclusivity.  Each of the parties hereto  acknowledges
                  and agrees that any  acquisition  or  development  of a Target
                  Center by Prime Management,  Prime, PMSI, Newco II or a Seller
                  through an entity not owned (wholly or partially,  directly or
                  indirectly) by Prime Refractive or Newco I shall be subject to
                  the  provisions  of Section  9.4,  regardless  of whether such
                  acquisition or development is  contemplated by or provided for
                  in the provisions of ARTICLE VIII."

               q. The Original  Parties hereby agree to amend Section 9.8 of the
          Contribution Agreement to read in its entirety as follows:

               " 9.8 Special Options to Sell or Acquire Interests In Newco I and
          Prime Refractive.


                                    (a) Option to Sell.  Upon the  expiration of
                  five (5) years  immediately  following the Closing Date, if no
                  Seller is in breach of this Agreement or any other Transaction
                  Document,  all or any of the  Sellers  shall at any time,  and
                  from time to time, be entitled to require that Prime  purchase
                  from such  Seller(s)  up to a  maximum  twenty  percent  (20%)
                  interest  in  each  of  Newco  I and  Prime  Refractive  (when
                  aggregated  for each  entity with all other  purchases  by all
                  Sellers  pursuant  to  this  Section),   upon  the  terms  and
                  conditions  hereinafter set forth, by giving written notice of
                  such election to Prime;  provided,  however, that any exercise
                  of the option to sell  pursuant to this  Section  must (unless
                  Prime  consents  otherwise  in writing) be made by such Seller
                  with respect to exactly equal percentage  interests in Newco I
                  and Prime Refractive,  in each instance and taken individually
                  and not in combination with elections by another Seller.

                                    (b)  No  Further  Obligation.   The  Sellers
                  acknowledge  and agree that Prime shall be under no obligation
                  to notify any  Seller of the  exercise  by  another  Seller of
                  rights under this Section,  and that Prime may not,  under any
                  circumstances,  be required to purchase more than an aggregate
                  twenty  percent  (20%)  interest  in  either  Newco I or Prime
                  Refractive  (considering all purchases by all Sellers pursuant
                  to this Section), regardless of whether one Seller disposes of
                  more or less of an  interest  in Newco I and Prime  Refractive
                  under this Section than another Seller.

                         (c) Purchase Price. The purchase price for any interest
                    transferred  pursuant to this Section shall,  in the absence
                    of an agreement on price  between  Prime and the  applicable
                    Seller(s), be determined as follows:

                                            (i) If the  exercise  of the  option
                           hereunder is after the expiration of such ninety (90)
                           day period,  then the purchase price must be mutually
                           agreed upon by the applicable Seller(s) and Prime.

                                            (ii) If the  exercise  of the option
                           hereunder  is  within  the  ninety  (90)  day  period
                           immediately  following the expiration of the five (5)
                           year period  described in Section 9.8(a),  then Prime
                           shall select a certified  business appraiser (that is
                           a member of either the American Society of Appraisers
                           or the Institute of Business Appraisers) to value the
                           interests being transferred. If the selling Seller(s)
                           under  this  Section  do not  agree  with  the  value
                           determined by Prime's appraiser,  such Seller(s) may,
                           at their own expense,  select a second appraiser that
                           is a  member  of  one or  both  of  the  above  named
                           professional  organizations  to value  the  interests
                           being transferred. If the two appraisers cannot agree
                           on the value of the interests being transferred,  the
                           two  appraisers   shall   mutually   select  a  third
                           appraiser (that meets the above described  membership
                           requirements)    to   value   the   interests   being
                           transferred  together with the first two  appraisers,
                           based on a majority vote. Any valuation determined by
                           such  majority  vote  shall  be  final,  binding  and
                           conclusive. The expense of such third appraiser shall
                           be  paid  by  the  selling   Seller(s),   unless  the
                           appraised  value  ultimately  determined is more than
                           ten percent (10%)  greater than the value  determined
                           by Prime's original  appraiser,  in which event Prime
                           shall bear the entire cost of the third appraiser. If
                           the  exercise  of the option  hereunder  is after the
                           expiration  of such ninety (90) day period,  then the
                           purchase  price must be  mutually  agreed upon by the
                           applicable Seller(s) and Prime.

                                    (d)  Such  purchase  price  shall be paid in
                  immediately  available  funds at the  closing of the  transfer
                  pursuant to this Section. The closing of any purchase and sale
                  pursuant  to this  Section  shall take place at the  principal
                  office of Prime or such other  place  designated  by Prime and
                  the  applicable  Seller(s),  on the  thirtieth day (or if such
                  thirtieth  day is not a business  day,  the next  business day
                  following the thirtieth day) following the final determination
                  of a  purchase  price  under  subsection  (c)  above.  At such
                  closing,  Seller  shall  execute all  documents  and take such
                  other  actions as may be  reasonably  necessary  to deliver to
                  Prime title to the  interests  transferred,  free and clear of
                  all liens, claims, encumbrances or restrictions of any kind or
                  nature  whatsoever,   except  (i)  those  established  in  the
                  organizational  documents  and other  governing  documents  of
                  Newco I and  Prime  Refractive,  (ii)  those  in  favor of the
                  lenders  under   $14,000,000   Facility  and  the  $86,000,000
                  Facility pursuant to any Transaction  Document and (iii) those
                  in  favor of Prime or any  affiliate  or  subsidiary  of Prime
                  pursuant to any Transaction Document.

                                    (e)    Exceptions.    Notwithstanding    the
                  foregoing  provisions of this Section 9.8,  Prime shall not be
                  obligated  to purchase any interest in either Newco I or Prime
                  Refractive  pursuant  to this  Section  if Prime is  unable to
                  obtain  financing  for such  purchase  from a third party upon
                  reasonable  market terms,  after Prime and PMSI have exercised
                  commercially reasonable efforts to obtain such financing."

                  r. The Original  Parties hereby agree to amend Section 9.12 of
the Contribution  Agreement to replace every reference to "Newco I" contained in
Section  9.12 with a reference  instead to "Prime  Refractive,  Newco I", and to
replace  every  reference  to "Prime or PMSI"  contained  in Section 9.12 with a
reference instead to "Prime Management, Prime or PMSI".

     s. The  Original  Parties  hereby  agree to amend  the first  paragraph  of
Exhibit G3 to the Contribution Agreement to read in its entirety as follows:

                   " THIS ASSIGNMENT AND SECURITY  AGREEMENT (this  "Agreement")
                  is made and  entered  into as of the  ____ day of  __________,
                  200__, by and between Prime Refractive  Management,  L.L.C., a
                  Delaware limited  liability  company (the "Secured Party") and
                  Prime Refractive, L.L.C., a Delaware limited liability company
                  (the "Debtor")."

     t. The Original  Parties  hereby agree to amend Recital A. of Exhibit G3 to
the Contribution Agreement to read in its entirety as follows:

                    " A. Debtor and Secured  Party have  executed and  delivered
               that certain Contribution  Agreement dated effective September 1,
               1999,  between and among  Debtor,  Secured  Party,  Prime Medical
               Operating, Inc., a Delaware corporation,  Prime Medical Services,
               Inc., a Delaware corporation,  Prime/BDEC Acquisition,  L.L.C., a
               Delaware  limited  liability  company,   Prime/BDR   Acquisition,
               L.L.C., a Delaware limited liability company,  Barnet Dulaney Eye
               Center,  P.L.L.C.,  an  Arizona  professional  limited  liability
               company,  LASIK Investors  L.L.C., a Delaware  limited  liability
               company, David D. Dulaney, M.D., Ronald W. Barnet, M.D., and Mark
               Rosenberg  (as  amended  by  that  certain  First   Amendment  to
               Contribution  Agreement  dated as of January 31, 2000,  among the
               foregoing  parties,  the  "Contribution  Agreement"),   and  that
               certain Loan  Agreement,  dated as of January 31, 2000 (the "Loan
               Agreement"),  pursuant  to which  Secured  Party  agrees  to make
               certain  loans  to  Debtor  on  the  terms  and  subject  to  the
               conditions provided therein."

                  u. The Original  Parties  hereby  agree to amend  Article I of
Exhibit G3 to the Contribution Agreement to add the following Section 1.3 in its
entirety as a new Section:

                    1.3  Subordination.  Liens created hereby are subordinate to
               liens in favor  of  Lenders  (as  such  term is  defined  in that
               certain Loan  Agreement  for a $14,000,000  advancing  term loan,
               entered  into  by  Secured  Party,  Bank  of  America,  N.A.,  as
               administrative  agent,  BankBoston,  N.A., as documentation agent
               and such Lenders).

                  v. The Original  Parties  hereby agree to amend Section 4.3 of
Exhibit G3 to the  Contribution  Agreement to replace the  reference to "Section
1.1(c)" contained in Section 4.3 with a reference instead to "Section 1.1(d)".

                  w. The Original  Parties  hereby  agree to amend  Article V of
Exhibit G3 to the  Contribution  Agreement  to replace the  reference to "Target
Center"  contained in Article V with a reference  instead to "Target  Center (as
defined in the Contribution Agreement)".

     x. The Original  Parties hereby agree to amend Section 9.2 of Exhibit G3 to
the Contribution  Agreement to replace the reference to "Prime/BDR  Acquisition,
L.L.C." contained in Section 9.2 with a reference instead to "Prime  Refractive,
L.L.C.".

     y. The Original Parties hereby agree to amend the signature page to Exhibit
G3 to the  Contribution  Agreement to (i) replace the  reference  to  "Prime/BDR
Acquisition, L.L.C." contained in the signature page with a reference instead to
"Prime  Refractive,  L.L.C.",  (ii)  replace  the  reference  to "Prime  Medical
Operating,  Inc."  contained in the signature  page with a reference  instead to
"Prime Refractive Management, L.L.C.", and (iii) replace the reference to "1999"
contained in the signature page with a reference instead to "200__".

     z. The  Original  Parties  hereby  agree to amend the second  paragraph  of
Exhibit G5 to the Contribution Agreement (beginning with "Borrower:") to replace
the reference to "Prime/BDR  Acquisition,  L.L.C."  contained in such  paragraph
with a reference instead to "Prime Refractive, L.L.C.".

          aa. The Original Parties hereby agree to amend the fourth paragraph of
     Exhibit G5 to the  Contribution  Agreement  (beginning  with  "LENDER:") to
     replace  the  reference  to "Prime  Medical  Operating,  Inc.,  a  Delaware
     corporation" contained in such paragraph with a reference instead to "Prime
     Refractive Management, L.L.C., a Delaware limited liability company".

          bb. The Original Parties hereby agree to amend the eighth paragraph of
     Exhibit G5 to the Contribution  Agreement (beginning with "payment terms:")
     to replace the  reference  to "1999"  contained  in such  paragraph  with a
     reference instead to "200__".

          cc. The Original  Parties hereby agree to amend the ninth paragraph of
     Exhibit G5 to the Contribution Agreement (beginning with "Loan Agreement:")
     to read in its entirety as follows:

                  "LOAN  AGREEMENT:  This Note is  executed  pursuant  to and is
                  governed by the terms of that certain Loan Agreement  dated as
                  of January  31,  2000,  executed by  Borrower  and Lender,  as
                  amended (collectively, the "Loan Agreement")."

                  dd.  The  Original  Parties  hereby  agree  to  amend  Section
2(a)(ii) of Exhibit G5 to the Contribution Agreement to replace the reference to
"Lender"  contained  in Section  2(a)(ii)  with a reference  instead to "Lender,
Prime Medical Operating, Inc.".

          ee. The Original Parties hereby agree to amend Section 4(c) of Exhibit
     G5 to the Contribution Agreement to read in its entirety as follows:

                         " (c) All other documents signed in connection with the
                    Loan   Agreement  or  the  loan   evidenced  by  this  Note,
                    including,  without  limitation,  that certain  Contribution
                    Agreement,  dated effective  September 1, 1999,  between and
                    among  Borrower,  Lender,  Prime Medical  Services,  Inc., a
                    Delaware  corporation,  Prime  Medical  Operating,  Inc.,  a
                    Delaware  corporation,  Prime/BDEC  Acquisition,  L.L.C.,  a
                    Delaware limited liability company,  Prime/BDR  Acquisition,
                    L.L.C., a Delaware limited liability company, Barnet Dulaney
                    Eye  Center,   P.L.L.C.,  an  Arizona  professional  limited
                    liability  company,  LASIK  Investors,  L.L.C.,  a  Delaware
                    limited liability company, David D. Dulaney, M.D., Ronald W.
                    Barnet, M.D., and Mark Rosenberg (as amended by that certain
                    First  Amendment  to  Contribution  Agreement  dated  as  of
                    January  31,  2000,   among  the  foregoing   parties,   the
                    "Contribution  Agreement") and each Transaction Document (as
                    such term is defined in the Contribution Agreement)."

     ff.  The  Original  Parties  hereby  agree to amend the  signature  page to
Exhibit G5 to the Contribution  Agreement to replace the reference to "Prime/BDR
Acquisition, L.L.C." contained in the signature page with a reference instead to
"Prime Refractive, L.L.C.".

                  gg. The Original  Parties  hereby agree to (i) delete  Exhibit
G1,  Exhibit G2 and  Exhibit G4 from the  Contribution  Agreement,  (ii)  rename
Exhibit G3 as Exhibit G1, (iii) rename  Exhibit G5 as Exhibit G2, and (iv) amend
the TABLE OF EXHIBITS of the Contribution  Agreement to replace the reference to
"Exhibits G1 to G5" contained in the TABLE OF EXHIBITS with a reference  instead
to "Exhibits G1 and G2".

         Section 3. Amendment of Loan Agreement. Each Original Party agrees that
the Original Loan Agreement is hereby amended to eliminate the $200,000  Working
Capital Line and to reduce the remaining maximum principal amount of $40,000,000
to $10,835,000.  Each Original Party further  acknowledges and agrees that Prime
has  previously  advanced the maximum  principal  amount under the Original Loan
Agreement, and that, accordingly,  Prime is hereby unconditionally released from
any  obligation  (whether  asserted now or in the future) to advance  additional
money under the Original Loan Agreement.

         Section 4. Relationship Between Prime and Prime Refractive. The parties
agree that for all  purposes  under the  Contribution  Agreement,  each of Prime
Refractive  and Prime  Management  shall be deemed an  affiliate of Prime for as
long as Prime owns, directly or indirectly, an equity ownership interest in it.

         Section  5.  Transaction  Document.  This  Amendment,  and  each  other
document, agreement, and certificate executed in connection with or contemplated
by  this  Amendment  (each  a  "Related   Document"),   shall  be  considered  a
"Transaction Document," as such term is used in the Contribution Agreement.

     Section 6. No Assumption of Liabilities.  Notwithstanding  any provision of
this  Amendment or any Related  Document,  neither  Prime  Refractive  nor Prime
Management assumes any debts,  obligations or liabilities of any of the Original
Parties.

         Section 7. Authority.  Each of Prime  Refractive,  Prime Management and
each Original Party,  hereby represents and warrants (severally and not jointly)
that it has full power and  authority to enter into and perform  this  Amendment
and each  Related  Document  to be  executed or  delivered  by such  party.  The
execution,  delivery,  and  performance  of  this  Amendment  and  such  Related
Documents have been duly  authorized by all necessary  action of such party and,
if applicable,  its respective officers and owners. This Amendment has been duly
and validly  executed and  delivered by such party and  constitutes  a valid and
binding  obligation of such party  enforceable  against such party in accordance
with its terms. The execution,  delivery,  and performance by such party of this
Amendment  and each such Related  Document does not violate or conflict with (a)
any law,  rule,  or regulation  applicable  to such party,  (b) any agreement to
which such party is a party, or (c) the organizational documents of such party.

         Section 8. Ratification by Prime  Refractive.  Each of Prime Management
and each Original Party agrees that by executing this Amendment, it is deemed to
be voting its ownership interest (if any) in Prime Refractive to authorize Prime
Refractive  to enter into and  perform  this  Amendment  and each other  Related
Document to which Prime Refractive is a party. Each such party agrees to execute
such  resolutions and written  consents,  and take such other actions,  in their
capacities  as  members  of Prime  Refractive,  as any other  such  party  shall
reasonably  require  after  the date of this  Amendment  in order to have  Prime
Refractive  ratify and adopt this Amendment,  notwithstanding  the date of Prime
Refractive's creation.

         Section 9. Cooperation  Relating to Financial  Statements.  Each of the
Sellers  agrees to  cooperate  with Prime in the  preparation  of any  financial
statements of Prime  Refractive which Prime or its affiliates may be required by
any applicable law to prepare.

         Section  10.  Effect  on  Existing   Agreements.   This   Amendment  is
incorporated  into  the  Contribution  Agreement  by  reference.  Other  than as
provided in this Amendment,  the Contribution  Agreement (including Exhibits and
Schedules)  has not been  modified  or amended  and is in full force and effect.
Each Original Party hereby  affirms that it remains a party to the  Contribution
Agreement (as amended by this Amendment)  after the execution of this Amendment.
The Contribution Agreement may be restated as amended hereby for the convenience
of the parties  hereto.  This Amendment may be executed in a number of identical
counterparts  which, taken together,  shall constitute  collectively one and the
same agreement.

                            [Signature pages follow]



<PAGE>

                                SIGNATURE PAGE TO
                                 FIRST AMENDMENT

                                       TO

                             CONTRIBUTION AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Amendment as of the day and year first above written.

PMSI:                   PRIME MEDICAL SERVICES, INC.


                        By:

                        Printed Name:
                        Title:



PRIME:                 PRIME MEDICAL OPERATING, INC.


                       By:
                       Printed Name:
                       Title:



PRIME MANAGEMENT:      PRIME REFRACTIVE MANAGEMENT, L.L.C.


                       By:
                       Printed Name:
                       Title:



BDEC:                  Barnet Dulaney Eye CENTER, P.L.L.C.


                       By:
                            David D. Dulaney, M.D., manager



LASIK:                LASIK INVESTORS, L.L.C.


                       By:
                            Ronald W. Barnet, M.D., manager

                       By:
                            David D. Dulaney, M.D., manager



NEWCO I:               PRIME/BDR ACQUISITION, L.L.C.


                       By:      LASIK Investors, L.L.C.. - Member

                       By:

                                Ronald W. Barnet, M.D., manager

                       By:

                                David D. Dulaney, M.D., manager


                       By:      Prime Medical Operating, Inc. - Member

                       By:

                                    Printed Name:

                                    Title:


NEWCO II:             PRIME/BDEC ACQUISITION, L.L.C.

                      By:      Barnet Dulaney Eye Center, P.L.L.C. - Member

                      By:

                               Ronald W. Barnet, M.D., manager

                      By:

                               David D. Dulaney, M.D., manager


                      By:      Prime Medical Operating, Inc. - Member

                      By:

                                Printed Name:
                                Title:



PRIME REFRACTIVE:          PRIME REFRACTIVE, L.L.C.

                       By:      LASIK Investors, L.L.C.. - Member

                       By:

                                Ronald W. Barnet, M.D., manager

                       By:

                                David D. Dulaney, M.D., manager


                       By:      Prime Refractive Management, L.L.C. - Member

                       By:

                                Printed Name:

                                Title:



DULANEY:

                                David D. Dulaney, M.D.

BARNET:

                                Ronald W. Barnet, M.D.

ROSENBERG:

                                Mark Rosenberg



                                                  LOAN AGREEMENT

         This Loan Agreement  (this  "Agreement") is entered into as of the 1st
day of September, 1999, by and between Prime Medical Operating, Inc., a Delaware
corporation,  and Prime/BDR  Acquisition,  L.L.C., a Delaware limited  liability
company.

                                                   Definitions:

EFFECTIVE DATE:                 September 1, 1999

     BORROWER:  Prime/BDR  Acquisition,  L.L.C.,  a Delaware  limited  liability
          company
     BORROWER'S  ADDRESS:  1301 Capital of Texas Highway,  Suite C-300,  Austin,
Texas 78746
     LENDER: Prime Medical Operating, Inc., a Delaware corporation
     LENDER'S ADDRESS: 1301 Capital of Texas Highway, Suite C-300, Austin, Texas
78746
NOTES:

     Working  Capital  Note:  Promissory  Note (Line of  Credit) in the  maximum
principal  amount of $200,000 (the "Working Capital Maximum  Principal  Amount")
dated  September  ___, 1999,  executed by Borrower,  and payable to the order of
Lender as provided therein (the "Working Capital Note").
     Development  Facility  Notes:  Promissory  Notes in the  aggregate  maximum
original principal amount not to exceed  $40,000,000 (the "Development  Facility
Maximum  Principal  Amount"),  executed by Borrower  and payable to the order of
Lender as provided therein (the "Development Facility Notes"). Collectively, the
Working Capital Notes and the Development  Facility Notes are referred to herein
as the "Notes."
     SECURITY AGREEMENTS: All documents,  agreements and instruments hereinafter
or herewith  executed by Borrower,  LASIK Investors,  L.L.C., a Delaware limited
liability  company ("LASIK") or any Target Center securing this Agreement or the
obligations under any of the Notes.
          LOAN  DOCUMENTS:   This  Agreement,  the  Working  Capital  Note,  the
     Development  Facility  Notes,  the  Security  Agreements,   and  all  other
     documents,   agreements,   and  instruments  now  or  hereafter   existing,
     evidencing,  securing,  or  otherwise  relating to this  Agreement  and any
     transactions  contemplated by this Agreement, as any of the foregoing items
     may be modified or supplemented from time to time.
INDEBTEDNESS:  All present and future indebtedness,  obligations and liabilities
of Borrower to Lender,  all present  and future  indebtedness,  obligations  and
liabilities  of any Target Center to Lender,  and all renewals,  extensions  and
modifications  of either of the foregoing,  arising  pursuant to any of the Loan
Documents  and all  interest  accruing  thereon,  and  all  other  fees,  costs,
expenses, charges and attorneys' fees payable, and covenants performable,  under
any of the Loan Documents (including without limitation this Agreement).

          DEFINED  TERMS:  Terms not  otherwise  defined  herein  shall have the
     meaning  provided in that certain  Contribution  Agreement  dated effective
     September 1, 1999, by and among Barnet Dulaney Eye Center,  P.L.L.C., David
     D. Dulaney,  M.D.,  Ronald W. Barnet,  M.D., Mark Rosenberg,  Prime Medical
     Services, Inc., Lender, Borrower, LASIK and Prime/BDEC Acquisition,  L.L.C.
     (the "Contribution  Agreement").  For the purposes hereof the terms "Target
     Centers"  and  "Target  Center"  shall  have the  meaning  set forth in the
     Contribution Agreement, but shall include, upon the acquisition of a Target
     Center  by  Borrower  or any  subsidiary  or  affiliate  of  Borrower,  the
     subsidiary or affiliate utilized to make such acquisition.
                                                    AGREEMENT:

          Borrower has requested from Lender the credit accommodations described
     below, and Lender has agreed to provide such credit  accommodations  on the
     terms and conditions  contained  herein.  Therefore,  for good and valuable
     consideration,  the receipt and  sufficiency  of which  Lender and Borrower
     acknowledge, Lender and Borrower hereby agree as follows:
                                                     ARTICLE I
                                             THE WORKING CAPITAL LOAN

          1.1 The  Working  Capital  Loan.  Lender  agrees to lend and  Borrower
     agrees to  borrow an amount  not to  exceed  the  Working  Capital  Maximum
     Principal Amount on the terms and conditions set forth herein (the "Working
     Capital  Loan").  The Working Capital Loan will be evidenced by the Working
     Capital Note. ------------------------

          1.2  Revolving  Line of Credit.  Subject to and in  reliance  upon the
     terms,  conditions,  representations and warranties  hereinafter set forth,
     Lender agrees to make advances (the "Working Capital Advances") to Borrower
     from  time to  time  during  the  period  from  the  Effective  Date to and
     including the one year  anniversary  of the Effective  Date (the  "Maturity
     Date"),  in an aggregate  amount not to exceed the Working  Capital Maximum
     Principal   Amount.   Each   Working   Capital   Advance   must  be  either
     ------------------------  $10,000 or a higher integral multiple of $10,000.
     Funds  borrowed  and repaid may be  reborrowed,  so long as all  conditions
     precedent to Working  Capital  Advances are met. The purpose of the Working
     Capital  Advances is to provide  funds to Borrower for working  capital and
     for other general business purposes of Borrower.
          1.3 Interest and Repayment.  Borrower  shall pay the aggregate  unpaid
     principal  amount of all Working  Capital  Advances in accordance  with the
     terms of the Working  Capital Note  evidencing the  indebtedness  resulting
     from  such  Working  Capital  Advances.  Interest  on the  Working  Capital
     Advances  shall be due and payable in the manner and at the times set forth
     in the Working  Capital Note,  with final  maturity of the Working  Capital
     Note being on or before the Maturity Date. ----------------------

          1.4 Making Advances. Each Working Capital Advance shall be made within
     two business  days of written  notice (or  telephonic  notice  confirmed in
     writing) given by noon (Austin,  Texas time) on a business day of Lender by
     Borrower to Lender specifying the amount and date thereof (which may be the
     same  business  day) and if sent by wired funds,  at Lender's  option,  the
     wiring  instructions  of the  deposit  account  of  Borrower  to which such
     Working Capital Advance is to be deposited. ---------------

          1.5  Payments  and  Computations.  Borrower  shall  make each  payment
     hereunder and under the Working  Capital Note on the day when due in lawful
     money of the United  States of America to Lender at  Lender's  Address  for
     Payment in same day funds.  All  repayments  of  principal  on the  Working
     Capital Note shall be in a minimum amount of $1,000,  or a higher  integral
     multiple of $1,000. All computations of interest shall be made by Lender on
     the   basis  of  the   actual   number   of  days   (including   the  first
     -------------------------  day but excluding the last day) in the year (365
     or 366,  as the  case  may be)  elapsed,  but in no  event  shall  any such
     computation  result in an amount of interest  that would cause the interest
     contracted for, charged or received by Lender to be in excess of the amount
     that would be payable at the Highest Lawful Rate, as herein defined.
                                                    ARTICLE II
                                          THE DEVELOPMENT FACILITY LOANS

          2.1 The Development Facility. Subject to the terms of the Contribution
     Agreement  and  the  terms,  conditions,   representations  and  warranties
     hereinafter  set forth,  Lender  agrees to lend Borrower from time to time,
     the amounts necessary to acquire or develop Target Centers, in an aggregate
     amount not to exceed the  Development  Facility  Maximum  Principal  Amount
     (collectively, the "Development Facility Loans"). ------------------------

         2.2 Development  Facility Loans.  Each  Development  Facility Loan will
finance  up to 100% of the  purchase  price  (or  development  cost) of a Target
Center being acquired (or developed) by Borrower.  The parties  acknowledge that
the grant of any Development Facility Loan does not create any obligation on the
part of Lender to extend further Development Facility Loans. Additionally,  each
Development  Facility Loan is subject in all respects to Lender  obtaining prior
written  approval from the bank  syndication  under its or its parent  company's
outstanding  borrowing  facilities  and  the  execution  and  delivery  of  such
guarantees by Borrower as may be required by such bank syndication.  Pursuant to
the Contribution Agreement, each Development Facility Loan must be (a) evidenced
by a separate Development Facility Note executed by Borrower, (b) secured by all
of LASIK's  ownership  interest in Borrower as  evidenced by an  Assignment  and
Security  Agreement  executed by LASIK,  and (c)  accompanied  by Assignment and
Security Agreements executed by Borrower. In addition, if Borrower is acquiring,
directly or indirectly, a one hundred percent (100%) interest in a Target Center
(hereinafter  referred to as a "100% Target Center"),  Borrower shall cause such
Target Center to execute a security agreement,  acceptable in form and substance
to  Lender,  granting  to Lender or one of  Lender's  subsidiaries  the  highest
available priority security interest in all of the assets of such Target Center.

          2.3 Interest and  Repayment.  Borrower and Target Center shall pay the
     unpaid principal amount under each Development  Facility Note in accordance
     with the terms of the respective  Development  Facility  Note.  Payments of
     interest and principal on each  Development  Facility Note shall be due and
     payable  in the  manner  and at  the  times  set  forth  in the  respective
     Development Facility Note. ----------------------

                                   ARTICLE III
      CONDITIONS TO WORKING CAPITAL ADVANCES AND DEVELOPMENT FACILITY LOANS

          3.1  Conditions  Precedent to Initial  Working  Capital  Advance.  The
     obligation of Lender to make its initial Working Capital Advance is subject
     to the condition precedent that Lender shall have received on or before the
     day of such  Working  Capital  Advance  the  following,  each  in form  and
     substance satisfactory to Lender and properly executed by Borrower or other
     appropriate  parties:  (a)  the  Working  Capital  Note  duly  executed  by
     Borrower,  and  (b)  such  other  documents,  opinions,   certificates  and
     ------------------------------------------------------- evidences as Lender
     may reasonably request.

          3.2 Conditions  Precedent to Each Working Capital  Advance/Development
     Facility Loan. In addition to the  conditions  precedent  stated  elsewhere
     herein,  Lender shall not be obligated to make any Working  Capital Advance
     or        any        Development        Facility        Loan        unless:

          (a) the  representations  and  warranties  contained in Article IV are
     true and  correct in all  material  respects  on and as of the date of such
     Working Capital Advance or Development Facility Loan, as though made on and
     as of such date with such changes therein;
          (b) on the date of the Working Capital Advance or Development Facility
     Loan,  no Event of Default,  and no event which,  with the lapse of time or
     notice or both,  could  become an Event of  Default,  has  occurred  and is
     continuing;
          (c) there shall have been no material adverse change, as determined by
     Lender in its reasonable  judgment,  in the financial condition or business
     of Borrower;
          (d) there has been no breach or  threatened  breach by Borrower  under
     the  Contribution  Agreement or any  Transaction  Document (as such term is
     defined in the Contribution Agreement);
              with respect to each Development  Facility Loan, Borrower executes
the respective Development Facility Note and Borrower executes an Assignment and
Security  Agreement  in the form  attached  as  Exhibit  G3 to the  Contribution
Agreement,  and  otherwise in form and substance  acceptable  to Lender  wherein
Lender is granted a first lien perfected  security interest in all of Borrower's
or Borrower's  subsidiaries' ownership interest in the Target Center and related
acquisition documents;

              LASIK  shall  have  previously  granted  to  Lender  a first  lien
perfected  security  interest in all of LASIK's  ownership  interest in Borrower
through the execution and delivery of the Assignment  and Security  Agreement in
the form attached as Exhibit G4 to the Contribution Agreement and LASIK shall be
in compliance with all of its obligations thereunder;

          (g) if  Borrower  is using a  Development  Facility  Loan to  acquire,
     directly or  indirectly,  a 100% Target  Center,  Borrower shall cause such
     Target  Center to  execute a  security  agreement,  acceptable  in form and
     substance to Lender, granting to Lender or one of Lender's subsidiaries the
     highest  available  priority security interest in all of the assets of such
     Target Center; and
          (h)  Lender  shall  have  received  such  other  approvals,  opinions,
     documents,  certificates or evidences as Lender may reasonably  request (in
     form and substance reasonably  satisfactory to Lender). Each request for an
     Working  Capital  Advance or  Development  Facility  Loan shall be deemed a
     representation  by Borrower  that the  conditions  of this Section 3.2 have
     been met.
                                                    ARTICLE IV
                                     BORROWER'S REPRESENTATIONS AND WARRANTIES

         Borrower represents and warrants to Lender as follows:

          4.1  Good  Standing.  Borrower  is a  duly  formed  limited  liability
     company,  duly organized and in good  standing,  under the laws of Delaware
     and has the power to own its  property and to carry on its business in each
     jurisdiction in which Borrower operates. -------------

         4.2 Authority and Compliance.  Borrower has full power and authority to
enter into this  Agreement,  to make the  borrowing  hereunder,  to execute  and
deliver  the Loan  Documents  and to incur the  indebtedness  described  in this
Agreement,  all of which has been duly  authorized  by all proper and  necessary
action of its managers and members. No further consent or approval of any public
authority is required as a condition to the validity of any Loan  Document,  and
Borrower is in compliance with all laws and regulatory  requirements to which it
is subject.

          4.3 Binding  Agreement.  This  Agreement and other Loan Documents when
     issued and delivered  pursuant  hereto for value received will  constitute,
     valid and legally binding  obligations of Borrower in accordance with their
     terms. -----------------

          4.4 Litigation.  There are no proceedings pending or, to the knowledge
     of Borrower,  threatened  before any court or  administrative  agency which
     will or may have a material  adverse  effect on the financial  condition or
     operations of Borrower or any subsidiary,  except as disclosed to Lender in
     writing prior to the date of this Agreement.  To the knowledge of Borrower,
     there are no proceedings  pending or threatened  against any Target Center.
     ----------

          4.5 No Conflicting  Agreements.  There are no provisions of Borrower's
     organizational  documents  and no  provisions  of any  existing  agreement,
     mortgage,  indenture  or  contract  binding on Borrower  or  affecting  its
     property,  which would  conflict with or in any way prevent the  execution,
     delivery,   or   carrying   out  of  the  terms  of  the  Loan   Documents.
     -------------------------

          4.6  Ownership  of Assets.  Borrower  will at all times  maintain  its
     tangible property,  real and personal, in good order and repair taking into
     consideration reasonable wear and tear. -------------------

          4.7 Taxes.  All income  taxes and other taxes due and payable  through
     the date of this  Agreement  have been paid prior to  becoming  delinquent.
     -----

                                                     ARTICLE V
                                         BORROWER'S AFFIRMATIVE COVENANTS

         So long as Borrower may borrow under this  Agreement  and until payment
in full of the Working  Capital Note and all  Development  Facility  Notes,  and
performance of all other obligations of Borrower and Target Centers hereunder or
thereunder, Borrower covenants and agrees to do the following:

         5.1      Financial Statements.

                  (a)  Maintain,  and cause each Target  Center to  maintain,  a
         system of  accounting  satisfactory  to Lender and in  accordance  with
         generally accepted accounting principles consistently applied, and will
         permit  Lender's  officers or authorized  representatives  to visit and
         inspect  Borrower's  or  Target  Center's  books of  account  and other
         records  at such  reasonable  times and as often as Lender  may  desire
         during office hours and after  reasonable  notice to Borrower,  and pay
         the  reasonable  fees and  disbursements  of any  accountants  or other
         agents of Lender selected by Lender for the foregoing purposes.  Unless
         written notice of another location is given to Lender, Borrower's books
         and records will be located at Borrower's Address.

          (b) Furnish to Lender year end financial  statements,  of Borrower and
     each Target  Center,  to include  balance  sheet,  operating  statement and
     surplus   reconciliation,   together  with  an  officer's   certificate  of
     compliance with this Agreement  including  computations of all quantitative
     covenants, within 90 days after the end of each annual accounting period.
          (c) Furnish to Lender quarterly financial statements,  of Borrower and
     each Target Center, to include balance sheet and profit and loss statement,
     together with an officer's  certificate  of compliance  with this Agreement
     including computations of all quantitative covenants, within 45 days of the
     end of each such accounting period.
                  (d) With each balance sheet delivered under subsections (b) or
(c) of this Section 5.1, an aging of all Accounts Receivable.

          (e) Promptly provide Lender with such additional information,  reports
     or statements respecting the business operations and financial condition of
     Borrower or any Target Center,  as Lender may reasonably  request from time
     to time.
         5.2  Insurance.  Maintain,  and cause each Target  Center to  maintain,
insurance  with  responsible  insurance  companies  on  such  of its  respective
properties,  in such amounts and against such risks as is customarily maintained
by similar businesses operating in the same vicinity,  specifically to include a
policy  of fire  and  extended  coverage  insurance  covering  all  assets,  and
liability  insurance,  all  to be  with  such  companies  and  in  such  amounts
satisfactory  to Lender and to contain a mortgage  clause  naming  Lender as its
interest may appear. Evidence of such insurance will be supplied to Lender.

          5.3 Existence and Compliance.  Maintain,  and cause each Target Center
     to maintain, its organizational  existence in good standing and comply with
     all laws, regulations and governmental  requirements applicable to it or to
     any of its property, business operations and transactions. Borrower further
     agrees to provide  Lender  with  copies of all  instruments  filed with the
     Delaware Secretary of State amending and/or renewing Borrower's certificate
     of formation. ------------------------

          5.4 Adverse Conditions or Events. Promptly advise Lender in writing of
     any  condition,  event or act which  comes to its  attention  that would or
     might  materially  affect  Borrower's  or  any  Target  Center's  financial
     condition,  Lender's  rights  under  this  Agreement  or any  of  the  Loan
     Documents, and of any litigation filed against Borrower or to its knowledge
     against any Target Center. ----------------------------

         5.5      Taxes.  Pay all taxes as they become due and payable.

          5.6 Maintenance.  Maintain,  and cause each Target Center to maintain,
     all of its  respective  tangible  property  in good  condition  and repair,
     reasonable  wear and tear  excepted,  and make all  necessary  replacements
     thereof,  and preserve and maintain all licenses,  privileges,  franchises,
     certificates  and the like  necessary  for the  operation of its  business.
     -----------

          5.7  Application  of  Earnings.  Except as expressly  contemplated  in
     Section  4.3(e) of the  Contribution  Agreement,  pay all  available  funds
     toward  repayment of the Working Capital Note and any Development  Facility
     Notes,  regardless of whether  payment of such amounts  exceeds the minimum
     required  payments  under  the  Working  Capital  Note and the  Development
     Facility Notes. -----------------------

                                                    ARTICLE VI
                                           BORROWER'S NEGATIVE COVENANTS

         So long as Borrower may borrow under this  Agreement  and until payment
in full of the Working  Capital Note and all  Development  Facility  Notes,  and
performance of all other  obligations of Borrower or Target Center  hereunder or
thereunder, Borrower will not, and will cause each of the Target Centers to not,
without the prior written consent of Lender:

          6.1  Transfer of Assets.  Enter into any merger or  consolidation,  or
     sell, lease,  assign, or otherwise dispose of or transfer any assets except
     in the normal course of its business. ------------------

          6.2 Change in Ownership or Structure.  Dissolve or liquidate; become a
     party  to  any  merger  or  consolidation;  reorganize  as  a  professional
     corporation;  acquire by purchase,  lease or otherwise all or substantially
     all of the assets or capital stock of any  corporation or other entity;  or
     sell, transfer,  lease, or otherwise dispose of all or any substantial part
     of    its     respective     property     or    assets     or     business.
     --------------------------------

          6.3 Liens.  From and after the date hereof  grant,  suffer,  or permit
     liens  on or  security  interests  in its  respective  assets,  or  fail to
     promptly pay all lawful claims, whether for labor, materials, or otherwise,
     except for purchase money security interests arising in the ordinary course
     of its respective business. -----

          6.4 Loans. Make any loans,  advances or investments to or in any joint
     venture,   corporation  or  other  entity,   except  for  the  purchase  of
     obligations  of Lender or U.S.  Government  obligations  or the purchase of
     federally-insured certificates of deposit. -----

          6.5  Borrowings.  Except for  borrowing  or  incurring  open  accounts
     payable to  unaffiliated  third parties in the ordinary course of business,
     create,  incur,  assume,  or liable in any manner for any indebtedness (for
     borrowed  money,  deferred  payment  for  the  purchase  of  assets,  lease
     payments,  as surety or  guarantor  of the debt of another,  or  otherwise)
     other than to Lender in excess of $25,000  without  Lender's  prior written
     consent. ----------

          6.6  Violate  Other  Covenants.  Violate  or fail to  comply  with any
     covenants or agreements  regarding  other debt which will or would with the
     passage of time or upon demand  cause the  maturity of any other debt to be
     accelerated. -----------------------

          6.7 Equity Redemptions or Restructurings. Apply any of its property or
     assets to the  purchase,  retirement  or  redemption  of any of its  equity
     interests    or   in    any    way    amend    its    capital    structure.
     ------------------------------------

          6.8 Character of Business. Change the general character of business as
     conducted  at the  date  hereof,  or  engage  in any type of  business  not
     reasonably  related to its  business as presently  and normally  conducted.
     ---------------------

                                                    ARTICLE VII
                                      EVENTS OF DEFAULT; NOTICE; ACCELERATION

          7.1  Events  of  Default.  If one or more of the  following  events of
     default shall occur and continue  after thirty (30) days' written notice to
     Borrower,  all  outstanding  principal plus unpaid  interest of the Working
     Capital Note and each Development Facility Note, and any other indebtedness
     of Borrower to Lender,  shall  automatically be due and payable immediately
     and Lender shall have no further  obligation to fund under this  Agreement.
     -----------------

          (a) There shall be any breach or default  shall be made in the payment
     of any  installment of principal or interest upon the Working  Capital Note
     or any Development Facility Note, when due and payable, whether at maturity
     or otherwise; or
          (b) There  shall be any  breach or  default  (other  than by Lender or
     Prime Medical  Services,  Inc.) under any Loan Document,  the  Contribution
     Agreement, or any Transaction Document (other than those certain Consulting
     Agreements  with Dr.  Dulaney,  Dr.  Barnet and Mark  Rosenberg as required
     pursuant  to  the  Contribution  Agreement),   or  any  other  certificate,
     agreement or document contemplated hereby or thereby; or
          (c) Any  representation or warranty of Borrower contained herein or in
     any financial statement, certificate, report or opinion submitted to Lender
     in connection  with the Working  Capital Loan or any  Development  Facility
     Loan, or by Borrower pursuant to the requirements of this Agreement,  shall
     prove to have been  incorrect or  misleading  in any material  respect when
     made; or
          (d) Any  judgment  against  Borrower or any  attachment  or other levy
     against  the  property  of  Borrower  with  respect  to a claim  materially
     affecting Borrower's  financial status remains unpaid,  unstayed on appeal,
     undischarged, not bonded or not dismissed for a period of 30 days; or
          (e) The  bankruptcy,  death,  or  dissolution  of any guarantor of the
     Indebtedness; or
                  (f) Borrower makes an assignment for the benefit of creditors,
         admits in writing  its  inability  to pay its debts  generally  as they
         become due, files a petition in bankruptcy, is adjudicated insolvent or
         bankrupt,  petitions or applies to any tribunal for any receiver or any
         trustee  of  Borrower  or any  substantial  part  of  their  respective
         property,   commences  any  action   relating  to  Borrower  under  any
         reorganization,  arrangement,  readjustment  of  debt,  dissolution  or
         liquidation  law  or  statute  of  any  jurisdiction,  whether  now  or
         hereafter in effect, or if there is commenced against Borrower any such
         action,  or Borrower by any act indicates its consent to or approval of
         any trustee for Borrower or any  substantial  part of its property,  or
         suffers any such receivership or trustee to continue undischarged.

         7.2  Lender's  Remedies.  Upon the  occurrence  of an Event of Default,
Lender,  without notice of any kind,  except for any notice  required under this
Agreement or any other Loan Document, may, at Lender's option: (i) terminate its
obligation to fund any Working Capital Advance or any Development  Facility Loan
hereunder;  (ii) declare the Indebtedness,  in whole or in part, immediately due
and payable;  and/or (iii)  exercise any other rights and remedies  available to
Lender under this Agreement, any other Loan Document, or applicable laws; except
that upon the occurrence of an Event of Default described in subsection  7.1(f),
all the Indebtedness  shall  automatically  be immediately due and payable,  and
Lender's  obligation  to fund any  Working  Capital  Advance or any  Development
Facility Loan hereunder  shall  automatically  terminate,  without notice of any
kind (including  without limitation notice of intent to accelerate and notice of
acceleration) to Borrower or to any Target Center,  guarantor,  or to any surety
or endorser of any of the Notes, or to any other person.  Borrower,  each Target
Center,  and each guarantor,  surety,  and endorser of any of the Notes, and any
and all other parties  liable for the  Indebtedness  or any part thereof,  waive
demand,  notice  of  intent  to  demand,  presentment  for  payment,  notice  of
nonpayment,  protest,  notice of protest,  grace, notice of dishonor,  notice of
intent to accelerate maturity, notice of acceleration of maturity, and diligence
in collection.

         7.3 Right of Set-Off. Borrower hereby authorizes Lender, to the maximum
extent permitted under and in accordance with applicable laws, at any time after
the occurrence of an Event of Default which  continues  uncured,  to set-off and
apply  any and all  deposits,  funds or  assets at any time held and any and all
other  indebtedness  at any time  owing by  Lender  to or for the  credit or the
account of  Borrower  against  any and all  Indebtedness,  whether or not Lender
exercises  any  other  right  or  remedy  hereunder  and  whether  or  not  such
Indebtedness are then matured.

                                                   ARTICLE VIII
                                           GENERAL TERMS AND CONDITIONS

         8.1  Notices.  All  notices,  demands,  requests,  approvals  and other
communications  required or permitted hereunder shall be in writing and shall be
deemed to have been given when (a) presented  personally,  or (b) three (3) days
after  deposited in a regularly  maintained mail receptacle of the United States
Postal Service,  postage prepaid,  certified,  return receipt requested,  or (c)
upon receipt of confirmation after sending by facsimile transmission,  addressed
to  Borrower  or  Lender,  as the case may be, at the  respective  addresses  or
facsimile  number for notice set forth on the first page of this  Agreement,  or
such other  address or  facsimile  number as Borrower or Lender may from time to
time designate by written notice to the other.

          8.2 Entire Agreement and Modifications.  The Loan Documents,  together
     with the Contribution Agreement and Transaction  Documents,  constitute the
     entire  understanding and agreement between the undersigned with respect to
     the  transactions  arising in connection  with the Working Capital Loan and
     the  Development  Facility  Loans,  and supersede all prior written or oral
     understandings   and  agreements  between  the  undersigned  in  connection
     therewith.   No   provision   of  this   Agreement   or  the   other   Loan
     ----------------------------------  Documents may be modified,  waived,  or
     terminated  except by instrument  in writing  executed by the party against
     whom a modification,  waiver, or termination is sought to be enforced, and,
     in the case of Lender, executed by a Vice President or higher level officer
     of Lender.
          8.3  Severability.  In case any of the  provisions  of this  Agreement
     shall for any reason be held to be invalid, illegal, or unenforceable, such
     invalidity,  illegality,  or  unenforceability  shall not  affect any other
     provision hereof, and this Agreement shall be construed as if such invalid,
     illegal,  or  unenforceable  provision  had never  been  contained  herein.
     ------------

         8.4  Cumulative  Rights  and No  Waiver.  Lender  shall have all of the
rights and remedies  granted in the Loan  Documents  and  available at law or in
equity,  and these  same  rights and  remedies  shall be  cumulative  and may be
pursued separately,  successively, or concurrently against Borrower, at the sole
discretion of Lender.  Lender's  delay in exercising any right shall not operate
as a waiver thereof,  nor shall any single or partial  exercise by Lender of any
right preclude any other or future exercise thereof or the exercise of any other
right.  Any of Borrower's  covenants and  agreements may be waived by Lender but
only in  writing  signed by an  authorized  officer of Vice  President  level or
higher of Lender or any subsequent  owner or holder of any of the Notes.  Except
as otherwise  expressly  provided in this  Agreement  and in any Note,  Borrower
expressly waives any presentment,  demand, protest, notice of default, notice of
intent  to  accelerate,  notice  of  acceleration,  notice  of  intent to demand
payment,  or other notice of any kind. No notice to or demand on Borrower in any
case shall, of itself, entitle Borrower to any other or further notice or demand
in similar or other circumstances.  No delay or omission by Lender in exercising
any  power  or  right  hereunder  shall  impair  any  such  right or power or be
construed  as a waiver  thereof,  or the  exercise  of any other  right or power
hereunder.

          8.5  Form  and  Substance.  All  documents,  certificates,   insurance
     policies,  and other items  required  under this  Agreement  to be executed
     and/or  delivered  to  Lender  shall  be in form and  substance  reasonably
     satisfactory to Lender. ------------------

         8.6 Limitation on Interest: Maximum Rate. Lender and Borrower intend to
contract in strict  compliance  with  applicable  usury law from time to time in
effect.  To effectuate this intention,  Lender and Borrower  stipulate and agree
that none of the terms and provisions of any Note and any other  agreement among
such parties, whether now existing or arising hereafter, shall ever be construed
as a contract to pay interest for the use,  forbearance or detention of money in
excess of the Maximum Rate. If, from any possible  construction of any document,
interest would otherwise be payable to Lender in excess of the Maximum Rate, any
such  construction  shall be subject to the  provisions of this Section and such
document  shall be  automatically  reformed and the  interest  payable to Lender
shall be  automatically  reduced to the Maximum Rate permitted under  applicable
law,  without the  necessity of the  execution of any amendment or new document.
Neither  Borrower,  endorsers or other persons now or hereafter  becoming liable
for payment of any portion of the  principal  or interest of any Note shall ever
be liable for any  unearned  interest on the  principal  amount or shall ever be
required  to pay  interest  thereon  in excess of the  Maximum  Rate that may be
lawfully  charged under  applicable law from time to time in effect.  Lender and
any subsequent  holder of any Note expressly  disavow any intention to charge or
collect  unearned  or  excessive  interest  or finance  charges in the event the
maturity of any Note, is accelerated. If the maturity of any Note is accelerated
for any reason, whether as a result of a default under any Note, or by voluntary
prepayment,  or otherwise,  any amounts constituting interest, or adjudicated as
constituting  interest,  which  are  then  unearned  and  have  previously  been
collected  by Lender or any  subsequent  holder of any Note  shall be applied to
reduce the principal balance thereof then outstanding, or if such amounts exceed
the unpaid  balance of principal,  the excess shall be refunded to Borrower (and
Target Center,  as applicable).  In the event Lender or any subsequent holder of
any Note ever receives, collects or applies as interest any amounts constituting
interest or adjudicated as constituting  interest which would otherwise increase
the  interest to an amount in excess of the amount  permitted  under  applicable
law,  such amount  which  would be  excessive  interest  shall be applied to the
reduction of the unpaid  principal  balance of such Note,  and, if the principal
balances of such Note is paid in full,  any  remaining  excess  shall be paid to
Borrower (and Target Center, as applicable).  In determining  whether or not the
interest  paid or payable under the specific  contingencies  exceeds the Maximum
Rate allowed by applicable law, Borrower and Lender shall, to the maximum extent
permitted under applicable law, (i) characterize any non-principal payment as an
expense,  fee or  premium,  rather  than as  interest;  (ii)  exclude  voluntary
prepayments  and the effect  thereof;  (iii)  amortize,  prorate,  allocate  and
spread,  in equal  parts,  the total  amount of interest  throughout  the entire
contemplated  term of the applicable Note (as it may be renewed and extended) so
that the interest rate is uniform  throughout  the entire term of such Note. The
terms and  provisions of this section  shall  control and supersede  every other
provision of all existing and future agreements between Lender and Borrower (and
Target Center, as applicable).  As used in this Agreement,  "Maximum Rate" means
the maximum non-usurious interest rate that at any time or from time to time may
be contracted for, taken, reserved,  charged or received on the unpaid principal
or accrued past due interest  under  applicable  law and may be greater than the
applicable  rate,  the parties hereby  stipulating  and agreeing that Lender may
contract for, take,  reserve,  charge or receive interest up to the Maximum Rate
without penalty under any applicable law; and "applicable law" means the laws of
the State of Texas or the laws of the United States of America,  whichever  laws
allow the greater interest,  as such laws now exist or may be changed or amended
or come into effect in the future.  In the event  applicable law provides for an
interest  ceiling under  Chapter One of Title 79, Texas  Revised Civil  Statutes
Annotated, as amended, that ceiling shall be the indicated rate ceiling, subject
to any right  Lender may have in the future to change the method of  determining
the Maximum Rate.

          8.7  Third  Party  Beneficiary.  Borrower  acknowledges  that the bank
     syndication  under the senior credit  facility of Prime  Medical  Services,
     Inc. (as hereinafter supplemented,  modified, or replaced) is a third party
     beneficiary  to this  Agreement.  Except for the preceding  sentence,  this
     Agreement is for the sole benefit of Lender and Borrower and is not for the
     benefit of any third party. -----------------------

          8.8  Borrower  In  Control.  In no event  shall  Lender's  rights  and
     interests  under the Loan  Documents  be construed to give Lender the right
     to, or be deemed to  indicate  that  Lender is in control of the  business,
     management or properties of Borrower or any Target Center or has power over
     the daily management  functions and operating decisions made by Borrower or
     any Target Center. -------------------

          8.9 Use of  Financial  and Other  Information.  Borrower  agrees  that
     Lender shall be permitted to investigate and verify the accuracy of any and
     all information  furnished to Lender in connection with the Loan Documents,
     including without  limitation  financial  statements,  and to disclose such
     information,  or provide  copies of such  information,  to  representatives
     appointed by Lender, including independent accountants,  agents, attorneys,
     asset   investigators,    appraisers   and   any   other   persons   deemed
     --------------------------------------   necessary   by   Lender   to  such
     investigation.
         8.10  Collateral  Assignment of Loan  Documents.  Lender shall have the
right to  collaterally  assign all of its rights  under this  Agreement  and the
other Loan Documents to the third party beneficiaries  described in Section 8.7.
Lender shall have the right to disclose in confidence such financial information
regarding  Borrower as may be  necessary  to  complete  any such  assignment  or
attempted  assignment,  including without limitation,  all financial statements,
projections,  internal memoranda,  audits, reports, payment history,  appraisals
and any and all other  information and  documentation in Lender's files relating
to Borrower.  This  authorization  shall be irrevocable in favor of Lender,  and
Borrower  waives any claims  against Lender or the party  receiving  information
from Lender  regarding  disclosure of information in Lender's files, and further
waive any  alleged  damages  which may  result  from such  disclosure.  Borrower
acknowledges  that Lender intends to make a collateral  assignment of its rights
under this  Agreement  and the Loan  Documents for the benefit of one or more of
its or its  parent  company's  lenders  and will not be  authorized  to amend or
modify this  Agreement  or the Loan  Documents,  or grant  waivers of any of its
rights  thereunder  without  the prior  written  consent  of some or all of such
lenders.

          8.11 Further Assurances.  Borrower agrees to execute and deliver,  and
     cause each Target Center to execute and deliver,  to Lender,  promptly upon
     request from Lender,  such other and further documents as may be reasonably
     necessary  or  appropriate  to  consummate  the  transactions  contemplated
     herein. ------------------

          8.12 Number and Gender.  Whenever  used herein,  the  singular  number
     shall  include the plural and the plural the  singular,  and the use of any
     gender  shall  be  applicable  to  all  genders.  The  duties,   covenants,
     obligations,  and warranties of Borrower in this  Agreement  shall be joint
     and several  obligations of Borrower and of each Borrower if more than one.
     -----------------

          8.13 Captions.  The captions,  headings, and arrangements used in this
     Agreement  are for  convenience  only and do not in any way affect,  limit,
     amplify, or modify the terms and provisions hereof. --------

         8.14  Continuing  Agreement.  This is a  continuing  agreement  and all
rights,  powers,  and remedies of Lender under this Agreement and the other Loan
Documents  shall  continue  in full force and effect  until each Note is paid in
full as the same becomes due and payable and all other  Indebtedness is paid and
discharged, until Lender has no further obligation to advance moneys to Borrower
under this Agreement, and until Lender, upon request of Borrower, has executed a
written termination statement.  Furthermore,  the parties contemplate that there
may be times when no Indebtedness is owing, but notwithstanding such occurrence,
this Agreement (and all other Loan Documents) shall remain valid and shall be in
full force and effect as to subsequent Indebtedness and Advances,  provided that
Lender has not executed a written termination statement.

          8.15  Applicable  Law. This Agreement and the Loan Documents  shall be
     governed by and construed in accordance with the laws of the State of Texas
     and the laws of the United States  applicable to  transactions  within such
     state. --------------

          8.16 NO ORAL  AGREEMENTS.  THE WRITTEN LOAN  AGREEMENT  REPRESENTS THE
     FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
     OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT  ORAL AGREEMENTS OF THE PARTIES.
     THERE   ARE   NO   UNWRITTEN   ORAL   AGREEMENTS   BETWEEN   THE   PARTIES.



                                             [SIGNATURE PAGE FOLLOWS]






<PAGE>




                                                 SIGNATURE PAGE TO
                                                  LOAN AGREEMENT


         EXECUTED as of 1st day of September, 1999.

                                 BORROWER:

                                            PRIME/BDR ACQUISITION, L.L.C.

                                    By:  /s/ Ronald W. Barnet, M.D.
                                    Name: Ronald W. Barnet, M.D.
                                    Title: Manager

                                 LENDER:

                                            PRIME MEDICAL OPERATING, INC.

                                    By:  /s/ Cheryl Williams
                                    Name: Cheryl Williams
                                    Title: Treasurer





<PAGE>


                       LIMITED LIABILITY COMPANY AGREEMENT

                        OF PRIME/BDR ACQUISITION, L.L.C.
     Organized under the Delaware Limited Liability Company Act (the "Act").

                                   ARTICLE I.

                                NAME AND LOCATION

     Section 1.1. Name. The name of this limited  liability company is Prime/BDR
Acquisition, L.L.C. (the "Company").

         Section  1.2.  Members.  The  only  members  of the  Company  upon  the
execution of this Limited Liability Company Agreement (this  "Agreement")  shall
be Prime Medical Operating,  Inc, a Delaware  corporation  ("Prime"),  and LASIK
Investors L.L.C., a Delaware limited liability company  ("LASIK").  For purposes
of this  Agreement,  the "Members"  shall include such named members and any new
members admitted  pursuant to the terms of this Agreement,  but does not include
any person or entity who has ceased to be a member in the Company.

     Section 1.3. Principal Office. The principal office of the Company shall be
located in 1301 Capital of Texas Hwy., Suite C-300, Austin, Texas 78746-6550, or
such other location as may be selected by the Members.

     Section 1.4. Registered Agent and Address. The name of the registered agent
and the  address  of the  registered  office of the  Company as set forth in the
Certificate of Formation of the Company are:

                                            The Corporation Trust Company
                                            1209 Orange Street
                                            Wilmington, Delaware 19801

     Section 1.5.  Other  Offices.  Other offices and other  facilities  for the
transaction of business shall be located at such places as the Managers may from
time to time determine.

         Section 1.6  Contribution  Agreement.  The Company was initially formed
with a single member,  LASIK,  for the purpose of consummating  the transactions
contemplated by that certain Contribution Agreement dated effective September 1,
1999, by and among Prime, Prime Medical Services,  Inc., a Delaware  corporation
("PMSI"),  LASIK, Barnet Dulaney Eye Center,  P.L.L.C.,  an Arizona professional
limited  liability  company,  the Company,  Prime/BDEC  Acquisition,  L.L.C.,  a
Delaware limited liability  company,  David D. Dulaney,  M.D., Ronald W. Barnet,
M.D.,  and Mark  Rosenberg  (the  "Contribution  Agreement").  The parties  have
executed this Agreement upon  consummation of the  transactions  contemplated by
the  Contribution  Agreement.  This agreement  supercedes and replaces any prior
membership  agreement  or other  governing  or  organizational  document  of the
Company.

                                   ARTICLE II.

                                   MEMBERSHIP

     Section 2.1. Members' Interests.  The "Membership  Interest" of each Member
is set forth on Exhibit A.

     Section 2.2. Admission to Membership. The admission of new Members shall be
only by the unanimous  vote of the Members.  If new members are  admitted,  this
Agreement shall be amended to reflect each Member's revised Membership Interest.

     Section 2.3.  Property  Rights.  No Member shall have any right,  title, or
interest in any of the property or assets of the Company.

     Section  2.4.  Liability  of  Members.  No Member of the  Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment decree, or order of court.

         Section 2.5.  Transferability of Membership.  Except as provided below,
Membership  Interests in the Company are  transferable  only with the  unanimous
written  consent  of all  Members.  If such  unanimous  written  consent  is not
obtained when  required,  the  transferee  shall be entitled to receive only the
share of  profits  or other  compensation  by way of  income  and the  return of
contributions  to which  the  transferor  Member  otherwise  would be  entitled.
Notwithstanding  the  foregoing,  (i) the  Membership  Interests of Prime may be
freely  transferred,  without  consent,  to any  entity  that is then  owned  or
controlled, directly or indirectly, by PMSI (or its successor in interest), (ii)
the  Membership  Interests  of any  Member  may be freely  assigned,  pledged or
otherwise  transferred,  without  consent,  to  secure  any debt,  liability  or
obligation  owed to Prime by the  Company,  any Member or any entity  affiliated
with the  Company,  (iii) the  Membership  Interests of any Member may be freely
assigned,  pledged or otherwise  transferred,  without consent,  in favor of the
Lender(s)  under,  or by the  Lender(s)  as a result of the  enforcement  of any
security  interest arising pursuant to, that certain Senior Credit Facility (the
"Credit  Facility") of PMSI, (iv) the Membership  Interests of any Member may be
freely  transferred,  without  consent,  pursuant to and in accordance  with the
express terms and conditions of the Contribution Agreement,  and (iv) the pledge
by LASIK (pursuant to Section 6.3 of the Contribution Agreement) of its right to
receive  distributions  from the Company in respect of its  Membership  Interest
shall not be deemed to violate any provision of this Agreement..

         Section 2.6. Resignation of Members. A Member may not withdraw from the
Company except on the unanimous consent of the remaining  Members.  The terms of
the Members  withdrawal  shall be determined by agreement  between the remaining
Members and the withdrawing Member.

                                  ARTICLE III.

                                MEMBERS' MEETINGS

         Section  3.1.  Time and Place of Meeting.  All  meetings of the Members
shall be held at such  time and at such  place  within or  without  the State of
Delaware as shall be determined by the Managers.

         Section 3.2. Annual  Meetings.  In the absence of an earlier meeting at
such  time and place as the  Managers  shall  specify,  annual  meetings  of the
Members shall be held at the  principal  office of the Company on the date which
is thirty  (30) days after the end of the  Company's  fiscal year if not a legal
holiday,  and if a legal holiday,  then on the next full business day following,
at 10:00 a.m.,  at which  meeting the Members may transact  such business as may
properly be brought before the meeting.

     Section  3.3.  Special  Meetings.  Special  meetings  of the Members may be
called at any time by any Member.  Business transacted at special meetings shall
be confined to the purposes stated in the notice of the meeting.

         Section 3.4.  Notice.  Written or printed notice stating the place, day
and hour of any Members'  meeting,  and, in the case of a special  meeting,  the
purpose or purposes for which the meeting is called, shall be delivered not less
than ten (10) days nor more than thirty (30) days before the date of the special
meeting,  either  personally  or by mail,  by or at the  direction of the person
calling the meeting, to each Member entitled to vote at such meeting. If mailed,
such notice shall be deemed to be delivered three (3) days after it is deposited
in the United States mail,  postage prepaid,  to the Member at his address as it
appears on the records of the Company at the time of mailing.

         Section 3.5. Quorum. Members present in person or represented by proxy,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any meeting  shall  constitute  a quorum at all  meetings of the Members for the
transaction  of  business.  If,  however,  such  quorum  shall not be present or
represented at any meeting of the Members, the Members entitled to vote, present
in person or represented by proxy,  shall have power to adjourn the meeting from
time to time,  without notice other than  announcement  at the meeting,  until a
quorum shall be present or represented. When any adjourned meeting is reconvened
and a quorum shall be present or  represented,  any  business may be  transacted
which might have been  transacted at the meeting as originally  noticed.  Once a
quorum is constituted,  the Members present or represented by proxy at a meeting
may  continue  to  transact  business  until  adjournment,  notwithstanding  the
subsequent  withdrawal therefrom of such number of Members as to leave less than
a quorum.

         Section 3.6. Voting. When a quorum is present at any meeting,  the vote
of the Members, whether present or represented by proxy at such meeting, holding
more  than  fifty  percent  (50%) of the  total  votes  which may be cast at any
meeting shall be the act of the Members,  unless the vote of a different  number
is required by the Act, the  Certificate of Formation or this Limited  Liability
Company Agreement. Each Member shall be entitled to one vote for each percentage
point  represented by their  Membership  Interest.  Fractional  percentage point
interests shall be entitled to a corresponding fractional vote.

         Section  3.7.  Proxy.  Every  proxy must be  executed in writing by the
Member or by his duly authorized  attorney-in-fact,  and shall be filed with the
Secretary of the Company prior to or at the time of the meeting.  No proxy shall
be  valid  after  eleven  (11)  months  from the  date of its  execution  unless
otherwise  provided  therein.  Each proxy shall be  revocable  unless  expressly
provided therein to be irrevocable and unless otherwise made irrevocable by law.

         Section  3.8.  Action  by  Written  Consent.  Any  action  required  or
permitted  to be taken at any  meeting  of the  Members  may be taken  without a
meeting if a consent in  writing,  setting  forth the action so taken,  shall be
signed by all of the Members entitled to vote with respect to the subject matter
thereof,  and such  consent  shall have the same force and effect as a unanimous
vote of Members.

         Section 3.9. Meetings by Conference Telephone.  Members may participate
in and hold  meetings  of Members by means of  conference  telephone  or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

                                   ARTICLE IV.

                        MEMBERSHIP CAPITAL CONTRIBUTIONS

         Except  for  each  Member's  initial  capital   contribution   made  in
connection with the formation of the Company, no capital  contributions shall be
required  of any  Member  without  the  approval  of all the  Members  to  raise
additional capital, and only then proportionately as to each Member.

                                   ARTICLE V.

                             DISTRIBUTION TO MEMBERS

         The Company shall not  distribute (or allow to be  distributed)  to its
members,  with respect to their  respective  membership  interests,  any cash or
other  property  of the  Company  or its  subsidiaries  if,  at the  time of the
proposed   distribution,   any  amounts  (whether  principal  or  interest)  are
outstanding  under the Credit  Documents or the Target Center Lending  Documents
(as such terms are  defined in the  Contribution  Agreement).  Furthermore,  the
Company shall pay all  available  cash flow to Prime in payment of the Company's
outstanding obligations,  if any, under the Working Capital Line and Development
Facility (as such terms are defined in the Contribution Agreement), irrespective
of whether such payments exceed the minimum required  payments under the Working
Capital Line and Development Facility.  For purposes of allocating such payments
among any two or more of such  outstanding  obligations,  such payments shall be
allocated  pro rata,  based upon the  respective  balances of such  obligations,
unless (i) a greater  portion of the  payment is  required  to be paid  toward a
given  obligation in order to prevent a default with respect to that  obligation
(but only to the extent  necessary  to prevent  such a default)  or (ii)  eighty
percent (80%) of the managers of the Company elect to allocate the payments in a
different manner.

         Notwithstanding  the foregoing,  as long as no party other than PMSI or
Prime is in default under the  Contribution  Agreement or any other  Transaction
Document (as defined in the Contribution Agreement, but excluding,  however, the
Credit Documents and the Target Center Lending  Documents),  then, to the extent
that (but only to the extent that) the Company possesses the cash flow necessary
(in  the  reasonable  discretion  of a  majority  of its  managers)  to pay  its
liabilities in the ordinary course  consistent with past practices,  the Company
agrees to make  quarterly  estimates  of its taxable  income for the current tax
year  and,  if not  prohibited  by law,  distribute  quarterly  (the  "Quarterly
Distributions")  an amount that would cover the federal and state  income  taxes
required to be paid by its members with respect  such taxable  income,  based on
each member's then current proportionate interest in the Company,  assuming that
all members pay income taxes on the Company's  taxable  earnings at a rate equal
to the highest  effective  individual  tax rate in effect from time to time (the
"Assumed Tax Rate");  provided,  further,  that the Company shall  determine its
actual  taxable  income at the end of each taxable year and (A) if the Quarterly
Distributions  in a given year should  have been  higher  based on the amount of
actual taxable income for that year,  promptly  distribute the amounts necessary
to eliminate such  deficiency or (B) if the Quarterly  Distributions  in a given
year  should have been lower  based on the amount of actual  taxable  income for
that  year,  withhold  dollar  for  dollar  from the first  following  Quarterly
Distribution,  and then against  subsequent  Quarterly  Distributions  in a like
manner, the amounts necessary to eliminate such surplus.

         Subject to the foregoing,  the Managers shall determine,  in their sole
discretion,  the  amount  and  timing  of all  distributions  from the  Company.
Distributions  shall be  divided  among the  Members  in  accordance  with their
Membership Interests. Distributions in kind shall be made on the basis of agreed
value  as  determined  by the  Members.  In no  event  may  the  Company  make a
distribution  to  its  Members  if,  immediately  after  giving  effect  to  the
distribution,  all  liabilities  of the Company,  other than  liabilities to the
Members with respect to their  interests and  liabilities for which the recourse
of creditors is limited to  specified  property of the Company,  exceed the fair
value of the  Company's  assets;  except that the fair value of property that is
subject to  liability  for which  recourse of  creditors  is  limited,  shall be
included  in the  Company  assets  only to the extent that the fair value of the
property  exceeds that  liability.  Except as contemplated in this Article V, no
distributions  of cash or  other  assets  of the  Company  shall  be made to the
Members in their capacity as owners of the Company.

                                   ARTICLE VI.

              ALLOCATION OF NET PROFITS AND LOSSES FOR TAX PURPOSES

         For  accounting  and income tax  purposes,  all items of income,  gain,
loss,  deduction,  and  credit of the  Company  for any  taxable  year  shall be
allocated  among the  Members in  accordance  with their  respective  Membership
Interests,  except as may be otherwise  required by the Internal Revenue Code of
1986, as amended.

                                  ARTICLE VII.

                           DISSOLUTION AND WINDING UP

     Section 7.1.  Dissolution.  Notwithstanding  any  provision of the Act, the
Company shall be dissolved only upon the first of the following to occur:

               (a) Forty (40) years from the date of filing the  Certificate  of
          Formation of the Company;

               (b)  Written   consent  of  all  the  then  current   Members  to
          dissolution;

                  (c) The  bankruptcy of a Member,  unless there is at least one
         remaining Member and such Member or, if more than one remaining Member,
         all remaining Members agree to continue the Company and its business.

         Section 7.2.  Winding Up.  Unless the Company is continued  pursuant to
Section 7.1(c) of this Article VII., in the event of dissolution of the Company,
the Managers (excluding any Manager(s) holding office pursuant to designation by
a Member subject to bankruptcy  proceedings) shall wind up the Company's affairs
as soon  as  reasonably  practicable.  On the  winding  up of the  Company,  the
Managers  shall pay and/or  transfer the assets of the Company in the  following
order:

                    (a)  In  discharging   liabilities   (including  loans  from
               Members) and the expenses of concluding  the  Company's  affairs;
               and

                    (b) The  balance,  if any,  shall  be  divided  between  the
               Members in accordance with the Members' Membership Interests.

                                  ARTICLE VIII.

                                    MANAGERS

         Section 8.1. Selection of Managers.  Management of the Company shall be
vested in the  Managers.  Initially,  the Company  shall have five (5) Managers,
being Ken  Shifrin,  Cheryl  Williams,  and Joe Jenkins,  M.D.,  (as the initial
Manager designees of Prime), David D. Dulaney,  M.D., and Ronald W. Barnet, M.D.
(as the initial Manager  designees of LASIK).  Thereafter,  for so long as there
are five (5) Managers, (a) Prime shall be entitled to designate three (3) of the
Managers;  and (b) LASIK shall be entitled to designate the remaining two (2) of
the Managers.  Notwithstanding the foregoing,  a Member shall not be entitled to
designate any Manager unless its Membership Interest: (x) has not (other than as
allowed  under Section 2.5 of this  Agreement)  been  transferred,  repurchased,
assigned,  pledged,  hypothecated  or in any way  alienated;  and (y)  equals or
exceeds forty percent (40%) of the  aggregate  Membership  Interests;  provided,
however,  that if the immediately  preceding subsection (y) shall apply to LASIK
solely  because of an exercise by LASIK of its put rights  under  Section 9.8 of
the  Contribution  Agreement,  then LASIK  shall,  unless and until  there is an
additional decrease in it Membership Interest other than pursuant to Section 9.8
of the Contribution  Agreement, be entitled to designate only one Manager in the
manner provided above.  The Members may, by unanimous vote of all Members,  from
time to time,  change the number of  Managers  of the  Company and remove or add
Managers accordingly. A Manager shall serve as a Manager until their resignation
or removal  pursuant to Section 8.2 or 8.3 of this Article  VIII.  Managers need
not be residents of the State of Delaware or Members of the Company.

         Section 8.2. Resignations.  Each Manager shall have the right to resign
at any time upon  written  notice of such  resignation  to the  Members.  Unless
otherwise  specified in such written notice,  the resignation  shall take effect
upon the  receipt  thereof,  and  acceptance  of such  resignation  shall not be
necessary to make same effective.  The Member who designated a resigning manager
shall be entitled to designate  the  successor  thereto and all Members agree to
take such action as may be necessary to cause the election of all such successor
Managers.

         Section 8.3.  Removal of Managers.  Any Manager may be removed,  for or
without cause,  at any time, but only by the Member who designated such Manager,
upon the written notice to all Members.  The Member who designated  such removed
Manager  shall be entitled to designate  the  successor  thereto and all Members
agree to take such action as may be  necessary to cause the election of all such
successor Managers.

         Section  8.4.  General  Powers.  The  business of the Company  shall be
managed by its Managers, which may, by the vote or written consent in accordance
with this  Agreement,  exercise any and all powers of the Company and do any and
all such  lawful  acts and  things  as are not by the Act,  the  Certificate  of
Formation or this Limited Liability Company Agreement directed or required to be
exercised or done by the Members, including, but not limited to, contracting for
or incurring on behalf of the Company debts,  liabilities and other obligations,
without the consent of any other person, except as otherwise provided herein.

     Section 8.5. Place of Meetings.  The Managers of the Company may hold their
meetings,  both  regular  and  special,  either  within or without  the State of
Delaware.

         Section 8.6. Annual Meetings.  The annual meeting of the Managers shall
be held without further notice  immediately  following the annual meeting of the
Members, and at the same place, unless by unanimous consent of the Managers that
such time or place shall be changed.

     Section 8.7. Regular Meetings. Regular meetings of the Managers may be held
without  notice at such time and place as shall from time to time be  determined
by the Managers.

     Section  8.8.  Special  Meetings.  Special  meetings  of the Mangers may be
called by any Manager on seven (7) days notice to each Manager, with such notice
to be given personally, by mail or by telecopy, telegraph or mailgram.

         Section  8.9.  Quorum and Voting.  At all  meetings of the Managers the
presence of at least four (4) Managers  shall be  necessary  and  sufficient  to
constitute a quorum for the transaction of business, and the affirmative vote of
at least a majority of the  Managers  present at any meeting at which there is a
quorum shall be the act of the Managers, except as may be otherwise specifically
provided by the Act, the Contribution Agreement, the Certificate of Formation or
this Agreement. If a quorum shall not be present at any meeting of Managers, the
Managers  present there may adjourn the meeting from time to time without notice
other  than  announcement  at the  meeting,  until a quorum  shall  be  present.
Notwithstanding any voting, quorum, or other provisions of this Agreement to the
contrary,  the affirmative  vote of at least four (4) Managers shall be required
to effect any of the following actions:

               (a) any amendment, modification or waiver of any provision of the
          Company's Certificate of Formation or this Agreement;

               (b) effecting any mergers,  consolidations or combinations of the
          Company with other entities;

               (c)  dissolving,  liquidating,  or filing  bankruptcy  or seeking
          relief under any debtor relief law;

               (d) entering into a transaction  or other action with a Member or
          Manager;

                  (e) borrowing or incurring any  indebtedness,  other than open
         accounts  payable  to  unaffiliated  third  parties,  or  granting  any
         collateral  or  security  (by way of  guaranty  or  otherwise)  for any
         indebtedness or obligation,  that exceeds (in any single transaction or
         directly related series of transactions) $25,000;

                  (f) purchasing or leasing assets or property, or entering into
         any  contract  or  obligation,  which  obligates  the Company to pay in
         excess  of  $25,000  in  one  or  any   directly   related   series  of
         installments;

               (g) selling, leasing or otherwise transferring  substantially all
          of the  Company's  assets  other  than in the  ordinary  course of the
          Company's business;

                  (h)  except  as  expressly  set forth in  Section  9.12 of the
         Contribution Agreement, allocating to the Company any costs or expenses
         that are paid or  incurred by any Member or its  affiliates  (excluding
         the Company),  or paid by the Company but reimbursable by any Member or
         its affiliates (excluding the Company), in each instance;

                  (i)  issuance of any ownership interest in the Company; and

                  (j)  disposition,  sale,  assignment or other  transfer by the
         Company  of any  interest  it owns in the  Company,  except  that  such
         interest may be extinguished  without the approval  required under this
         Section.

         Section 8.10.  Committees.  The Managers  may, by resolution  passed by
eighty percent (80%) of the Managers,  designate  committees,  each committee to
consist  of two or more  Managers  (at  least  one of  which  must be a  Manager
designee of Prime and one of which must be a Manager  designee of LASIK),  which
committees  shall have such power and authority and shall perform such functions
as may be provided in such  resolution.  Such committee or committees shall have
such name or names as may be  designated  by the Managers and shall keep regular
minutes of their proceedings and report the same to the Managers when required.

         Section  8.11.  Compensation  of Managers.  The Members  shall have the
authority  to  provide,  by  unanimous  approval,  that  any  one or more of the
Managers  shall not be  compensated,  and may, by  unanimous  approval,  fix any
compensation  (which may include  expenses) they elect to pay to any one or more
of the Managers.

         Section  8.12.  Action by  Written  Consent.  Any  action  required  or
permitted  to be  taken  at any  meeting  of the  Managers  or of any  committee
designated  by the Managers may be taken  without a meeting if written  consent,
setting  forth the  action so taken,  is signed by all the  Managers  or of such
committee,  and such consent shall have the same force and effect as a unanimous
vote at a meeting.

         Section 8.13. Meetings by Conference Telephone.  Managers or members of
any committee  designated by the Managers may  participate in and hold a meeting
of the Managers or such  committee by means of  conference  telephone or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

     Section  8.14.  Liability of Managers.  No Manager of the Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment, decree, or order of the court.

         Section 8.15.  Specific Power of Managers.  The Managers shall have the
authority to enter into and execute all  documents in relation to the  formation
of the Company  including,  but not limited to,  issuance of the  Certificate of
Formation and this Limited Liability Company Agreement.

                                   ARTICLE IX.

                                     NOTICES

         Section 9.1. Form of Notice.  Whenever under the provisions of the Act,
the Certificate of Formation or this Limited  Liability Company Agreement notice
is required to be given to any Manager or Member, and no provision is made as to
how such notice shall be given,  notice shall not be construed to mean  personal
notice only, but any such notice may also be given in writing,  by mail, postage
prepaid,  addressed  to such Manager or Member at such address as appears on the
books of the Company, or by telecopy, telegraph or mailgram. Any notice required
or  permitted  to be given by mail  shall be deemed  to be given  three (3) days
after it is deposited, postage prepaid, in the United States mail as aforesaid.

         Section 9.2. Waiver. Whenever any notice is required to be given to any
Manager or Member of the Company under the provision of the Act, the Certificate
of Formation or this Limited  Liability Company  Agreement,  a waiver thereof in
writing signed by the person or persons entitled to such notice,  whether signed
before or after the time stated in such waiver,  shall be deemed  equivalent  to
the giving of such notice.

                                   ARTICLE X.

                                    OFFICERS

         Any Manager may also serve as an officer of the  Company.  The Managers
may  designate  one or more persons who are not Managers of the Company to serve
as officers and may designate the titles of all officers.  The initial  officers
of the Company shall be: Ken Shifrin,  Chairman of the Board; Joe Jenkins, M.D.,
President;  Cheryl  Williams,  Vice  President,  Secretary  and Chief  Financial
Officer;  and Mark Rosenberg,  Vice President.  Unless  otherwise  provided in a
resolution of the Members or Managers the officers of the Company shall have the
powers  designated  with  respect to such  offices  under the  Delaware  Limited
Liability Company Act, and any successor statute, as amended from time-to-time.

                                   ARTICLE XI.

                                    INDEMNITY

         Section 11.1.  Indemnification.  The Company shall indemnify any person
who was or is a party or is  threatened  to be made a party  to any  threatened,
pending or  completed  action,  suit or  proceeding,  whether  civil,  criminal,
administrative, arbitrative or investigative, any appeal in such an action, suit
or  proceeding  and any  inquiry  or  investigation  that  could lead to such an
action,  suit or proceeding  (whether or not by or in the right of the Company),
by reason of the fact that such person is or was a manager, officer, employee or
agent of the  Company or is or was  serving at the  request of the  Company as a
director,  manager, officer, partner, venturer,  proprietor,  trustee, employee,
agent or similar  functionary  of another  corporation,  employee  benefit plan,
other enterprise,  or other entity, against all judgments,  penalties (including
excise and similar taxes), fines, settlements and reasonable expenses (including
attorneys'  fees and court  costs)  actually and  reasonably  incurred by him in
connection with such action,  suit or proceeding to the fullest extent permitted
by any  applicable  law,  and such  indemnity  shall inure to the benefit of the
heirs,  executors and administrators of any such person so indemnified  pursuant
to this Article XI. The right to indemnification  under this Article XI shall be
a contract  right and shall not be deemed  exclusive of any other right to which
those seeking  indemnification may be entitled under any law, bylaw,  agreement,
vote of members or disinterested managers or otherwise, both as to action in his
official  capacity  and as to action in  another  capacity  while  holding  such
office. Any repeal or amendment of this Article XI by the Members of the Company
or by changes in  applicable  law shall,  to the extent  permitted by applicable
law, be prospective only, and shall not adversely affect the  indemnification of
any person who may be indemnified at the time of such repeal or amendment.

         Section   11.2.   Indemnification   Not   Exclusive.   The   rights  of
indemnification  and reimbursement  provided for in this Article XI shall not be
deemed  exclusive  of any  other  rights  to which  any such  Manager,  officer,
employee or agent may be  entitled  under the  Certificate  of  Formation,  this
Limited  Liability  Company  Agreement,  agreement  or vote of Members,  or as a
matter of law or otherwise.

         Section  11.3.  Other  Indemnification  Clauses.   Notwithstanding  the
foregoing,   this  Article  XI  shall  not  be  construed  to   contradict   the
indemnification   provision  of  the  Contribution  Agreement.   Notwithstanding
anything  contained  herein,  this Article XI shall be ineffectual and shall not
permit or require  indemnification for all, or any, losses, costs,  liabilities,
claims or expenses arising, directly or indirectly,  from any action or omission
permitting or requiring indemnification under the Contribution Agreement; and in
no event may any  indemnity be allowed  under this  Agreement or pursuant to any
provision   of  the  Act  for  an  amount  paid  or  payable   pursuant  to  the
indemnification provisions of the Contribution Agreement.

                                  ARTICLE XII.

                                  MISCELLANEOUS

     Section 12.1. Fiscal Year. The fiscal year of the Company shall be fixed by
resolution of the Managers.

     Section 12.2.  Records.  At the expense of the Company,  the Managers shall
maintain  records and accounts of all  operations of the Company.  At a minimum,
the Company shall keep at its principal place of business the following records:

               (a) A current list of the name and last known mailing  address of
          each Member;

               (b) A current list of each Member's Membership Interest;

                  (c) A  copy  of  the  Certificate  of  Formation  and  Limited
         Liability Company Agreement of the Company, and all amendments thereto,
         together with executed copies of any powers of attorney;

               (d) Copies of the  Federal,  state,  and local income tax returns
          and reports for the Company's six most recent tax years; and

               (e)  Correct  and  complete  books and  records of account of the
          Company.

         Section 12.3. Seal. The Company may by resolution of the Managers adopt
and have a seal, and said seal may be used by causing it or a facsimile  thereof
to be  impressed  or  affixed or in any manner  reproduced.  Any  officer of the
Company shall have authority to affix the seal to any document requiring it.

     Section 12.4. Agents.  Every Manager and Officer is an agent of the Company
for the purpose of the business. The act of a Manager or Officer,  including the
execution  in the name of the Company of any  instrument  for carrying on in the
usual way the business of the Company, binds the Company.

         Section 12.5. Checks. All checks,  drafts and orders for the payment of
money,  notes  and other  evidences  of  indebtedness  issued in the name of the
Company  shall be  signed  by such  officer,  officers,  agent or  agents of the
Company  and in such  manner  as  shall  from  time to  time  be  determined  by
resolution of the Managers. In the absence of such determination by the Mangers,
such  instruments  shall  be  signed  by  the  Treasurer  or the  Secretary  and
countersigned  by the  President  or a Vice  President  of the  Company,  if the
Company has such officers.

     Section 12.6.  Deposits.  All funds of the Company shall be deposited  from
time to time to the credit of the  Company in such  banks,  trust  companies  or
other depositories as the Managers may select.

         Section  12.7.  Annual  Statement.  The Managers  shall present at each
annual  meeting,  and,  when called for by vote of the  Members,  at any special
meeting of the Members, a full and clear statement of the business and condition
of the Company.

         Section 12.8.  Financial  Statements.  As soon as practicable after the
end of each fiscal year of the  Company,  a balance  sheet as at the end of such
fiscal year,  and a profit and loss  statement  for the period  ended,  shall be
distributed  to the  Members,  along with such tax  information  (including  all
information  returns) as may be necessary for the  preparation of each Member of
its Federal,  state and local income tax returns.  The balance  sheet and profit
and loss statement  referred to in the previous  sentence may be as shown on the
Company's federal income tax return.

         Section 12.9. Binding Arbitration.  Any controversy between the parties
regarding  this  Agreement and any claims  arising out of this  Agreement or its
breach  shall be submitted  to  arbitration  by either  party.  The  arbitration
proceedings shall be conducted by a single arbitrator pursuant to the Commercial
Arbitration Rules of the American Arbitration Association. The arbitration shall
be conducted in Dallas,  Texas and the arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

                                  ARTICLE XIII.

                                   AMENDMENTS

         Section 13.1.  Amendments.  This  Agreement may be altered,  amended or
repealed and a new limited liability  company agreement may be adopted,  only in
accordance  with the  provisions  of Section 8.9,  but  otherwise at any regular
meeting or at any special meeting called for that purpose,  or by execution of a
written consent in accordance with the provisions of Section 3.8.

         Section 13.2. When Limited  Liability  Company  Agreement Silent. It is
expressly recognized that when the Limited Liability Company Agreement is silent
or in conflict with the  requirements  of the Act as to the manner of performing
any Company function, the provisions of the Act shall control.

                            [Signature page follows]


<PAGE>

                                SIGNATURE PAGE TO

                                             LIMITED LIABILITY COMPANY AGREEMENT

         IN WITNESS WHEREOF,  the undersigned  Members hereby adopt this Limited
Liability  Company  Agreement as the Limited  Liability Company Agreement of the
Company, effective as of the 1st day of September, 1999.

                                              LASIK Investors, L.L.C.

                                              By: /s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                              By: /s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager

                                              Prime Medical Operating, Inc.

                                               By: /s/ Cheryl Williams

                                               Printed Name: Cheryl Williams

                                               Title: Treasurer



<PAGE>
                                    EXHIBIT A

                               OWNERSHIP INTERESTS

Name                                                     Ownership Percentage

Prime                                                           60%

LASIK                                                           40%






                       LIMITED LIABILITY COMPANY AGREEMENT
                        OF PRIME/BDEC ACQUISITION, L.L.C.
     Organized under the Delaware Limited Liability Company Act (the "Act").

                                   ARTICLE I.
                                NAME AND LOCATION

     Section 1.1. Name. The name of this limited liability company is Prime/BDEC
Acquisition, L.L.C. (the "Company"). ----

         Section  1.2.  Members.  The  only  members  of the  Company  upon  the
execution of this Limited Liability Company Agreement (this  "Agreement")  shall
be Prime Medical Operating,  Inc, a Delaware corporation  ("Prime"),  and Barnet
Dulaney Eye Center,  P.L.L.C., an Arizona professional limited liability company
("BDEC"). For purposes of this Agreement, the "Members" shall include such named
members and any new members  admitted  pursuant to the terms of this  Agreement,
but does not  include  any person or entity who has ceased to be a member in the
Company.

     Section 1.3. Principal Office. The principal office of the Company shall be
located in 1301 Capital of Texas Hwy., Suite C-300, Austin, Texas 78746-6550, or
such other location as may be selected by the Members. ----------------

     Section 1.4. Registered Agent and Address. The name of the registered agent
and the  address  of the  registered  office of the  Company as set forth in the
Certificate of Formation of the Company are: -----------------------------
                                            The Corporation Trust Company
                                            1209 Orange Street
                                            Wilmington, Delaware 19801

     Section 1.5.  Other  Offices.  Other offices and other  facilities  for the
transaction of business shall be located at such places as the Managers may from
time to time determine. -------------

         Section 1.6  Contribution  Agreement.  The Company was initially formed
with a single member,  BDEC, for the purpose of  consummating  the  transactions
contemplated by that certain Contribution Agreement dated effective September 1,
1999, by and among Prime, Prime Medical Services,  Inc., a Delaware  corporation
("PMSI"), BDEC, the Company,  Prime/BDR Acquisition,  L.L.C., a Delaware limited
liability  company,  LASIK  Investors,  L.L.C.,  a  Delaware  limited  liability
company, David D. Dulaney, M.D., Ronald W. Barnet, M.D., and Mark Rosenberg (the
"Contribution  Agreement").  The  parties  have  executed  this  Agreement  upon
consummation of the  transactions  contemplated by the  Contribution  Agreement.
This agreement  supercedes and replaces any prior membership  agreement or other
governing or organizational document of the Company.

                                                    ARTICLE II.
                                                    MEMBERSHIP

     Section 2.1. Members' Interests.  The "Membership  Interest" of each Member
is set forth on Exhibit A. ------------------ ---------

     Section 2.2. Admission to Membership. The admission of new Members shall be
only by the vote of the Managers  pursuant to Section 8.9 hereof. If new Members
are admitted,  this Agreement shall be amended to reflect each Member's  revised
Membership Interest. -----------------------

     Section 2.3.  Property  Rights.  No Member shall have any right,  title, or
interest in any of the property or assets of the Company. ---------------

     Section  2.4.  Liability  of  Members.  No Member of the  Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment decree, or order of court. --------------------

         Section 2.5.  Transferability of Membership.  Except as provided below,
Membership  Interests in the Company are  transferable  only with the  unanimous
written  consent  of all  Members.  If such  unanimous  written  consent  is not
obtained when  required,  the  transferee  shall be entitled to receive only the
share of  profits  or other  compensation  by way of  income  and the  return of
contributions  to which  the  transferor  Member  otherwise  would be  entitled.
Notwithstanding  the  foregoing,  (i) the  Membership  Interests of Prime may be
freely  transferred,  without  consent,  to any  entity  that is then  owned  or
controlled,  directly or indirectly, by Prime Medical Services, Inc., a Delaware
corporation (or its successor in interest), (ii) the Membership Interests of any
Member  may be  freely  assigned,  pledged  or  otherwise  transferred,  without
consent,  to  secure  any debt,  liability  or  obligation  owed to Prime by the
Company,  any  Member  or any  entity  affiliated  with the  Company,  (iii) the
Membership Interests of any Member may be freely assigned,  pledged or otherwise
transferred,  without  consent,  in  favor  of the  Lender(s)  under,  or by the
Lender(s)  as a result  of the  enforcement  of any  security  interest  arising
pursuant to, that certain  Senior  Credit  Facility  (the "Credit  Facility") of
PMSI, and (iv) the pledge by BDEC  (pursuant to Section 6.3 of the  Contribution
Agreement) of its right to receive  distributions from the Company in respect of
its  Membership  Interest  shall not be deemed to violate any  provision of this
Agreement.

     Section 2.6.  Resignation  of Members.  A Member may not withdraw  from the
Company except on the unanimous consent of the remaining  Members.  The terms of
the Members  withdrawal  shall be determined by agreement  between the remaining
Members and the withdrawing Member. ----------------------

                                                   ARTICLE III.
                                                 MEMBERS' MEETINGS

     Section 3.1.  Time and Place of Meeting.  All meetings of the Members shall
be held at such time and at such place  within or without  the State of Delaware
as shall be determined by the Managers. -------------------------

     Section 3.2. Annual Meetings.  In the absence of an earlier meeting at such
time and place as the Managers  shall  specify,  annual  meetings of the Members
shall be held at the principal office of the Company on the date which is thirty
(30) days after the end of the Company's fiscal year if not a legal holiday, and
if a legal holiday, then on the next full business day following, at 10:00 a.m.,
at which  meeting the  Members may  transact  such  business as may  properly be
brought before --------------- the meeting.

     Section  3.3.  Special  Meetings.  Special  meetings  of the Members may be
called at any time by any Member.  Business transacted at special meetings shall
be   confined   to  the   purposes   stated  in  the  notice  of  the   meeting.
- ----------------

         Section 3.4.  Notice.  Written or printed notice stating the place, day
and hour of any Members'  meeting,  and, in the case of a special  meeting,  the
purpose or purposes for which the meeting is called, shall be delivered not less
than ten (10) days nor more than thirty (30) days before the date of the special
meeting,  either  personally  or by mail,  by or at the  direction of the person
calling the meeting, to each Member entitled to vote at such meeting. If mailed,
such notice shall be deemed to be delivered three (3) days after it is deposited
in the United States mail,  postage prepaid,  to the Member at his address as it
appears on the records of the Company at the time of mailing.

         Section 3.5. Quorum. Members present in person or represented by proxy,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any meeting  shall  constitute  a quorum at all  meetings of the Members for the
transaction  of  business.  If,  however,  such  quorum  shall not be present or
represented at any meeting of the Members, the Members entitled to vote, present
in person or represented by proxy,  shall have power to adjourn the meeting from
time to time,  without notice other than  announcement  at the meeting,  until a
quorum shall be present or represented. When any adjourned meeting is reconvened
and a quorum shall be present or  represented,  any  business may be  transacted
which might have been  transacted at the meeting as originally  noticed.  Once a
quorum is constituted,  the Members present or represented by proxy at a meeting
may  continue  to  transact  business  until  adjournment,  notwithstanding  the
subsequent  withdrawal therefrom of such number of Members as to leave less than
a quorum.

         Section  3.6.  Voting.  Members  shall  only  be  required  to  vote in
instances  or with  respect  to  matters  where  member  voting is  required  by
applicable  law or to the extent  expressly  contemplated  in Section 8.1.  With
respect to any act or  transaction  that  requires a vote by the  Members  under
applicable law, the affirmative  vote of not less than three (3) of the Managers
shall also be  required  in order to  approve  the act or  transaction,  in each
instance. Subject to the foregoing, when a quorum is present at any meeting, the
vote of the Members,  whether  present or  represented by proxy at such meeting,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any  meeting  shall be the act of the  Members,  unless the vote of a  different
number is required by the Act,  the  Certificate  of  Formation  or this Limited
Liability Company Agreement.  Each Member shall be entitled to one vote for each
percentage point represented by their Membership Interest. Fractional percentage
point  interests  shall be  entitled to a  corresponding  fractional  vote.  The
provisions of this Section shall not  interfere  with the  provisions of Section
8.9 relating to acts or transactions requiring the written approval of three (3)
or more Managers.  Each Member acknowledges and agrees that, in the event of any
exercise of the Repurchase  Option,  as defined in the  Contribution  Agreement,
each Member will vote its entire  Membership  Interest in favor of  transferring
the Company's assets pursuant to the Repurchase Option.

     Section 3.7.  Proxy.  Every proxy must be executed in writing by the Member
or by his  duly  authorized  attorney-in-fact,  and  shall  be  filed  with  the
Secretary of the Company prior to or at the time of the meeting.  No proxy shall
be  valid  after  eleven  (11)  months  from the  date of its  execution  unless
otherwise  provided  therein.  Each proxy shall be  revocable  unless  expressly
provided therein to be irrevocable and unless otherwise made irrevocable by law.
- -----

     Section 3.8. Action by Written Consent. Any action required or permitted to
be taken at any  meeting  of the  Members  may be taken  without a meeting  if a
consent in writing, setting forth the action so taken, shall be signed by all of
the Members  entitled to vote with respect to the subject  matter  thereof,  and
such  consent  shall  have the same  force  and  effect as a  unanimous  vote of
Members. -------------------------

     Section 3.9. Meetings by Conference  Telephone.  Members may participate in
and hold  meetings  of  Members  by means of  conference  telephone  or  similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction     of    any     business     on    the     ground     that     the
- -------------------------------- meeting is not lawfully called or convened.

                                   ARTICLE IV.
                        MEMBERSHIP CAPITAL CONTRIBUTIONS

         Except  for  each  Member's  initial  capital   contribution   made  in
connection with the formation of the Company, no capital  contributions shall be
required  of any  Member  without  the  approval  of all the  Members  to  raise
additional capital, and only then proportionately as to each Member.

                                                    ARTICLE V.
                                              DISTRIBUTION TO MEMBERS

         At the end of each calendar quarter, subject only to the qualifications
and  limitations  set forth below,  the Company shall  distribute  its available
excess  earnings to its members,  to be divided  among them in  accordance  with
their Membership Interests.  Distributions in kind shall be made on the basis of
agreed value as determined by the Members.  Notwithstanding  the foregoing,  the
Company  may  not  make a  distribution  to its  Members  to  the  extent  that,
immediately  after giving effect to the  distribution,  all  liabilities  of the
Company,  other than  liabilities to the Members with respect to their interests
and  liabilities  for which the  recourse of  creditors  is limited to specified
property of the  Company,  exceed the fair value of the Company  assets;  except
that the fair value of property that is subject to liability for which  recourse
of  creditors  is limited,  shall be included in the Company  assets only to the
extent that the fair value of the property exceeds that liability.

                                   ARTICLE VI.
              ALLOCATION OF NET PROFITS AND LOSSES FOR TAX PURPOSES

         For  accounting  and income tax  purposes,  all items of income,  gain,
loss,  deduction,  and  credit of the  Company  for any  taxable  year  shall be
allocated  among the  Members in  accordance  with their  respective  Membership
Interests,  except as may be otherwise  required by the Internal Revenue Code of
1986, as amended.

                                  ARTICLE VII.
                           DISSOLUTION AND WINDING UP

     Section 7.1.  Dissolution.  Notwithstanding  any  provision of the Act, the
Company  shall be  dissolved  only  upon the  first of the  following  to occur:
- -----------

          (a) Forty  (40)  years  from the date of  filing  the  Certificate  of
     Formation of the Company;

          (b) Written consent of all the then current Members to dissolution;

          (c) The bankruptcy of a Member, unless there is at least one remaining
     Member and such Member or, if more than one remaining Member, all remaining
     Members  agree to  continue  the  Company and its  business.  Section  7.2.
     Winding Up. Unless the Company is continued  pursuant to Section  7.1(c) of
     this Article VII., in the event of dissolution of the Company, the Managers
     (excluding  any  Manager(s)  holding  office  pursuant to  designation by a
     Member  subject to  bankruptcy  proceedings)  shall  wind up the  Company's
     affairs  as  soon  as  reasonably  practicable.  On the  winding  up of the
     Company,  the Managers shall pay and/or  transfer the assets of the Company
     in the following order: ----------

          (a) In discharging  liabilities (including loans from Members) and the
     expenses of concluding the Company's affairs; and

                  (b) The balance,  if any, shall be divided between the Members
in accordance with the Members' Membership Interests.

                                  ARTICLE VIII.
                                    MANAGERS

         Section 8.1. Selection of Managers.  Management of the Company shall be
vested in the  Managers.  Initially,  the Company  shall have four (4) Managers,
being Ken  Shifrin,  Joe Jenkins,  M.D.,  (as the initial  Manager  designees of
Prime),  David D.  Dulaney,  M.D.  and Ronald W. Barnet,  M.D.,  (as the initial
Manager  designees  of  BDEC).  Thereafter,  for so long as  there  are four (4)
Managers,  (a) Prime shall be entitled to designate two (2) of the Managers; and
(b) BDEC shall be entitled to designate  the  remaining two (2) of the Managers.
Notwithstanding  the foregoing,  a Member shall not be entitled to designate any
Manager unless its Membership Interest: (x) has not (other than as allowed under
Section 2.5 of this Agreement) been transferred, repurchased, assigned, pledged,
hypothecated  or in any way  alienated;  and (y) equals or exceeds forty percent
(40%) of the aggregate Membership Interests.  The Members may, by unanimous vote
of all Members,  from time to time, change the number of Managers of the Company
and remove or add Managers accordingly. A Manager shall serve as a Manager until
their  resignation  or removal  pursuant to Section  8.2 or 8.3 of this  Article
VIII.  Managers need not be residents of the State of Delaware or Members of the
Company.

          Section 8.2. Resignations. Each Manager shall have the right to resign
     at any time upon written notice of such resignation to the Members.  Unless
     otherwise  specified in such written  notice,  the  resignation  shall take
     effect upon the receipt thereof,  and acceptance of such resignation  shall
     not be  necessary  to make same  effective.  The  Member who  designated  a
     resigning  manager shall be entitled to designate the successor thereto and
     all Members agree to take such action as may be  ------------  necessary to
     cause the election of all such successor Managers.

          Section 8.3. Removal of Managers.  Any Manager may be removed,  for or
     without  cause,  at any time,  but only by the Member who  designated  such
     Manager,  upon the written notice to all Members. The Member who designated
     such removed  Manager shall be entitled to designate the successor  thereto
     and all Members  agree to take such action as may be necessary to cause the
     election of all such successor Managers. -------------------

         Section  8.4.  General  Powers.  The  business of the Company  shall be
managed by its Managers, which may, by the vote or written consent in accordance
with this  Agreement,  exercise any and all powers of the Company and do any and
all such  lawful  acts and  things  as are not by the Act,  the  Certificate  of
Formation or this Limited Liability Company Agreement directed or required to be
exercised or done by the Members, including, but not limited to, contracting for
or incurring on behalf of the Company debts,  liabilities and other obligations,
without the consent of any other person, except as otherwise provided herein.

          Section 8.5.  Place of Meetings.  The Managers of the Company may hold
     their  meetings,  both  regular and special,  either  within or without the
     State of Delaware. -----------------

          Section 8.6. Annual Meetings. The annual meeting of the Managers shall
     be held without further notice immediately  following the annual meeting of
     the  Members,  and at the same place,  unless by  unanimous  consent of the
     Managers that such time or place shall be changed. ---------------

          Section 8.7. Regular Meetings. Regular meetings of the Managers may be
     held  without  notice at such time and place as shall  from time to time be
     determined by the Managers. ----------------

          Section 8.8. Special Meetings.  Special meetings of the Mangers may be
     called by any Manager on seven (7) days notice to each  Manager,  with such
     notice  to be  given  personally,  by mail  or by  telecopy,  telegraph  or
     mailgram. ----------------

         Section  8.9.  Quorum and Voting.  At all  meetings of the Managers the
presence of at least three (3) Managers  shall be necessary  and  sufficient  to
constitute a quorum for the transaction of business, and the affirmative vote of
at least a majority of the  Managers  present at any meeting at which there is a
quorum shall be the act of the Managers, except as may be otherwise specifically
provided by the Act, the Contribution Agreement, the Certificate of Formation or
this Agreement. If a quorum shall not be present at any meeting of Managers, the
Managers  present there may adjourn the meeting from time to time without notice
other  than  announcement  at the  meeting,  until a quorum  shall  be  present.
Notwithstanding  any  other  Member  or  Manager  voting  or  quorum  provisions
contained  in  this  Agreement,  the  following  acts  or  transactions  by,  or
involving,  the Company shall  require the prior  written  approval of three (3)
Managers  (unless and to the extent a particular act or transaction is expressly
required of the Company pursuant to the terms and provisions of the Contribution
Agreement or any Transaction Document):

          (a) Any  amendment to the Company's  Certificate  of Formation or this
     Agreement.

          (b)  Mergers,  consolidations  or  combinations  of the  Company  with
     another limited liability company or other entity.

                  (c)  Purchase by the Company of any  interest in the  Company,
irrespective of the source of such interest.

          (d) Disposition,  sale, assignment or other transfer by the Company of
     any  interest  it owns in the  Company,  except that such  interest  may be
     extinguished without the approval required under this Article.

                  (e)      Issuance of any interest in the Company to any party.

                  (f) Dissolving,  liquidating,  or filing bankruptcy or seeking
relief under any debtor relief law.

                  (g)  Election  or removal of  officers,  and  establishing  or
changing the compensation for Managers, officers or other employees.

          (h) Not making any cash distributions to its Members that are required
     by this Agreement to be made, or making any distributions to its Members of
     cash or property that are prohibited under this Agreement.

          (i) Sale, lease or other transfer of all or  substantially  all of the
     Company's  assets,  or any assets other than in the ordinary  course of the
     Company's business.

                  (j)  Initiating  or  settling  any  litigation  or  regulatory
proceeding, or confessing any judgment.

                  (k) Hiring or  changing  the  Company's  accountants  or legal
counsel.

                  (l) Opening or closing bank or other depository accounts,  and
establishing or changing the signature  withdrawal authority with respect to any
such accounts.

          (m) Borrowing or incurring any indebtedness,  other than open accounts
     payable to  unaffiliated  third  parties,  or granting  any  collateral  or
     security  (by  way of  guaranty  or  otherwise)  for  any  indebtedness  or
     obligation.

                  (n)  Engaging in any act or  transaction  not in the  ordinary
course of the Company's business.

          (o)  Purchasing  or leasing  assets or property,  or entering into any
     contract or  obligation,  which  obligates  the Company to pay in excess of
     $10,000 in the aggregate in one or any series of installments.

          (p) Doing any  business  other than the  conduct of the  Business  (as
     defined in the Contribution Agreement) or causing a change in the nature of
     the business or the legal name of the Company.

                  (q)  Entering  into a  transaction  or other  action  with any
Manager, officer or Member.

          (r) Waiving, refusing to enforce, amending, restating,  superseding or
     modifying  any of the  provisions  of  this  Agreement  or any  Transaction
     Document, including, without limitation, the Collocation Agreement.

          (s) Taking any other  action  which,  by the terms of this  Agreement,
     requires  the  approval  or consent of not less than  seventy-five  percent
     (75%) of the Members.

          (t) Except as  expressly  set forth in the  Collocation  Agreement  or
     Section 9.12 of the Contribution  Agreement,  allocating to the Company any
     costs or expenses that are paid or incurred by any Member or its affiliates
     (excluding  the Company),  or paid by the Company but  reimbursable  by any
     Member or its affiliates (excluding the Company), in each instance.

          (u) With respect to the business and  operations of Newco II conducted
     or to be conducted  at or near the  location of 4800 N. 22nd St.,  Phoenix,
     Arizona,  waiving,   amending,   supplementing  or  modifying  any  of  the
     professional  fees,  facility fees or fee  allocations  by Newco II, to the
     extent such amounts or allocations were utilized in preparing the pro forma
     financial statements of Newco II attached to the Collocation Agreement.

          (v) With respect to the business and  operations of Newco II conducted
     or to be  conducted  at any  other  future  office  or  business  locations
     (including  without  limitation,  the office  located at 555 E. River Road,
     Tucson,  Arizona),  adopting any  professional  fees,  facility fees or fee
     allocations.

         Any of the  above  stated  actions  taken by the  Company  without  the
necessary manager approval is void ab initio.

         Section 8.10.  Committees.  The Managers  may, by resolution  passed by
eighty percent (80%) of the Managers,  designate  committees,  each committee to
consist  of two or more  Managers  (at  least  one of  which  must be a  Manager
designee of Prime and one of which must be a Manager  designee  of BDEC),  which
committees  shall have such power and authority and shall perform such functions
as may be provided in such  resolution.  Such committee or committees shall have
such name or names as may be  designated  by the Managers and shall keep regular
minutes of their proceedings and report the same to the Managers when required.

          Section  8.11.  Compensation  of Managers.  The Members,  by unanimous
     approval,  shall have the  authority to provide that any one or more of the
     Managers shall not be compensated,  and may, by unanimous approval, fix any
     compensation  (which may include  expenses) they elect to pay to any one or
     more of the Managers. ------------------------

          Section  8.12.  Action by  Written  Consent.  Any action  required  or
     permitted  to be taken at any meeting of the  Managers or of any  committee
     designated  by the  Managers  may be taken  without  a meeting  if  written
     consent,  setting forth the action so taken,  is signed by all the Managers
     or of such committee, and such consent shall have the same force and effect
     as a unanimous vote at a meeting. -------------------------

         Section 8.13. Meetings by Conference Telephone.  Managers or members of
any committee  designated by the Managers may  participate in and hold a meeting
of the Managers or such  committee by means of  conference  telephone or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

          Section 8.14.  Liability of Managers.  No Manager of the Company shall
     be personally  liable for any debts,  liabilities,  or  obligations  of the
     Company,  including  under a  judgment,  decree,  or  order  of the  court.
     ---------------------

          Section 8.15. Specific Power of Managers.  The Managers shall have the
     authority  to enter into and  execute  all  documents  in  relation  to the
     formation  of the Company  including,  but not limited to,  issuance of the
     Certificate  of Formation  and this Limited  Liability  Company  Agreement.
     --------------------------

                                                    ARTICLE IX.
                                                      NOTICES

         Section 9.1. Form of Notice.  Whenever under the provisions of the Act,
the Certificate of Formation or this Limited  Liability Company Agreement notice
is required to be given to any Manager or Member, and no provision is made as to
how such notice shall be given,  notice shall not be construed to mean  personal
notice only, but any such notice may also be given in writing,  by mail, postage
prepaid,  addressed  to such Manager or Member at such address as appears on the
books of the Company, or by telecopy, telegraph or mailgram. Any notice required
or  permitted  to be given by mail  shall be deemed  to be given  three (3) days
after it is deposited, postage prepaid, in the United States mail as aforesaid.

          Section  9.2.  Waiver.  Whenever any notice is required to be given to
     any Manager or Member of the Company  under the  provision  of the Act, the
     Certificate of Formation or this Limited  Liability  Company  Agreement,  a
     waiver thereof in writing signed by the person or persons  entitled to such
     notice,  whether  signed  before or after the time  stated in such  waiver,
     shall be deemed equivalent to the giving of such notice. ------

                                                    ARTICLE X.
                                                     OFFICERS


         Any Manager may also serve as an officer of the  Company.  The Managers
may  designate  one or more persons who are not Managers of the Company to serve
as officers and may designate the titles of all officers.  The initial  officers
of the Company shall be: Ken Shifrin,  Chairman of the Board; Joe Jenkins, M.D.,
President;  Cheryl  Williams,  Vice  President,  Secretary  and Chief  Financial
Officer;  and Mark Rosenberg,  Vice President.  Unless  otherwise  provided in a
resolution of the Members or Managers the officers of the Company shall have the
powers  designated  with  respect to such  offices  under the  Delaware  Limited
Liability Company Act, and any successor statute, as amended from time-to-time.

                                                    ARTICLE XI.
                                                     INDEMNITY

         Section 11.1.  Indemnification.  The Company shall indemnify any person
who was or is a party or is  threatened  to be made a party  to any  threatened,
pending or  completed  action,  suit or  proceeding,  whether  civil,  criminal,
administrative, arbitrative or investigative, any appeal in such an action, suit
or  proceeding  and any  inquiry  or  investigation  that  could lead to such an
action,  suit or proceeding  (whether or not by or in the right of the Company),
by reason of the fact that such person is or was a manager, officer, employee or
agent of the  Company or is or was  serving at the  request of the  Company as a
director,  manager, officer, partner, venturer,  proprietor,  trustee, employee,
agent or similar  functionary  of another  corporation,  employee  benefit plan,
other enterprise,  or other entity, against all judgments,  penalties (including
excise and similar taxes), fines, settlements and reasonable expenses (including
attorneys'  fees and court  costs)  actually and  reasonably  incurred by him in
connection with such action,  suit or proceeding to the fullest extent permitted
by any  applicable  law,  and such  indemnity  shall inure to the benefit of the
heirs,  executors and administrators of any such person so indemnified  pursuant
to this Article XI. The right to indemnification  under this Article XI shall be
a contract  right and shall not be deemed  exclusive of any other right to which
those seeking  indemnification may be entitled under any law, bylaw,  agreement,
vote of members or disinterested managers or otherwise, both as to action in his
official  capacity  and as to action in  another  capacity  while  holding  such
office.  Any repeal or amendment of this Article XI by the Managers (pursuant to
Section  8.9  hereof)  or by  changes in  applicable  law  shall,  to the extent
permitted by applicable law, be prospective only, and shall not adversely affect
the  indemnification  of any person who may be  indemnified  at the time of such
repeal or amendment.

          Section   11.2.   Indemnification   Not   Exclusive.   The  rights  of
     indemnification and reimbursement provided for in this Article XI shall not
     be deemed exclusive of any other rights to which any such Manager, officer,
     employee or agent may be entitled under the Certificate of Formation,  this
     Limited Liability Company Agreement,  agreement or vote of Members, or as a
     matter of law or otherwise. -----------------------------

         Section  11.3.  Other  Indemnification  Clauses.   Notwithstanding  the
foregoing,   this  Article  XI  shall  not  be  construed  to   contradict   the
indemnification   provision  of  the  Contribution  Agreement.   Notwithstanding
anything  contained  herein,  this Article XI shall be ineffectual and shall not
permit or require  indemnification for all, or any, losses, costs,  liabilities,
claims or expenses arising, directly or indirectly,  from any action or omission
permitting or requiring indemnification under the Contribution Agreement; and in
no event may any  indemnity be allowed  under this  Agreement or pursuant to any
provision   of  the  Act  for  an  amount  paid  or  payable   pursuant  to  the
indemnification provisions of the Contribution Agreement.

                                                   ARTICLE XII.
                                                   MISCELLANEOUS

          Section  12.1.  Fiscal Year.  The fiscal year of the Company  shall be
     fixed by resolution of the Managers. -----------

          Section  12.2.  Records.  At the expense of the Company,  the Managers
     shall maintain records and accounts of all operations of the Company.  At a
     minimum,  the Company  shall keep at its  principal  place of business  the
     following records: -------

          (a) A current list of the name and last known mailing  address of each
     Member;
                  (b)      A current list of each Member's Membership Interest;

          (c) A copy of the  Certificate  of  Formation  and  Limited  Liability
     Company Agreement of the Company, and all amendments thereto, together with
     executed copies of any powers of attorney;

                  (d) Copies of the Federal, state, and local income tax returns
and reports for the Company's six most recent tax years; and

                  (e) Correct and  complete  books and records of account of the
Company.

          Section  12.3.  Seal.  The Company may by  resolution  of the Managers
     adopt  and  have a seal,  and  said  seal  may be used by  causing  it or a
     facsimile  thereof to be impressed or affixed or in any manner  reproduced.
     Any officer of the Company  shall have  authority  to affix the seal to any
     document requiring it. ----

          Section  12.4.  Agents.  Every  Manager and Officer is an agent of the
     Company for the purpose of the  business.  The act of a Manager or Officer,
     including  the execution in the name of the Company of any  instrument  for
     carrying  on in the  usual  way the  business  of the  Company,  binds  the
     Company. ------

         Section 12.5. Checks. All checks,  drafts and orders for the payment of
money,  notes  and other  evidences  of  indebtedness  issued in the name of the
Company  shall be  signed  by such  officer,  officers,  agent or  agents of the
Company  and in such  manner  as  shall  from  time to  time  be  determined  by
resolution of the Managers. In the absence of such determination by the Mangers,
such  instruments  shall  be  signed  by  the  Treasurer  or the  Secretary  and
countersigned  by the  President  or a Vice  President  of the  Company,  if the
Company has such officers.

          Section  12.6.  Deposits.  All funds of the Company shall be deposited
     from  time  to time to the  credit  of the  Company  in such  banks,  trust
     companies or other depositories as the Managers may select. --------

          Section 12.7.  Annual  Statement.  The Managers  shall present at each
     annual meeting a full and clear  statement of the business and condition of
     the Company. ----------------

         Section 12.8.  Financial  Statements.  As soon as practicable after the
end of each fiscal year of the  Company,  a balance  sheet as at the end of such
fiscal year,  and a profit and loss  statement  for the period  ended,  shall be
distributed  to the  Members,  along with such tax  information  (including  all
information  returns) as may be necessary for the  preparation of each Member of
its Federal,  state and local income tax returns.  The balance  sheet and profit
and loss statement  referred to in the previous  sentence may be as shown on the
Company's federal income tax return.

          Section 12.9. Binding Arbitration. Any controversy between the parties
     regarding  this  Agreement and any claims  arising out of this Agreement or
     its  breach  shall  be  submitted  to  arbitration  by  either  party.  The
     arbitration  proceedings shall be conducted by a single arbitrator pursuant
     to  the   Commercial   Arbitration   Rules  of  the  American   Arbitration
     Association.  The arbitration  shall be conducted in Dallas,  Texas and the
     arbitrator   shall   have   the   right  to  award   actual   damages   and
     -------------------  attorney fees and costs,  but shall not have the right
     to award punitive, exemplary or consequential damages against either party.

                                  ARTICLE XIII.
                                   AMENDMENTS

          Section 13.1.  Amendments.  This Agreement may be altered,  amended or
     repealed and a new limited liability company agreement may be adopted, only
     in  accordance  with the  provisions  of Section 8.9, but  otherwise at any
     regular  meeting or at any special  meeting called for that purpose,  or by
     execution of a written consent in accordance with the provisions of Section
     3.8. ----------

          Section 13.2. When Limited  Liability  Company Agreement Silent. It is
     expressly  recognized that when the Limited  Liability Company Agreement is
     silent or in conflict with the  requirements of the Act as to the manner of
     performing any Company  function,  the provisions of the Act shall control.
     -----------------------------------------------

                                             [Signature page follows]




<PAGE>


                                                 SIGNATURE PAGE TO
                                        LIMITED LIABILITY COMPANY AGREEMENT

         IN WITNESS WHEREOF,  the undersigned  Members hereby adopt this Limited
Liability  Company  Agreement as the Limited  Liability Company Agreement of the
Company, effective as of the 1st day of September, 1999.


                                          Barnet Dulaney Eye Center, P.L.L.C.


                                             By: /s/ Ronald W. Barnet, M.D.
                                                Ronald W. Barnet, M.D., manager

                                             By:/s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager




                                          Prime Medical Operating, Inc.

                                            By: /s/ Cheryl Williams
                                            Printed Name: Cheryl Williams
                                            Title: Treasurer



<PAGE>



                                                     EXHIBIT A
                                                OWNERSHIP INTERESTS

Name                                                      Ownership Percentage

Prime                                                              60%

BDEC                                                               40%






<PAGE>



                                             NON-COMPETITION AGREEMENT
         This Non-Competition Agreement (this "Agreement") is entered into as of
the 1st day of September, 1999 (the "Effective Date"), by Scott A. Perkins, M.D.
(the  "Equity  Holder"),  who is an equity  owner of Barnet  Dulaney Eye Center,
P.L.L.C., an Arizona professional limited liability company ("BDEC"),  and LASIK
Investors,  L.L.C.,  a Delaware limited  liability  company  ("LASIK"),  for the
benefit of Prime Medical Services,  Inc., a Delaware corporation ("PMSI"), Prime
Medical   Operating,   Inc.,  a  Delaware   corporation   ("Prime"),   Prime/BDR
Acquisition,   L.L.C.,  a  Delaware  limited   liability  company  ("Newco  I"),
Prime/BDEC  Acquisition,  L.L.C., a Delaware limited  liability  company ("Newco
II"), BDEC, LASIK, Ronald W. Barnet,  M.D.  ("Barnet"),  David D. Dulaney,  M.D.
("Dulaney") and Mark Rosenberg  ("Rosenberg")  (PMSI,  Prime, Newco I, Newco II,
BDEC, LASIK,  Barnet,  Dulaney and Rosenberg are referred to herein individually
as a "Beneficiary" and collectively as "Beneficiaries").
                                                     RECITALS:
         WHEREAS,  the  Equity  Holder  is an equity  owning  member of BDEC and
LASIK.
         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Newco I, Newco II, Prime, PMSI, BDEC, LASIK,  Barnet,  Dulaney,  and
Rosenberg   are   consummating   that  certain   Contribution   Agreement   (the
"Contribution Agreement"), dated effective September 1, 1999.
         WHEREAS, in order to induce each of the Beneficiaries to consummate the
         transactions  contemplated by the  Contribution  Agreement,  the Equity
         Holder has agreed to certain  restrictions  on the activities of Equity
         Holder and his Affiliates (as hereinafter defined),  which restrictions
         the Equity Holder deems  reasonable  and  appropriate.  THEREFORE,  the
         parties hereto agree as follows:
                                                    AGREEMENTS:
         1. Confidentiality  Agreement.  Equity Holder acknowledges that through
his  relationship  with  BDEC  and  LASIK,  he will be  exposed  to  Proprietary
Information (as defined below) of Newco I, Newco II and/or each of their present
or future affiliates (which includes,  without  limitation,  BDEC, LASIK, Prime,
PMSI and each of their  present or future  affiliates)  (the party  owning  such
Proprietary   Information  is  referred  to  as  the  "Discloser"),   that  such
Proprietary  Information  is unique and valuable and that such  Discloser  would
suffer irreparable injury if its Proprietary  Information were divulged to those
in  competition  with  Discloser.   "Proprietary   Information"   shall  be  all
information  concerning  Discloser which Equity Holder acquires,  or to which he
has  access  through  his  relationship  with BDEC or  LASIK,  that has not been
publicly  disclosed  by  Discloser  or that is not a matter of common  knowledge
among  Discloser's  competitors,  including,  but not  limited  to,  information
relating to any  inventions,  processes,  software,  formulae,  plans,  devices,
compilations  of  information,   technical  data,   mailing  lists,   management
strategies, business distribution methods, names of suppliers (of both goods and
services)  and   customers,   names  of  employees  and  terms  of   employment,
arrangements  entered into with  suppliers  and  customers,  including,  but not
limited to, proposed expansion plans of Discloser,  marketing and other business
and pricing  strategies,  and trade  secrets of Discloser.  Notwithstanding  the
foregoing,  Proprietary  Information  shall not include  information or material
that would otherwise be Proprietary  Information if such information or material
is owned solely by BDEC and not  materially  used or relied on in the conduct of
the Business (as defined in the Contribution Agreement).
          Except with prior written approval of Discloser,  Equity Holder agrees
     that he will not, at any time after the Closing, as such term is defined in
     the  Contribution  Agreement:  (i)  directly or  indirectly,  disclose  any
     Proprietary  Information  to any person  except the  employees,  agents and
     consultants  of Newco I,  Newco II and/or  Discloser  who need to know such
     Proprietary  Information in connection with their relationship with Newco I
     or Newco II nor (ii) use Proprietary Information in any way, except for the
     purposes and benefit of Newco I or Newco II.
         Within  forty-eight  (48) hours of termination of his ownership of BDEC
and LASIK,  whether voluntary or involuntary,  Equity Holder will deliver to the
appropriate Discloser (without retaining copies thereof) all documents,  records
or other  memorializations  including copies of documents and any notes which he
has  prepared  that  contain   Proprietary   Information,   all  other  tangible
Proprietary  Information  in his  possession  or control and all of  Discloser's
credit cards, keys, equipment,  vehicles,  supplies and other materials that are
in his possession or under his control.
         2. Non-Competition Agreement. Equity Holder, hereby agrees that, at all
times during which the provisions of ARTICLE VIII of the Contribution  Agreement
are in effect,  and at all times until five (5) years after either LASIK and its
affiliates  (excluding PMSI,  Prime, and the subsidiaries of either of them), or
Prime and its affiliates  (excluding  LASIK),  no longer own any equity or other
interest in Newco I,  Equity  Holder will not  directly  or  indirectly,  either
through any kind of ownership  (other than ownership of securities of a publicly
held  corporation  of which he owns less than five  percent (5%) of any class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
advisor, consultant,  co-partner or in any individual or representative capacity
whatever,  either for his own  benefit or for the  benefit of any other  person,
corporation  or  other  entity,  without  the  prior  written  consent  of  each
Beneficiary,  commit any of the following  acts,  which acts shall be considered
violations of this covenant not to compete:
                  (a) Except through Newco I or its  subsidiaries,  or Newco II,
directly or indirectly engage in, or provide,  anywhere within a fifty (50) mile
radius of any center or facility that provides Refractive Surgery (as defined in
the Contribution  Agreement) and is owned, directly or indirectly,  partially or
wholly,  by Newco I or a subsidiary of Newco I  (collectively,  the  "Restricted
Area"),  any services (other than services included in the practice of medicine)
related to (i) the  operating of centers or facilities  that provide  Refractive
Surgery,  (ii) the  manufacture,  maintenance,  refurbishing,  repair,  sale, or
leasing of any equipment related to or necessary for the operating of centers or
facilities that provide  Refractive  Surgery,  or (iii) providing any management
services,  training  or  consulting  services  related to any of the  activities
described in (i) or (ii);
                  (b) Except through Newco I or its  subsidiaries,  or Newco II,
directly  or  indirectly  provide,  anywhere  within the  Restricted  Area,  (i)
facilities,  equipment  and  non-physician  personnel  for  the  performance  by
physicians of Refractive Surgery, (ii) the marketing,  scheduling and management
of Refractive  Surgery (but  excluding  marketing,  scheduling and management of
patients for treatment by Equity Holder), (iii) the credentialing and scheduling
of physicians to perform Refractive Surgery and (iv) the billing,  collecting or
accounting  for the  use of any  such  facilities,  equipment  or  non-physician
personnel;
          (c)  Directly  or  indirectly  request  or advise  any  person,  firm,
     physician,  corporation or other entity having a business relationship with
     Newco I or any of its subsidiaries,  Prime,  LASIK, BDEC, Barnet,  Dulaney,
     Rosenberg,  or any affiliate or related entity of any of them, to withdraw,
     curtail, or cancel its business with such person or entity; or

          (d) Directly or indirectly  hire any employee of Newco I or any of its
     subsidiaries,  Prime,  LASIK,  BDEC,  Barnet,  Dulaney,  Rosenberg,  or any
     affiliate  or  related  entity  of any of them,  or induce  or  attempt  to
     influence any employee of Newco I or any of its subsidiaries, Prime, LASIK,
     BDEC, Barnet,  Dulaney,  Rosenberg, or any such affiliate or related entity
     to terminate his or her employment with such person or entity.

          3.  Exclusivity.  Equity Holder  acknowledges  that any acquisition or
     development of a Target Center (as defined in the  Contribution  Agreement)
     by Equity Holder through an entity not owned (wholly or partially, directly
     or  indirectly)  by Newco I shall be subject to the provisions of Section 2
     of this Agreement, regardless of whether such acquisition or development is
     contemplated  by or provided for in the  provisions  of ARTICLE VIII of the
     Contribution Agreement.

          4. Agreement.  Equity Holder has reviewed and carefully considered the
     provisions  of  Sections 1 and 2 of this  Agreement  and,  having  done so,
     agrees that the restrictions applicable to him as set forth therein (a) are
     fair and reasonable with respect to time,  geographic  area and scope,  (b)
     are not unduly  burdensome to him, and (c) are reasonably  required for the
     protection  of the  interests of the  Beneficiaries  for whose benefit such
     restrictions were agreed upon.

          5. Remedies.  Equity Holder agrees that a violation on his part of any
     applicable  covenant  contained in Sections 1 or 2 of this  Agreement  will
     cause the  Beneficiaries,  for whose benefit such  restrictions were agreed
     upon, irreparable damage for which remedies at law may be insufficient, and
     for that reason, he agrees that any of the Beneficiaries  shall be entitled
     as a matter of right to equitable remedies,  including specific performance
     and injunctive  relief,  therefor.  The right to specific  performance  and
     injunctive  relief shall be  cumulative  and in addition to whatever  other
     remedies,  at law or in equity, that the Beneficiaries may have, including,
     specifically, recovery of additional damages.

         6. Affiliates. For purposes of this Agreement, an "Affiliate" of Equity
Holder means any person married to, or any minor child of, Equity Holder and any
corporation, partnership or other entity that, at the date hereof or at any time
during the term hereof,  is controlled by, or under common control with,  Equity
Holder.  "Control" (and its derivatives),  in this context, means the possession
of,  directly or  indirectly,  the power to direct or cause the direction of the
management of the  applicable  corporation,  partnership  or other entity either
through the  ownership  of voting  securities  (or other equity  interests),  by
contract,  or by ownership of a membership  of a nonstock  corporation  or other
entity  enabling  Equity  Holder to elect one or more  members of the  governing
board of that nonstock corporation or other entity.

          7. Control of Affiliates' Actions.  Equity Holder will timely exercise
     all of his rights and powers to cause each of his Affiliates to comply with
     the terms of this Agreement. ------------------------------

          8. Indemnity.  Equity Holder agrees to indemnify, defend and hold each
     Beneficiary  harmless from and against any and all loss,  damage,  cost and
     expense  (including  attorneys'  fees) that may  result  from any breach or
     threatened  breach of this  Agreement by Equity  Holder or any Affiliate of
     Equity Holder. ---------

         9.       Miscellaneous.
          (a)  Amendments.  This Agreement may be modified or amended only by an
     instrument in writing executed by Equity Holder and each Beneficiary.
                  (b) Headings. The headings contained in this Agreement are for
                  reference  purposes  only and shall not  affect in any way the
                  meaning or  interpretation  of this  Agreement.  (c) Governing
                  Law.  This  Agreement  shall  be  construed  and  enforced  in
                  accordance  with the internal laws of the State of Texas,  and
                  not the conflicts of law provisions thereof.
          (d)  Parties  Bound.  This  Agreement  shall  be  binding  upon and be
     enforceable against the Equity Holder and Equity Holder's  Affiliates,  and
     their respective successors and representatives. This Agreement shall inure
     to the  benefit  of  each  Beneficiary  and  their  respective  successors,
     representatives and assigns. -------------
                  (e) Invalid  Provisions.  If any  provision of this  Agreement
(including, without limitation, any provision relating to the activities covered
by, or time period of, the covenants  contained in Section 2 of this  Agreement)
is held to be illegal,  invalid or  unenforceable  under  present or future laws
effective during the term hereof, such provision shall be fully severable;  this
Agreement  shall be  construed  and  enforced  as if such  illegal,  invalid  or
unenforceable  provision  had never  comprised a part hereof;  and the remaining
provisions  shall  remain in full force and effect and shall not be  affected by
the illegal,  invalid or unenforceable  provision or by its severance  herefrom.
Furthermore,  in lieu of such illegal, invalid or unenforceable provision, there
shall be added  automatically as a part of this Agreement a provision as similar
in terms to such illegal,  invalid or unenforceable provision as may be possible
and be legal, valid and enforceable.
          (f) Construction.  This Agreement shall be construed without regard to
     the  identity  of the person who drafted  the  various  provisions  of this
     Agreement. Each and every provision of this Agreement shall be construed as
     though all of the  parties  participated  equally in the  drafting  of this
     Agreement.  Consequently,  Equity Holder  acknowledges  and agrees that any
     rule  of  construction  that a  document  is to be  construed  against  the
     drafting party shall not be applicable to this Agreement. ------------
          (g) Defined Terms. Any capitalized terms not otherwise defined in this
     Agreement  shall  have the same  meaning  as set forth in the  Contribution
     Agreement. -------------
                                             [Signature page follows]



<PAGE>


                                                 SIGNATURE PAGE TO
                                             NON-COMPETITION AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:                                       /s/Scott A. Perkins, M.D.
                                                     Scott A. Perkins, M.D.





<PAGE>


                                             NON-COMPETITION AGREEMENT
         This Non-Competition Agreement (this "Agreement") is entered into as of
the 1st day of September,  1999 (the  "Effective  Date"),  by Robert B. Pinkert,
O.D. (the "Equity Holder"), who is an equity owner of Barnet Dulaney Eye Center,
P.L.L.C., an Arizona professional limited liability company ("BDEC"),  and LASIK
Investors,  L.L.C.,  a Delaware limited  liability  company  ("LASIK"),  for the
benefit of Prime Medical Services,  Inc., a Delaware corporation ("PMSI"), Prime
Medical   Operating,   Inc.,  a  Delaware   corporation   ("Prime"),   Prime/BDR
Acquisition,   L.L.C.,  a  Delaware  limited   liability  company  ("Newco  I"),
Prime/BDEC  Acquisition,  L.L.C., a Delaware limited  liability  company ("Newco
II"), BDEC, LASIK, Ronald W. Barnet,  M.D.  ("Barnet"),  David D. Dulaney,  M.D.
("Dulaney") and Mark Rosenberg  ("Rosenberg")  (PMSI,  Prime, Newco I, Newco II,
BDEC, LASIK,  Barnet,  Dulaney and Rosenberg are referred to herein individually
as a "Beneficiary" and collectively as "Beneficiaries").
                                                     RECITALS:
         WHEREAS,  the  Equity  Holder  is an equity  owning  member of BDEC and
LASIK.
         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Newco I, Newco II, Prime, PMSI, BDEC, LASIK,  Barnet,  Dulaney,  and
Rosenberg   are   consummating   that  certain   Contribution   Agreement   (the
"Contribution Agreement"), dated effective September 1, 1999.
         WHEREAS, in order to induce each of the Beneficiaries to consummate the
         transactions  contemplated by the  Contribution  Agreement,  the Equity
         Holder has agreed to certain  restrictions  on the activities of Equity
         Holder and his Affiliates (as hereinafter defined),  which restrictions
         the Equity Holder deems  reasonable  and  appropriate.  THEREFORE,  the
         parties hereto agree as follows:
                                                    AGREEMENTS:
         1. Confidentiality  Agreement.  Equity Holder acknowledges that through
his  relationship  with  BDEC  and  LASIK,  he will be  exposed  to  Proprietary
Information (as defined below) of Newco I, Newco II and/or each of their present
or future affiliates (which includes,  without  limitation,  BDEC, LASIK, Prime,
PMSI and each of their  present or future  affiliates)  (the party  owning  such
Proprietary   Information  is  referred  to  as  the  "Discloser"),   that  such
Proprietary  Information  is unique and valuable and that such  Discloser  would
suffer irreparable injury if its Proprietary  Information were divulged to those
in  competition  with  Discloser.   "Proprietary   Information"   shall  be  all
information  concerning  Discloser which Equity Holder acquires,  or to which he
has  access  through  his  relationship  with BDEC or  LASIK,  that has not been
publicly  disclosed  by  Discloser  or that is not a matter of common  knowledge
among  Discloser's  competitors,  including,  but not  limited  to,  information
relating to any  inventions,  processes,  software,  formulae,  plans,  devices,
compilations  of  information,   technical  data,   mailing  lists,   management
strategies, business distribution methods, names of suppliers (of both goods and
services)  and   customers,   names  of  employees  and  terms  of   employment,
arrangements  entered into with  suppliers  and  customers,  including,  but not
limited to, proposed expansion plans of Discloser,  marketing and other business
and pricing  strategies,  and trade  secrets of Discloser.  Notwithstanding  the
foregoing,  Proprietary  Information  shall not include  information or material
that would otherwise be Proprietary  Information if such information or material
is owned solely by BDEC and not  materially  used or relied on in the conduct of
the Business (as defined in the Contribution Agreement).
          Except with prior written approval of Discloser,  Equity Holder agrees
     that he will not, at any time after the Closing, as such term is defined in
     the  Contribution  Agreement:  (i)  directly or  indirectly,  disclose  any
     Proprietary  Information  to any person  except the  employees,  agents and
     consultants  of Newco I,  Newco II and/or  Discloser  who need to know such
     Proprietary  Information in connection with their relationship with Newco I
     or Newco II nor (ii) use Proprietary Information in any way, except for the
     purposes and benefit of Newco I or Newco II.
         Within  forty-eight  (48) hours of termination of his ownership of BDEC
and LASIK,  whether voluntary or involuntary,  Equity Holder will deliver to the
appropriate Discloser (without retaining copies thereof) all documents,  records
or other  memorializations  including copies of documents and any notes which he
has  prepared  that  contain   Proprietary   Information,   all  other  tangible
Proprietary  Information  in his  possession  or control and all of  Discloser's
credit cards, keys, equipment,  vehicles,  supplies and other materials that are
in his possession or under his control.
         2. Non-Competition Agreement. Equity Holder, hereby agrees that, at all
times during which the provisions of ARTICLE VIII of the Contribution  Agreement
are in effect,  and at all times until five (5) years after either LASIK and its
affiliates  (excluding PMSI,  Prime, and the subsidiaries of either of them), or
Prime and its affiliates  (excluding  LASIK),  no longer own any equity or other
interest in Newco I,  Equity  Holder will not  directly  or  indirectly,  either
through any kind of ownership  (other than ownership of securities of a publicly
held  corporation  of which he owns less than five  percent (5%) of any class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
advisor, consultant,  co-partner or in any individual or representative capacity
whatever,  either for his own  benefit or for the  benefit of any other  person,
corporation  or  other  entity,  without  the  prior  written  consent  of  each
Beneficiary,  commit any of the following  acts,  which acts shall be considered
violations of this covenant not to compete:
                  (a) Except through Newco I or its  subsidiaries,  or Newco II,
directly or indirectly engage in, or provide,  anywhere within a fifty (50) mile
radius of any center or facility that provides Refractive Surgery (as defined in
the Contribution  Agreement) and is owned, directly or indirectly,  partially or
wholly,  by Newco I or a subsidiary of Newco I  (collectively,  the  "Restricted
Area"),  any services (other than services included in the practice of medicine)
related to (i) the  operating of centers or facilities  that provide  Refractive
Surgery,  (ii) the  manufacture,  maintenance,  refurbishing,  repair,  sale, or
leasing of any equipment related to or necessary for the operating of centers or
facilities that provide  Refractive  Surgery,  or (iii) providing any management
services,  training  or  consulting  services  related to any of the  activities
described in (i) or (ii);
                  (b) Except through Newco I or its  subsidiaries,  or Newco II,
directly  or  indirectly  provide,  anywhere  within the  Restricted  Area,  (i)
facilities,  equipment  and  non-physician  personnel  for  the  performance  by
physicians of Refractive Surgery, (ii) the marketing,  scheduling and management
of Refractive  Surgery (but  excluding  marketing,  scheduling and management of
patients for treatment by Equity Holder), (iii) the credentialing and scheduling
of physicians to perform Refractive Surgery and (iv) the billing,  collecting or
accounting  for the  use of any  such  facilities,  equipment  or  non-physician
personnel;
          (c)  Directly  or  indirectly  request  or advise  any  person,  firm,
     physician,  corporation or other entity having a business relationship with
     Newco I or any of its subsidiaries,  Prime,  LASIK, BDEC, Barnet,  Dulaney,
     Rosenberg,  or any affiliate or related entity of any of them, to withdraw,
     curtail, or cancel its business with such person or entity; or

          (d) Directly or indirectly  hire any employee of Newco I or any of its
     subsidiaries,  Prime,  LASIK,  BDEC,  Barnet,  Dulaney,  Rosenberg,  or any
     affiliate  or  related  entity  of any of them,  or induce  or  attempt  to
     influence any employee of Newco I or any of its subsidiaries, Prime, LASIK,
     BDEC, Barnet,  Dulaney,  Rosenberg, or any such affiliate or related entity
     to  terminate  his or  her  employment  with  such  person  or  entity.

          3.  Exclusivity.  Equity Holder  acknowledges  that any acquisition or
     development of a Target Center (as defined in the  Contribution  Agreement)
     by Equity Holder through an entity not owned (wholly or partially, directly
     or  indirectly)  by Newco I shall be subject to the provisions of Section 2
     of this Agreement, regardless of whether such acquisition or development is
     contemplated  by or provided for in the  provisions  of ARTICLE VIII of the
     Contribution Agreement.
          4. Agreement.  Equity Holder has reviewed and carefully considered the
     provisions  of  Sections 1 and 2 of this  Agreement  and,  having  done so,
     agrees that the restrictions applicable to him as set forth therein (a) are
     fair and reasonable with respect to time,  geographic  area and scope,  (b)
     are not unduly  burdensome to him, and (c) are reasonably  required for the
     protection  of the  interests of the  Beneficiaries  for whose benefit such
     restrictions were agreed upon.
          5. Remedies.  Equity Holder agrees that a violation on his part of any
     applicable  covenant  contained in Sections 1 or 2 of this  Agreement  will
     cause the  Beneficiaries,  for whose benefit such  restrictions were agreed
     upon, irreparable damage for which remedies at law may be insufficient, and
     for that reason, he agrees that any of the Beneficiaries  shall be entitled
     as a matter of right to equitable remedies,  including specific performance
     and injunctive  relief,  therefor.  The right to specific  performance  and
     injunctive  relief shall be  cumulative  and in addition to whatever  other
     remedies,  at law or in equity, that the Beneficiaries may have, including,
     specifically, recovery of additional damages.
         6. Affiliates. For purposes of this Agreement, an "Affiliate" of Equity
Holder means any person married to, or any minor child of, Equity Holder and any
corporation, partnership or other entity that, at the date hereof or at any time
during the term hereof,  is controlled by, or under common control with,  Equity
Holder.  "Control" (and its derivatives),  in this context, means the possession
of,  directly or  indirectly,  the power to direct or cause the direction of the
management of the  applicable  corporation,  partnership  or other entity either
through the  ownership  of voting  securities  (or other equity  interests),  by
contract,  or by ownership of a membership  of a nonstock  corporation  or other
entity  enabling  Equity  Holder to elect one or more  members of the  governing
board of that nonstock corporation or other entity.
          7. Control of Affiliates' Actions.  Equity Holder will timely exercise
     all of his rights and powers to cause each of his Affiliates to comply with
     the terms of this Agreement. ------------------------------

          8. Indemnity.  Equity Holder agrees to indemnify, defend and hold each
     Beneficiary  harmless from and against any and all loss,  damage,  cost and
     expense  (including  attorneys'  fees) that may  result  from any breach or
     threatened  breach of this  Agreement by Equity  Holder or any Affiliate of
     Equity Holder. ---------

         9.       Miscellaneous.
          (a)  Amendments.  This Agreement may be modified or amended only by an
     instrument in writing executed by Equity Holder and each Beneficiary.
                  (b) Headings. The headings contained in this Agreement are for
                  reference  purposes  only and shall not  affect in any way the
                  meaning or  interpretation  of this  Agreement.  (c) Governing
                  Law.  This  Agreement  shall  be  construed  and  enforced  in
                  accordance  with the internal laws of the State of Texas,  and
                  not the conflicts of law provisions thereof.
          (d)  Parties  Bound.  This  Agreement  shall  be  binding  upon and be
     enforceable against the Equity Holder and Equity Holder's  Affiliates,  and
     their respective successors and representatives. This Agreement shall inure
     to the  benefit  of  each  Beneficiary  and  their  respective  successors,
     representatives and assigns. -------------
                  (e) Invalid  Provisions.  If any  provision of this  Agreement
(including, without limitation, any provision relating to the activities covered
by, or time period of, the covenants  contained in Section 2 of this  Agreement)
is held to be illegal,  invalid or  unenforceable  under  present or future laws
effective during the term hereof, such provision shall be fully severable;  this
Agreement  shall be  construed  and  enforced  as if such  illegal,  invalid  or
unenforceable  provision  had never  comprised a part hereof;  and the remaining
provisions  shall  remain in full force and effect and shall not be  affected by
the illegal,  invalid or unenforceable  provision or by its severance  herefrom.
Furthermore,  in lieu of such illegal, invalid or unenforceable provision, there
shall be added  automatically as a part of this Agreement a provision as similar
in terms to such illegal,  invalid or unenforceable provision as may be possible
and be legal, valid and enforceable.
          (f) Construction.  This Agreement shall be construed without regard to
     the  identity  of the person who drafted  the  various  provisions  of this
     Agreement. Each and every provision of this Agreement shall be construed as
     though all of the  parties  participated  equally in the  drafting  of this
     Agreement.  Consequently,  Equity Holder  acknowledges  and agrees that any
     rule  of  construction  that a  document  is to be  construed  against  the
     drafting party shall not be applicable to this Agreement. ------------

          (g) Defined Terms. Any capitalized terms not otherwise defined in this
     Agreement  shall  have the same  meaning  as set forth in the  Contribution
     Agreement. -------------
                                             [Signature page follows]



<PAGE>
                                                 SIGNATURE PAGE TO
                                             NON-COMPETITION AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:                                      /s/ Robert B. Pinkert, O.D.
                                                    Robert B. Pinkert, O.D.





<PAGE>



                                 PROMISSORY NOTE
Austin, Texas                    (LINE OF CREDIT)             September 1, 1999



PROMISE TO PAY: For value  received,  the undersigned  Borrower  (whether one or
more) promises to pay to the order of Lender the Principal Amount, to the extent
advanced by Lender, together with interest on the unpaid balance of such amount,
in lawful  money of the United  States of America,  in  accordance  with all the
terms, conditions,  and covenants of this Note and the Loan Documents identified
below.

     BORROWER:  Prime/BDR  Acquisition,  L.L.C.,  a Delaware  limited  liability
company
     BORROWER'S ADDRESS FOR NOTICE:  1301 Capital of Texas Highway,  Suite C-300
Austin, Texas 78746 Attention: President
LENDER:           Prime Medical Operating, Inc., a Delaware corporation

     LENDER'S ADDRESS FOR PAYMENT:  1301 Capital of Texas Highway,  Suite C-300,
Austin, Texas 78746 Attention: Chief Financial Officer
PRINCIPAL AMOUNT:  Two Hundred Thousand Dollars ($200,000)

INTEREST RATE:  Fifteen Percent (15%)

PAYMENT  TERMS:  Interest on the unpaid  balance of this Note is due and payable
quarterly,  beginning  November 1, 1999, and continuing  regularly and quarterly
thereafter on or before the first day of February,  May, August, until September
1, 2000 (the "Maturity  Date"),  when the outstanding  principal balance and all
accrued  interest shall be due and payable in full.  Interest will be calculated
on the unpaid  principal  balance.  Each payment  will be credited  first to the
accrued interest and then to the reduction of principal.

REVOLVING  LINE OF  CREDIT:  This Note  evidences  a  revolving  line of credit.
Subject to the terms of the Loan Agreement  between  Borrower and Lender of even
date  herewith,  all or any portion of the Principal  Amount of this Note may be
borrowed, paid, prepaid, repaid, and reborrowed,  from time to time prior to the
Maturity  Date and in accordance  with the Loan  Documents.  Each  borrowing and
repayment  hereunder will be (i) endorsed on an attachment to this Note, or (ii)
entered  in the books and  records of  Lender.  The books and  records of Lender
shall be prima facie  evidence  of all sums due  Lender.  If an event of default
exists  under  this Note or any Loan  Document,  then  Lender  shall be under no
obligation to make any advance under this Note.

     LOAN  AGREEMENT:  This Note is executed  pursuant to and is governed by the
terms of the Loan  Agreement  of even date  herewith,  executed by Borrower  and
Lender, as amended (collectively, the "Loan Agreement").
1.       INTEREST PROVISIONS:

Rate:  The  principal  balance of this Note from time to time  remaining  unpaid
prior to maturity  shall bear  interest at the  Interest  Rate per annum  stated
above.  Interest  shall be  calculated  on the  amount  of each  advance  of the
Principal Amount of this Note from the date of each such advance.

Maximum  Lawful Interest:  The term "Maximum Lawful Rate" means the maximum rate
         of interest  and the term  "Maximum  Lawful  Amount"  means the maximum
         amount  of  interest  that is  permissible  under  applicable  state or
         federal law for the type of loan  evidenced  by this Note and the other
         Loan  Documents.  If the Maximum Lawful Rate is increased by statute or
         other governmental action subsequent to the date of this Note, then the
         new  Maximum  Lawful  Rate  shall be  applicable  to this Note from the
         effective date thereof, unless otherwise prohibited by applicable law.

Spreadingof Interest:  Because of the possibility of irregular periodic balances
         of principal or premature payment,  the total interest that will accrue
         under this Note cannot be determined in advance. Lender does not intend
         to contract for,  charge,  or receive more than the Maximum Lawful Rate
         or Maximum Lawful Amount  permitted by applicable state or federal law,
         and to prevent such an  occurrence  Lender and Borrower  agree that all
         amounts of interest,  whenever  contracted for, charged, or received by
         Lender, with respect to the loan of money evidenced by this Note, shall
         be spread,  prorated,  or  allocated  over the full period of time this
         Note is unpaid,  including  the period of any renewal or  extension  of
         this Note.  If demand for payment of this Note is made by Lender  prior
         to the full stated term, the total amount of interest  contracted  for,
         charged,  or  received  to the time of such  demand  shall  be  spread,
         prorated, or allocated along with any interest thereafter accruing over
         the full period of time that this Note  thereafter  remains  unpaid for
         the purpose of determining if such interest  exceeds the Maximum Lawful
         Amount.

Excess   Interest:  At maturity  (whether by  acceleration  or  otherwise) or on
         earlier  final  payment of this Note,  Lender  shall  compute the total
         amount of interest that has been contracted for,  charged,  or received
         by Lender or  payable by  Borrower  under  this Note and  compare  such
         amount to the Maximum  Lawful  Amount  that could have been  contracted
         for, charged, or received by Lender. If such computation  reflects that
         the total amount of interest that has been contracted for, charged,  or
         received  by Lender or payable by Borrower  exceeds the Maximum  Lawful
         Amount,  then Lender  shall apply such excess to the  reduction  of the
         principal balance and not to the payment of interest; or if such excess
         interest  exceeds the unpaid  principal  balance,  such excess shall be
         refunded to Borrower. This provision concerning the crediting or refund
         of excess  interest  shall control and take  precedence  over all other
         agreements  between  Borrower and Lender so that under no circumstances
         shall the total interest contracted for, charged, or received by Lender
         exceed the Maximum Lawful Amount.

Interest After Default:  At Lender's option,  the unpaid principal balance shall
         bear interest after maturity  (whether by acceleration or otherwise) at
         the "Default  Interest  Rate." The Default  Interest  Rate shall be, at
         Lender's  option,  (i) the Maximum  Lawful Rate, if such Maximum Lawful
         Rate is established by applicable law; or (ii) the Interest Rate stated
         on the first page of this Note plus five (5) percentage  points,  if no
         Maximum Lawful Rate is established by applicable law; or (iii) eighteen
         percent (18%) per annum; or (iv) such lesser rate of interest as Lender
         in its sole  discretion  may choose to charge;  but never more than the
         Maximum  Lawful Rate or at a rate that would  cause the total  interest
         contracted  for,  charged,  or received by Lender to exceed the Maximum
         Lawful Amount.

Daily Computation of Interest: To the extent permitted by applicable law, Lender
at its option will  calculate  the per diem interest rate or amount based on the
actual  number of days in the year (365 or 366, as the case may be),  and charge
that per diem interest rate or amount each day. In no event shall Lender compute
the interest in a manner that would cause  Lender to contract  for,  charge,  or
receive interest that would exceed the Maximum Lawful Rate or the Maximum Lawful
Amount

DEFAULT PROVISIONS:

EVENTS OF DEFAULT AND  ACCELERATION  OF MATURITY:  LENDER MAY, AFTER THIRTY (30)
DAYS'  WRITTEN  NOTICE TO BORROWER  AND  BORROWER'S  FAILURE TO CURE WITHIN SUCH
30-DAY  PERIOD  AND  WITHOUT  FURTHER  NOTICE OR DEMAND,  (except  as  otherwise
required  by  statute),  ACCELERATE  THE  MATURITY  OF THIS NOTE AND DECLARE THE
ENTIRE UNPAID PRINCIPAL BALANCE AND ALL ACCRUED INTEREST AT ONCE DUE AND PAYABLE
IF:

         There is  default  in the  payment  of any  installment  of  principal,
interest,  or any other sum  required to be paid under the terms of this Note or
any of the Loan Documents; or

         There is a breach or  default  (other  than by Lender or Prime  Medical
Services,  Inc.)  under this Note or any of the Loan  Documents,  including  any
instrument  securing the payment of this Note or any loan agreement  relating to
the advance of loan proceeds.

WAIVER   BY  BORROWER:  EXCEPT AS PROVIDED IN  PARAGRAPH  2(a) HEREOF AND IN ANY
         OTHER LOAN  DOCUMENT,  BORROWER AND ALL OTHER  PARTIES  LIABLE FOR THIS
         NOTE  WAIVE,  DEMAND,  NOTICE  OF  INTENT TO  DEMAND,  PRESENTMENT  FOR
         PAYMENT,  NOTICE OF  NONPAYMENT,  PROTEST,  NOTICE OF  PROTEST,  GRACE,
         NOTICE OF DISHONOR,  NOTICE OF INTENT TO ACCELERATE MATURITY, NOTICE OF
         ACCELERATION  OF MATURITY,  AND  DILIGENCE IN  COLLECTION.  EACH MAKER,
         SURETY,  ENDORSER,  AND GUARANTOR OF THIS NOTE WAIVES AND AGREES TO ONE
         OR MORE  EXTENSIONS  FOR ANY PERIOD OR PERIODS OF TIME, AND ANY PARTIAL
         PAYMENTS, BEFORE OR AFTER MATURITY,  WITHOUT PREJUDICE TO THE HOLDER OF
         THIS NOTE. EACH MAKER, SURETY, ENDORSER, AND GUARANTOR WAIVES NOTICE OF
         ANY AND ALL RENEWALS, EXTENSIONS,  REARRANGEMENTS, AND MODIFICATIONS OF
         THIS NOTE.

Non-Waiver by Lender:  Any previous extension of time,  forbearance,  failure to
pursue some  remedy,  acceptance  of late  payments,  or  acceptance  of partial
payment by Lender,  before or after  maturity,  does not  constitute a waiver by
Lender of its subsequent  right to strictly  enforce the collection of this Note
according to its terms.

Other  Remedies Not  Required:  Lender shall not be required to first file suit,
exhaust all  remedies,  or enforce its rights  against any  security in order to
enforce payment of this Note.

Joint and Several  Liability:  Each Borrower who signs this Note, and all of the
other  parties  liable  for the  payment  of  this  Note,  such  as  guarantors,
endorsers,  and sureties,  are jointly and  severally  liable for the payment of
this Note.

Attorney's  Fees: If Lender  requires the services of an attorney to enforce the
payment of this Note or the performance of the other Loan Documents,  or if this
Note is collected through any lawsuit,  probate,  bankruptcy,  or other judicial
proceeding,  Borrower  agrees to pay  Lender an amount  equal to its  reasonable
attorney's fees and other collection  costs.  This provision shall be limited by
any applicable statutory  restrictions  relating to the collection of attorney's
fees.

3.       MISCELLANEOUS PROVISIONS:

Subsequent Holder: All references to Lender in this Note shall also refer to any
subsequent owner or holder of this Note by transfer, assignment, endorsement, or
otherwise.

Transfer:Borrower  acknowledges and agrees that Lender may transfer this Note or
         partial   interests  in  the  Note  to  one  or  more   transferees  or
         participants,  including without  limitation  transfers provided for in
         Section  8.10 of the Loan  Agreement.  Borrower  authorizes  Lender  to
         disseminate  to any  such  transferee  or  participant  or  prospective
         transferee or participant any information it has pertaining to the loan
         evidenced  by  this  Note,   including,   without  limitation,   credit
         information  on Borrower and any  guarantor of this Note and any of the
         type of information described in Section 8.10 of the Loan Agreement.

Other  Parties  Liable:  All  promises,  waivers,   agreements,  and  conditions
applicable  to Borrower  shall  likewise be  applicable  to and binding upon any
other  parties  primarily  or  secondarily  liable for the payment of this Note,
including all guarantors, endorsers, and sureties.

Successors  and Assigns:  The  provisions of this Note shall be binding upon and
for the benefit of the successors, assigns, heirs, executors, and administrators
of Lender and Borrower.

No Duty or Special  Relationship:  Borrower acknowledges that Lender has no duty
of good faith to Borrower,  and Borrower acknowledges that no fiduciary,  trust,
or other special relationship exists between Lender and Borrower.

Modifications:  Any modifications agreed to by Lender relating to the release of
liability of any of the parties primarily or secondarily  liable for the payment
of this Note, or relating to the release,  substitution, or subordination of all
or part of the security for this Note,  shall in no way  constitute a release of
liability  with  respect to the other  parties or  security  not covered by such
modification.

Entire  Agreement:  Borrower  warrants and  represents  that the Loan  Documents
constitute the entire agreement  between Borrower and Lender with respect to the
loan  evidenced  by this Note and agrees  that no  modification,  amendment,  or
additional  agreement  with  respect  to such loan or the  advancement  of funds
thereunder will be valid and  enforceable  unless made in writing signed by both
Borrower and Lender.

Borrower's  Address  for Notice:  All  notices  required to be sent by Lender to
Borrower shall be sent by U.S. Mail, postage prepaid,  to Borrower's Address for
Notice stated on the first page of this Note, until Lender shall receive written
notification from Borrower of a new address for notice.

Lender's  Address for  Payment:  All sums payable by Borrower to Lender shall be
paid at Lender's  Address for Payment  stated on the first page of this Note, or
at such other address as Lender shall designate from time to time.

Business Use:  Borrower  warrants and  represents to Lender that the proceeds of
this Note will be used solely for business or commercial purposes, and in no way
will the proceeds be used for personal, family, or household purposes.

Chapter 15 Not Applicable:  It is understood that Chapter 15 of the Texas Credit
Code relating to certain  revolving credit loan accounts and tri-party  accounts
is not applicable to this Note.

APPLICABLE  LAW: THIS NOTE HAS BEEN EXECUTED AND DELIVERED IN TEXAS AND SHALL BE
CONSTRUED IN ACCORDANCE  WITH THE APPLICABLE  LAWS OF THE STATE OF TEXAS AND THE
LAWS OF THE UNITED STATES OF AMERICA APPLICABLE TO TRANSACTIONS IN TEXAS.

4.       LOAN DOCUMENTS:

This Note.

The Loan Agreement and the Loan Documents as defined therein.

All      other  documents  signed in connection  with the Loan  Agreement or the
         loan  evidenced  by this  Note,  including,  without  limitation,  that
         certain  Contribution  Agreement,  dated  effective  September 1, 1999,
         between and among Borrower,  Lender,  Prime Medical  Services,  Inc., a
         Delaware  corporation,   Prime/BDEC  Acquisition,  L.L.C.,  a  Delaware
         limited  liability  company,  Barnet Dulaney Eye Center,  P.L.L.C.,  an
         Arizona  professional  limited  liability  company,   LASIK  Investors,
         L.L.C., a Delaware limited liability company,  David D. Dulaney,  M.D.,
         Ronald  W.  Barnet,   M.D.,  and  Mark  Rosenberg  (the   "Contribution
         Agreement") and each  Transaction  Document (as such term is defined in
         the Contribution Agreement).

                                              [Signature page follows]



<PAGE>


                                                  SIGNATURE PAGE TO
                                                   PROMISSORY NOTE


EXECUTED this 1 day of September, 1999.



                 BORROWER:

             PRIME/BDR ACQUISITION, L.L.C., a Delaware limited liability company



                                  By: /s/ Ronald W. Barnet, M.D.

                                  Printed Name: Ronald W. Barnet, M.D.

                                  Title: Manager



<PAGE>



                              COLLOCATION AGREEMENT

                                 BY AND BETWEEN

                       BARNET DULANEY EYE CENTER, P.L.L.C.

                                       AND

                         PRIME/BDEC ACQUISITION, L.L.C.






<PAGE>


                                   COLLOCATION
                                    AGREEMENT

     This COLLOCATION  AGREEMENT  ("Agreement"),  effective as of the 1st day of
September,  1999 (the  "Effective  Time"),  is by and between BARNET DULANEY EYE
CENTER,  P.L.L.C.,  an Arizona  professional limited liability company ("BDEC"),
and  PRIME/BDEC  ACQUISITION,  L.L.C.,  a  Delaware  limited  liability  company
("Company").

                                               W I T N E S S E T H:

     WHEREAS,  the  Company  has been  organized  for the  purpose of  providing
facilities,  equipment  and  non-physician  personnel  for  the  performance  by
physicians  of  Refractive  Surgery  (as  defined  herein),  for the  marketing,
scheduling  and  management of Refractive  Surgery,  for the  credentialing  and
scheduling  of  physicians  to perform  Refractive  Surgery and for the billing,
collecting  and   accounting  for  the  use  of  the  facility,   equipment  and
non-physician personnel (the "Business");

     WHEREAS,  BDEC has owned or leased assets for the performance by physicians
of Refractive Surgery, including, without limitation, certain space located in a
building at 4800 North 22nd Street,  Phoenix,  Arizona  85016 and certain  space
located in a building at 555 East River Road,  Tucson,  Arizona  (individually a
"Facility"  and  collectively  the  "Facilities")  and in  connection  with each
Facility, equipment,  instruments, computer software used in connection with the
equipment, certain leases and contracts, the leasehold improvements,  furniture,
fixtures and other fixed assets and items of personal property used primarily in
or  materially  relied  on  for  the  performance  of  Refractive  Surgery  (the
"Equipment and Personalty");

     WHEREAS, BDEC employs  non-physician  personnel (the "BDEC Employees") with
expertise  and  experience  in  assisting   physicians  in  the  performance  of
Refractive  Surgery,   in  credentialing  and  scheduling   physicians  for  the
performance  of  Refractive  Surgery  in  the  Facilities,   in  performing  the
scheduling of patients for Refractive  Surgery in the Facilities,  in performing
marketing,  accounting,  billing  and  collection  services  for  the use of the
Facilities  and in managing  the  Facilities  and all  non-physician  aspects of
Refractive Surgery in the Facilities (the "Support Services");

     WHEREAS,   BDEC  employs  physician  and   non-physician   executives  (the
"Managers")  with expertise and experience in the management of the  Facilities,
the Equipment and Personalty,  the Support  Services and all other elements of a
Refractive Surgery center (the "Management Services");

     WHEREAS,  BDEC, Prime Medical  Operating,  Inc.("Prime") and others entered
into that certain Contribution  Agreement dated effective September 1, 1999 (the
"Contribution  Agreement"),  pursuant  to  which  Prime,  BDEC and  others  have
participated in a series of transactions that were completed simultaneously with
the execution and delivery of this Agreement,  in which transactions the Company
became the owner of the  Equipment  and  Personalty  and the business  conducted
therewith,  excluding the practice of medicine,  and in which  transactions BDEC
agreed to provide to the Company the  Facility and the  Management  Services and
Support Services on the terms and conditions set forth in this Agreement;

     NOW, THEREFORE,  for and in consideration of the mutual covenants set forth
herein, and other good and valuable  consideration,  the receipt and adequacy of
which are hereby forever acknowledged and confessed, the parties hereto agree as
follows:

                                                     ARTICLE I
                                                    DEFINITIONS

     1.1 Agreement shall mean this Collocation Agreement between the Company and
BDEC  and  any  amendments  hereto  as may  from  time to  time  be  adopted  as
hereinafter provided.

     1.2 BDEC shall mean Barnet Dulaney Eye Center, P.L.L.C.

     1.3 Buildings shall mean Building P and Building T.

     1.4 Building P shall mean the  building  located at 4800 North 22nd Street,
Phoenix, Arizona 85016, and known generally as the Barnet Dulaney Eye Center.

     1.5  Building T shall  mean the  building  located at 555 East River  Road,
Tucson, Arizona, and known generally as the Barnet Dulaney Eye Center.

     1.6  Business  shall  mean  the  provision  of  facilities,  equipment  and
non-physician  personnel for the performance by physicians of Refractive Surgery
(as defined  herein),  the  marketing,  scheduling  and management of Refractive
Surgery,  the credentialing  and scheduling of physicians to perform  Refractive
Surgery and the billing,  collecting and accounting for the use of the facility,
equipment and non-physician personnel.

         1.7 Business  Expense shall mean all  out-of-pocket  costs and expenses
incurred by BDEC solely and  exclusively  in the  performance  of its duties and
obligations  under,  and in accordance  with, this Agreement.  Business  Expense
shall also  include  that portion  (allocated  based on the relative  percentage
amount of each such  employee's  time spent working  directly on the Business of
the Company) of salaries,  wages and  benefits for those  personnel  employed by
BDEC to provide  services  hereunder,  but only to the extent such employees (i)
work  directly on the  Business  of the  Company  and (ii) are either  listed on
Exhibit B hereto or are  subsequently  employed to replace such listed employees
or are  added  in the  same  service  categories  related  to  the  Business  as
corresponds  to the service  categories  applicable to the  employees  listed on
Exhibit B. Business  Expense  shall also include a reasonable  allocation of the
out-of-pocket   costs  incurred  by  BDEC  related  to  hiring  such  personnel.
Notwithstanding the foregoing, Business Expense shall not include any portion of
the salaries,  wages or benefits related to any personnel  employed or otherwise
retained or contracted by BDEC who work in any of the following  departments  or
fall  within any of the  following  categories:  (a)  accounting,  (b)  accounts
receivable,  (c) purchasing, (d) practice operations, (e) management information
systems and facilities support, (f) human resources,  (g) credentialing,  or (h)
executive management.  Furthermore,  Business Expense shall not include any rent
or other costs or expenses  incurred by BDEC  pursuant to the Base  Leases.  For
illustration  purposes,  the parties agree that Business Expense for the Phoenix
Refractive  Surgery  center  based on the pro forma  annualized  facility  model
attached  hereto  as  Exhibit  A for the  first  full  year of the  Term of this
Agreement  would be  $1,663,638,  being the sum of the  categories  on Exhibit A
marked  with an  asterisk.  It is the  intention  of the parties  that  Business
Expense be consistent with the methodology reflected in Exhibit A.

     1.8 Company shall mean Prime/BDEC Acquisition, L.L.C.

     1.9  Facility  and  Facilities  shall have the  meaning  given to it in the
recitals to this Agreement.

     1.10 Premises P shall mean the Facility and other space located in Building
P to which the right to use is granted in Section 2.3 hereof.

     1.11 Premises T shall mean the Facility and other space located in Building
T to which the right to use is granted in Section 2.3 hereof.

     1.12 Refractive Surgery shall mean, collectively, any current and/or future
surgical procedures intended to correct myopia,  hyperopia or astigmatism of the
eye, excluding procedures aimed only at restoring accommodation (presbyopia) and
procedures  to  treat  only  cataracts,   glaucoma,   oculoplastics  or  retinal
abnormality.

     1.13 Services Fee shall mean BDEC's compensation  established and described
in Article VI hereof.

     1.14 State shall mean the State of Arizona.

     1.15 Term shall mean the  initial  and any  renewal  periods of duration of
this Agreement as described herein.

                                   ARTICLE II
                            RIGHT TO USE THE PREMISES

     2.1 Base Lease.  Section 2.3  contains a grant of a right to use Premises P
and Premises T and is subject and  subordinate  to the terms and  conditions  of
those certain  leases as amended ("Base  Leases")  pursuant to which BDEC leases
the Building P and Building T.

     2.2 Users of  Buildings.  Building P and  Building T are used for  multiple
activities, including, but not limited to, Refractive Surgery, office and clinic
activities of BDEC  physicians and other  professionals,  an ambulatory  surgery
center ("ASC") and marketing,  accounting,  management and other  administrative
activities.  The various  activities  in each Building do not  necessarily  have
specific or identified space and, in some instances, more than one activity uses
a space at the same time or at different times.  BDEC designates,  schedules and
modifies  the  location  and the times that each  activity  can use space in the
Buildings.

         2.3 Grant of Right to Use. In  consideration  of  Company's  payment to
BDEC of the Purchase Price, as defined in the Contribution Agreement, and on the
terms and  conditions of this  Agreement,  BDEC hereby grants to the Company the
non-exclusive  right to use for  Refractive  Surgery the spaces in the Buildings
where the  Equipment  and  Personalty  are located at the times  during  regular
business  hours and in the manner  designated by BDEC (but in no event less than
forty percent (40%) of the of the business hours during each week),  which might
require the using of such space while the same or adjoining  space is being used
by an ASC or on a  cooperative  schedule  with an ASC.  BDEC also  grants to the
Company the non-exclusive  right to use and to permit its guests and invitees to
use the common areas in accordance  with the Base Leases.  Notwithstanding  that
the foregoing grants are  non-exclusive,  BDEC covenants and agrees that it will
not allow any person or entity,  other than the Company, to utilize any space in
the  Buildings,  any Equipment and Personalty or any BDEC Employees for purposes
of conducting any component of the Business.

     2.4 Term and Conditions of Grant. The grants set forth in Section 2.3 above
are each for the term and on the conditions, requirements,  covenants, rules and
regulations  of the Base Leases and subject to  Company's  paying its  allocated
portion of the rent,  common area  charges and other  payments  required of BDEC
under the Base Leases.

     2.5 Maintenance of Base Leases. Throughout the Term of this Agreement, BDEC
covenants  and agrees to  maintain  all Base  Leases in full  force and  affect,
without any breach or default by BDEC thereunder.

                                                    ARTICLE III
                                         APPOINTMENT AND AUTHORITY OF BDEC

     3.1 Appointment. The Company hereby appoints BDEC as its sole and exclusive
agent  for the  management  and  performance  of  day-to-day  operations  of the
Business in the  Facilities,  using the  Equipment and  Personalty,  through the
provision of Management  Services and Support Services,  as defined herein,  and
BDEC hereby accepts such appointment,  subject at all times to the provisions of
this Agreement.

         3.2  Authority.  Consistent  with  the  provisions  of this  Agreement,
directions given by the Company and operating and capital budgets established by
the Company,  BDEC shall have the responsibility  and commensurate  authority to
provide,  or  cause  to be  provided,  personnel,  business  and  administrative
services  for the  Company,  which shall  include  those  services  set forth in
Article  III hereof.  BDEC is hereby  expressly  authorized  to provide all such
services  in  whatever  manner  BDEC,  in  good  faith,  deems  appropriate  and
consistent  with  commercially  reasonable  standards  to  meet  the  day-to-day
requirements  of  the  business  functions  of the  Company  or  related  to the
Business.  The  authority  of BDEC  shall  extend no further  than is  expressly
provided  herein,  and  shall  not be  extended  by  implication  or  otherwise.
Notwithstanding  anything  contained herein to the contrary,  BDEC shall have no
authority  to speak on behalf of, or to bind,  the Company  with  respect to any
third party.

     3.3 Retained Authority.  The Company shall at all times retain the ultimate
responsibility  for the  operation of the Business  and,  except as delegated to
BDEC herein or by resolution of Company's  managers,  shall retain the authority
and power and to make all decisions with respect to its assets and rights.

     3.4  Nature of  Relationship.  The  parties  acknowledge  and agree that no
partnership  or other form of entity,  or any joint and  several  liability,  is
intended to be created by or between them by the  execution or operation of this
Agreement, and none of the foregoing should be implied.

                                                    ARTICLE IV
                                                 COVENANTS OF BDEC

     4.1  Management  and Support  Services.  BDEC shall provide the  Management
Services  and  Support  Services  necessary  to operate  the  Business as it was
operated by BDEC prior to the Effective Time, including,  but not limited to the
following:

     4.1.1 Marketing and Scheduling.  BDEC shall conduct  marketing  efforts for
the Facility and shall schedule patient treatment in the Facility, in the manner
that such services were performed prior to the Effective Time.

     4.1.2  Physician  Matters.  BDEC  shall  credential  physicians  to perform
Refractive  Surgery in the Facility  and shall  schedule  physicians  to use the
Facility in the manner that such services were performed  prior to the Effective
Time.

     4.1.3 Supplies.  As agent for the Company, BDEC shall obtain all reasonable
medical,  office, and other supplies,  including stationery and forms, and shall
ensure that the Company is at all times adequately stocked with such supplies as
are reasonably necessary and appropriate for the operation of the Business.

     4.1.4  Licenses and Permits.  BDEC shall  coordinate  all  development  and
planning  processes,  and apply for and use  BDEC's  best  efforts to obtain and
maintain all federal,  state, and local licenses and regulatory permits required
for or in connection with the operation of the Business.

     4.1.5 Contract  Negotiations.  BDEC shall negotiate,  either directly or on
the Company's  behalf, as appropriate,  all contractual  arrangements with third
parties as are reasonably necessary and appropriate for the Business.

     4.1.6 Financial  Matters.  BDEC shall  establish and administer  accounting
procedures,  controls,  and  systems  for  the  development,   preparation,  and
safekeeping  of records and books of accounts  relating to the  Company,  all of
which shall be prepared and  maintained in accordance  with  generally  accepted
accounting  principles  consistently  applied. BDEC shall prepare and deliver to
the Company,  and each of its members,  within thirty (30) days after the end of
each fiscal year of the Company,  a balance sheet, a profit and loss  statement,
and a  statement  of sources  and  applications  of funds and changes in working
capital reflecting the financial status of the Company and as of the end of such
prior fiscal year,  all of which shall be prepared in accordance  with generally
accepted accounting principles  consistently applied.  Additionally,  BDEC shall
prepare and deliver to the board of  managers  of the  Company,  and each of the
Company's members,  monthly financial  statements within ten (10) days after the
end of each month, and shall prepare and deliver to the board of managers of the
Company,  and each of the Company's members,  such other financial statements or
records  as BDEC may  from  time to time  deem  appropriate  or as the  board of
managers of the Company,  or its members,  may reasonably  request. On or before
ninety (90) days prior to the end of each fiscal year of the Company,  BDEC will
prepare and deliver to the board of  managers  of the  Company,  and each of the
Company's  members,  a  proposed  operating  budget of  projected  expenses  and
revenues  of  the  Company  for  the  next  fiscal  year  of  the  Company,  and
representatives of BDEC shall make themselves  reasonably available to the board
of managers and the members of the Company to explain such  proposed  budget and
the underlying assumptions.

     4.1.7 Billing and Collection.  BDEC shall be solely responsible for billing
and  collecting  for all  services  provided  by Company  and for the use of the
Facility and Equipment and  Personalty.  Company shall be entitled to all monies
collected by BDEC on behalf of Company.

     4.1.8 Information Systems.  BDEC shall provide and maintain the information
systems it deems  necessary to operate the Business.  BDEC shall have reasonable
discretion to select hardware and software,  provided such hardware and software
shall be adequate to operate the Business in a commercially  reasonable  manner,
and BDEC  shall be  responsible  for  training  employees  to  operate  any such
systems.

     4.1.9 Legal  Actions.  As requested  by the Company,  BDEC shall advise and
assist the Company in instituting  or defending  legal actions or proceedings by
or  against  third  parties  arising  out of the  Business,  including,  without
limitation,  those actions necessary for the protection and continued  operation
of the Company.  BDEC shall have no authority to initiate,  compromise or settle
any legal  action in the name of the  Company,  or to confess a judgment  in the
name of, or on behalf of, the Company.

     4.1.10  Insurance.  (a) BDEC shall  obtain and  maintain  professional  and
comprehensive  general liability  insurance and other insurance covering Company
for the  risks  and in the  amounts  typically  carried  by  others  in the same
business as Company.

     (b) BDEC  shall  obtain  and  maintain  appropriate  workers'  compensation
coverage for BDEC's  personnel and shall carry  professional  and  comprehensive
general  liability  insurance  covering all BDEC  personnel in amounts that BDEC
deems necessary, the cost of which insurance shall be a Business Expense.

         4.2  Personnel.  BDEC shall  employ or otherwise  retain,  and shall be
responsible  for  interviewing,   selecting,   hiring,  training,   supervising,
scheduling,  and terminating,  non-physician  personnel as BDEC deems reasonably
necessary and appropriate for the performance of Management Services and Support
Services.  Such personnel may include  temporary or "floater"  personnel who are
retained by BDEC to  substitute  for permanent  personnel.  BDEC shall have sole
responsibility  for determining the salaries,  wages, and fringe benefits of all
such  personnel,  for paying such  salaries and wages,  and for  providing  such
fringe benefits,  and for  withholding,  as required by law, any sums for income
tax, unemployment insurance,  social security, or any other withholding required
by applicable law or governmental  requirement.  BDEC shall have sole discretion
in decisions  regarding the termination of personnel employed by BDEC to provide
services  to the  Company.  BDEC shall  indemnify  the  Company and the Compan s
managers and members and hold them  harmless from and against any claim or cause
of action  which  alleges  or is based upon any act or  omission  by BDEC or its
owners, managers,  directors, officers or employees with respect to any employee
or  former  employee  of BDEC.  This  indemnity  obligation  shall  survive  any
termination or expiration of this Agreement.

     4.2.1  Non-Exclusivity.  In  recognition  of the fact  that  the  personnel
retained by BDEC to provide services pursuant to this Agreement may from time to
time perform  services for others,  this  Agreement  shall not prevent BDEC from
performing  such services for others or restrict BDEC from using such  personnel
in the  performance  of  services  for other  parties  which are not in the same
business as Company.

                  4.2.2 Equal Employment Opportunity.  Without limitation of any
provision set forth herein,  BDEC expressly agrees,  for itself and on behalf of
the  Company,  to abide by any and all  applicable  federal  and/or  State equal
employment  opportunity  statutes,  rules, and regulations,  including,  without
limitation,  Title VII of the Civil  Rights  Act of 1964,  the Equal  Employment
Opportunity Act of 1972, the Age  Discrimination  in Employment Act of 1967, the
Equal  Pay Act of 1963,  the  National  Labor  Relations  Act,  the  Fair  Labor
Standards  Act, the  Rehabilitation  Act of 1973,  the  Occupational  Safety and
Health Act of 1970,  and the Americans  with  Disabilities  Act, all as may from
time-to-time be modified or amended.

     4.2.3  Labor  Reports.  BDEC shall for its own  account or on behalf of the
Company, as appropriate,  prepare,  maintain, and file all requisite reports and
statements  regarding income tax withholdings,  unemployment  insurance,  social
security, workers' compensation,  equal employment opportunity, or other reports
and statements  required with respect to personnel  provided by BDEC pursuant to
this Agreement and with respect to all personnel  employed or otherwise retained
by the Company.

     4.3 Conduct of Business.  BDEC  represents and warrants to the Company that
it is  authorized  to enter  into and  perform  this  Agreement  and its  duties
hereunder  without the consent or approval of any third party which has not been
obtained.  BDEC covenants and agrees to provide all of the services  required of
it hereunder, and to perform all of its obligations hereunder, in a commercially
reasonable  manner  and  in  compliance  with  all  applicable  laws  and  legal
requirements.

                                                   ARTICLE V
                                              COVENANTS OF COMPANY

     5.1 Notices to BDEC.  Company will give BDEC timely notice of operating and
capital  budgets  approved by the Company and directions or requests that it has
with respect to the conduct of the Business or the manner in which BDEC performs
its duties hereunder in order that BDEC shall have an opportunity to comply with
such budgets, directions or requests.

     5.2 Invoices and  Payment.  BDEC shall  deliver to the board of managers of
the Company, and to each of the members of the Company, monthly invoices setting
forth the Services  Fee, Use Fees,  and expense  reimbursement  due BDEC for the
immediately  preceding  month,  together with such supporting  documentation  as
shall be reasonably necessary to document the calculation and incurrence of such
amounts in accordance with the terms of this Agreement. The Company will pay, or
authorize BDEC in writing to pay, the invoiced  amounts  properly due within ten
(10)  days  after  receipt  of such  invoice,  unless  any of such  amounts  are
contested in good faith.

                                                   ARTICLE VI
                                             FINANCIAL ARRANGEMENT

     6.1 Amount of Services Fee. As  compensation  (the "Services  Fee") for the
Management Services and Support Services to be rendered hereunder, BDEC shall be
entitled to receive  from the Company an amount equal to Two percent (2%) of the
Company's Net Revenues (as hereinafter defined).

         6.2  Determination  of Net Revenues.  For purposes of Section 6.1, "Net
Revenues" shall mean the total operating  revenues of the Company net of revenue
deductions  which  include  without  limitation  an  allowance  for  contractual
allowances,  discounts,  professional fees, co-management fees and staff managed
fees and other uncollectible  amounts,  all as determined in accordance with the
methodology  used in the  preparation  of  Exhibit  A hereto  and  otherwise  in
accordance with generally accepted accounting  principles  consistently applied.
For illustration  purposes,  the parties agree that Net Revenues for the Phoenix
Refractive  Surgery  center  based on the pro forma  annualized  facility  model
attached  hereto  as  Exhibit  A for the  first  full  year of the  Term of this
Agreement would be $5,968,627.

     6.3 Business Expenses. In addition to the Services Fee described in Section
6.1, the Company shall reimburse BDEC, upon submission by BDEC of an invoice and
necessary supporting  documentation,  for any Business Expense properly incurred
by BDEC in accordance with this Agreement.

     6.4 Use  Payment.  Company  agrees to pay (the "Use  Payment") to BDEC on a
monthly  basis as  compensation  for BDEC's grant to Company of the right to use
the Premises and common areas of the Buildings. The Use Payment for the Premises
in Building P shall be twelve percent (12%),  and for the Premises in Building T
shall be  thirty-six  percent (36%) of the rent and all other costs and expenses
incurred by BDEC pursuant to the Base Lease for each of the respective building.
The Use  Payment  shall be paid in advance  and shall be due and  payable on the
first day of each month during the Term.


                                                  ARTICLE VII
                                              TERM AND TERMINATION

     7.1 Term.  This  Agreement  shall be effective  for an initial  period (the
"Term") commencing on the Effective Date and ending September 1, 2004.

     7.2 Termination.  The Company may terminate this Agreement immediately upon
the occurrence of one of the following events:

     (1) the dissolution or bankruptcy of BDEC; or

     (2) after the  expiration  of a ninety  (90) day  period in which  BDEC has
failed to remedy its failure to perform its duties  under this  Agreement  after
having received written notice from the Company of BDEC's failure to perform its
duties under this Agreement, which notice must specify the failure to perform.

     7.3  Termination  by  Agreement.  In the event the  Company  and BDEC shall
mutually  agree  in  writing,  this  Agreement  may be  terminated  on the  date
specified in such written agreement.

         7.4 Effects of  Termination.  Upon  termination of this  Agreement,  as
hereinabove  provided,  no party  shall have any further  obligations  hereunder
except for (i) obligations  accruing prior to the date of termination,  and (ii)
obligations,  promises, or covenants set forth herein that are expressly made to
extend beyond the Term, including, without limitation,  payment of accrued money
due under  Article VI, if any, and the  authority  and limited power of attorney
granted to BDEC herein, which shall survive until such time as such obligations,
promises,  or  covenants  shall  be  fully  paid  and  satisfied  (all of  which
provisions  shall survive the  expiration  or  termination  of this  Agreement).
Notwithstanding  anything  to the  contrary  herein,  upon  termination  of this
Agreement for any reason,  all accrued Service Fees,  Business  Expenses and Use
Payments,  if any,  shall  become  immediately  due and payable to BDEC  without
demand or notice.

                                                  ARTICLE VIII
                                                  MISCELLANEOUS

     8.1 Notices. Any notice, request, demand,  instruction,  communication,  or
other document required, permitted, or desired to be given hereunder shall be in
writing  and,  except  as  otherwise  provided  for  herein,   shall  be  deemed
effectively  given:  (a) on receipt if  delivered  personally  or by  commercial
courier service or if sent by prepaid telex,  telegram, by facsimile or by other
instantaneous  electronic  transmission  device,  or (b) on the  fifth day after
deposit (unless a different date is shown on the return receipt) if sent postage
prepaid registered or certified United States mail, return receipt requested, as
follows:

                  Company:                  Prime/BDEC Acquisition, L.L.C.
                                            1301 Capital of Texas Highway
                                            Suite C-300
                                            Austin, Texas 78746

                                            Attn.:            President
                                            Facsimile:  (512) 314-4398

                  BDEC:                     Barnet Dulaney Eye Center, P.L.L.C..
                                            4800 North 22nd Street
                                            Phoenix, Arizona  85016
                                            Attn.: Mark Rosenberg
                                            Facsimile:  (602) 508-4889

or to such other  address,  or to the attention of such other person or officer,
as either party may by written notice designate.

     8.2 Governing  Law. This  Agreement has been executed and delivered in, and
shall be governed by, and construed and enforced in accordance with, the laws of
the State of Texas.  Proper venue for any action with respect to this  Agreement
shall be Dallas County, Texas.

     8.3  Assignment.  Except  as may be  herein  specifically  provided  to the
contrary,  this Agreement  shall inure to the benefit of and be binding upon the
parties  hereto and their  respective  legal  representatives,  successors,  and
assigns;  provided,  however,  that  neither  party may  assign  its  rights and
obligations under this Agreement without the prior written consent of the other.

     8.4 No Waiver.  The failure of either  party to insist at any time upon the
strict  observance  or  performance  of any  provision  of this  Agreement or to
exercise any right or remedy as provided in this Agreement  shall not impair any
right or  remedy of such  party or be  construed  as a waiver or  relinquishment
thereof with respect to subsequent defaults or breaches.  Every right and remedy
given by this Agreement to the parties hereto may be exercised from time to time
and as often as may be deemed xpedient by the appropriate party.

     8.5  Consents,  Approvals,  and  Exercise of  Discretion.  Except as may be
herein specifically  provided to the contrary,  whenever this Agreement requires
any consent or approval to be given by either party, or either party must or may
exercise  discretion,  the parties agree that such consent or approval shall not
be unreasonably  withheld or delayed,  and such  discretion  shall be reasonably
exercised.


     8.6  Severability.  In the event any provision of this Agreement is held to
be invalid,  illegal,  or unenforceable for any reason and in any respect,  such
invalidity,  illegality,  or unenforceability  shall not affect the remainder of
this  Agreement,  if the remainder of this  Agreement can be enforced to achieve
its purposes equitably to both parties.

     8.7 Divisions and Headings.  The division of this  Agreement into articles,
sections,  and  subsections  and the use of captions and headings in  connection
therewith are solely for convenience and shall not affect in any way the meaning
or interpretation of this Agreement.

     8.8 Sales and Use Tax.  BDEC and the  Company  acknowledge  and agree  that
certain of the services to be provided by BDEC hereunder may be subject to state
sales and use taxes and that BDEC may have a legal  obligation  to collect  such
taxes from the Company and to remit same to the State. The Company agrees to pay
the  applicable  state  sales and use taxes in  respect  of the  portion  of the
Services  Fee  attributable  to such  services,  and  grants  BDEC the  right to
withdraw and disburse from the bank accounts of the Company amounts necessary to
timely and fully pay such taxes.

         8.9  Entire  Agreement.  With  respect  to the  subject  matter of this
Agreement,  this Agreement supersedes all previous contracts and constitutes the
entire  agreement  between  the  parties.  Neither  party  shall be  entitled to
benefits other than those specified  herein. No oral statements or prior written
material not specifically  incorporated herein shall be of any force and effect,
and no changes in or  additions to this  Agreement  shall be  recognized  unless
incorporated  herein by amendment  in writing and signed by all parties  hereto.
Such  amendment(s)  shall  become  effective  on the  date  stipulated  in  such
amendment(s).  The parties  specifically  acknowledge that, in entering into and
executing this Agreement,  the parties rely solely upon the  representations and
agreements contained in this Agreement and no others.

         8.10 Audit Rights.  During the Term of this  Agreement and for a period
of two (2) years after any  termination  or  expiration of this  Agreement,  the
Company and each of its members shall be entitled to audit and inspect the books
and records of BDEC for purposes of  determining  the  propriety of all Business
Expenses,  Services  Fees and Use  Payments  charged to the  Company  under this
Agreement.  BDEC agrees to maintain,  throughout such period,  detailed  records
supporting  all amounts  charged to, or reimbursed  by, the Company  pursuant to
this  Agreement  and to  cooperate  fully with,  and to make its  employees  and
records  available  during  normal  business  hours to,  the  auditors  or other
representatives  of the Company or its  members  performing  such  audit.  Audit
rights may not be exercised  more  frequently  than once in every  eighteen (18)
month period and all costs and expenses  associated  therewith shall be borne by
the party  exercising  audit rights unless any such inspection  reveals that the
Company has overpaid,  by at least  $25,000,  any amounts which should have been
properly  paid or  reimbursed  to BDEC in  accordance  with  the  terms  of this
Agreement.  BDEC shall be entitled  to receive at least  thirty (30) days' prior
written  notice of the exercise of audit  rights prior to the  beginning of such
inspection.

                                             [Signature page follows]




<PAGE>





                                                 SIGNATURE PAGE TO
                                               COLLOCATION AGREEMENT


     IN WITNESS WHEREOF, the parties have executed this Agreement as of the date
first written above.


     COMPANY:                   PRIME/BDEC ACQUISITION, L.L.C.


                                By: /s/ Cheryl Williams

                                Name: Cheryl Williams

                                Title: Treasurer



     BDEC:                      BARNET DULANEY EYE CENTER, P.L.L.C.


                                By: /s/ Ronald W. Barnet, M.D.
                                Ronald W. Barnet, M.D., manager


                                By: /s/ David D. Dulaney, M.D.
                                David D. Dulaney, M.D., manager





<PAGE>





















                                                     EXHIBIT A

                                               Pro Forma Annualized
                                                  Facility Model


<PAGE>




                                                     EXHIBIT B

                                                     EMPLOYEES





<PAGE>






                               MEMBERSHIP INTEREST

                         TRANSFER RESTRICTION AGREEMENT

     This Membership Interest Transfer Restriction  Agreement (this "Agreement")
is entered into  effective as of the 1st day of  September,  1999,  by and among
LASIK Investors,  L.L.C., a Delaware limited  liability company (the "Company"),
Prime  Medical  Operating,  Inc., a Delaware  corporation  ("Prime"),  Ronald W.
Barnet, M.D.  ("Barnet"),  David D. Dulaney,  M.D.  ("Dulaney"),  Mark Rosenberg
("Rosenberg"),  Scott A. Perkins, M.D. ("Perkins"),  and Robert B. Pinkert, O.D.
("Pinkert").  Barnet, Dulaney, Rosenberg, Perkins and Pinkert, together with any
subsequent  Members in the Company who  hereafter  execute this  Agreement,  are
collectively referred to herein as the "Members".

                                R E C I T A L S:

             WHEREAS,  Barnet, Dulaney,  Rosenberg,  Perkins and Pinkert own all
the  issued  and  outstanding  membership  interests  of the  Company  (all such
membership  interests,  together with any hereafter  acquired,  are  hereinafter
referred to as the "Membership Interests"); and

             WHEREAS, this Agreement is a "Transaction  Document," as defined in
that  certain  Contribution  Agreement  (the  "Contribution   Agreement")  dated
effective September 1, 1999, by and among Prime, Prime Medical Services, Inc., a
Delaware corporation ("PMSI"), the Company, Barnet Dulaney Eye Center, P.L.L.C.,
an  Arizona  professional  limited  liability  company,  Prime/BDR  Acquisition,
L.L.C., a Delaware limited liability company, Prime/BDEC Acquisition,  L.L.C., a
Delaware limited liability company, Barnet, Dulaney and Rosenberg.

             WHEREAS,  the  Members,  the Company and Prime desire to enter into
this Agreement to control the distribution of ownership interests in the Company
and to promote the harmonious management of the Company's affairs.

             NOW,  THEREFORE,  in  consideration  of the  foregoing,  the mutual
covenants and agreements contained herein, and for other valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

                                    ARTICLE I

               PERMITTED TRANSFERS; RESTRICTIONS AGAINST TRANSFER

As used in this Agreement,  "Permitted Transfers" shall mean any transfer of all
or any  part of any  Member's  Membership  Interest  to (i) the  members  of the
immediate  family of the Member or a trust or trusts for the  benefit of members
of the immediate family of the Member, provided that after any such transfer the
Member  retains  the sole  express  right to vote,  or direct  the votes of, the
Membership  Interest,  (ii) any other  Member,  provided that after any transfer
pursuant to this subsection  (ii) is consummated,  Barnet and Dulaney (or trusts
that hold Membership Interests as a result of Permitted Transfers subsection (i)
above) must  collectively own in the aggregate at least fifty-one  percent (51%)
of the total outstanding  Membership  Interests of the Company,  or (iii) Prime.
Any Member  transferring all or a portion of its Membership Interest pursuant to
a  Permitted  Transfer  shall  give  written  notice of the  Permitted  Transfer
(containing the same  information as required for notice under Section 2.1.1) to
Prime and the other Members fifteen (15) days prior to the effective date of the
Permitted Transfer. Except for a Permitted Transfer, or as otherwise provided in
this Agreement, a Member shall not transfer, assign, pledge,  hypothecate, or in
any way alienate any  Membership  Interest,  or any  interest  therein,  whether
voluntarily  or by operation of law, or by gift or otherwise,  without the prior
written consent of the Company,  the other Members and Prime,  which consent may
be withheld in their sole and absolute  discretion.  Any  purported  transfer in
violation of any  provision  of this  Agreement  shall be void and  ineffectual,
shall not operate to transfer any interest or title to the purported transferee,
and shall give the Company, the other Members and Prime options to purchase such
Membership Interest in the manner and on the conditions hereinafter provided. As
used in this Agreement,  "Option  Members" shall mean all Members of the Company
except  (i) the Member  who,  prior to the  proposed  transfer  or the  incident
resulting in the proposed transfer of all or a portion of a Membership Interest,
owned such interest and (ii) Rosenberg.

                                   ARTICLE II

                                     OPTIONS

2.1          OPTION UPON VOLUNTARY TRANSFER.

             2.1.1  Notice of  Intention  to  Transfer.  If a Member  intends to
voluntarily  transfer any of its Membership  Interest,  other than pursuant to a
Permitted  Transfer,  to any person other than the Company,  and does not obtain
the written consents required in ARTICLE I hereof, the Member shall give written
notice to the other  Members,  Rosenberg  and Prime stating (i) the intention to
transfer a Membership  Interest,  (ii) the amount of  Membership  Interest to be
transferred,  (iii) the name,  business  and  residence  address of the proposed
transferee,  (iv) the nature and amount of the consideration,  and (v) the other
terms of the proposed sale.

             2.1.2 Option to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days after  receipt of the notice of intent to transfer,  an
option  to  purchase  all  or  any  portion  of  the  Membership   Interest  the
transferring Member intends to transfer,  for the price and upon the other terms
stated in the notice of intent to transfer.  If the Option Members fail,  within
such 30-day period,  to exercise  their purchase  option (by delivery of written
notice) with respect to the entire Membership  Interest being  transferred,  the
Option  Members shall be deemed to have elected not to exercise  their  purchase
option with respect to such unpurchased Membership Interest.  Upon any notice of
non-exercise (or deemed  non-exercise) by the Option Members,  Rosenberg (if not
the transferring  Member) shall have, and may exercise within 30 days of receipt
of notice of such non-exercise (or deemed  non-exercise),  an option to purchase
all or any portion of such unpurchased  Membership  Interest upon the same terms
and conditions.  If Rosenberg fails,  within such 30-day period, to exercise his
purchase  option (by  delivery  of written  notice)  with  respect to the entire
unpurchased  Membership Interest,  Rosenberg shall be deemed to have elected not
to  exercise  his  purchase  option  with  respect to any  remaining  Membership
Interest. Upon any notice of non-exercise (or deemed non-exercise) by Rosenberg,
Prime shall have,  and may exercise  within 30 days of receipt of notice of such
non-exercise  (or  deemed  non-exercise),  an  option  to  purchase  all of such
remaining Membership Interest upon the same terms and conditions.

             2.1.3 Death Before Closing.  If a Member who proposed to transfer a
Membership  Interest  dies  prior  to the  closing  of  the  sale  and  purchase
contemplated  by this  Section  2.1, the  Membership  Interest of such  deceased
Member shall be the subject of sale and purchase under Section 2.3.

             2.1.4 Allowable  Consideration.  All parties hereto acknowledge and
agree that it would be  impractical  to exercise  an option to purchase  arising
pursuant to this Section 2.1 whenever the proposed  consideration to be received
by the transferring  Member is other than cash or cash  equivalents.  Therefore,
the parties agree that no transfer  shall be permitted and no option shall arise
pursuant to this Section 2.1 whenever the  consideration to be received from the
proposed transferee is other than cash or cash equivalents.

2.2          OPTION UPON CERTAIN INVOLUNTARY TRANSFERS.

             2 2.1  Exercise  Event and  Notice.  The filing of a  voluntary  or
involuntary petition of bankruptcy by or on behalf of a Member, an assignment by
a Member of any of its Membership Interest, or of any right or interest therein,
for the benefit of creditors, or the voluntary transfer,  transfer by law or any
other transfer,  of any Membership Interest, or of any right or interest therein
(other  than  transfers  governed by ARTICLE I or  Sections  2.1,  2.3 or 2.4 or
ARTICLE  VII  hereof),  shall give the other  Members,  Rosenberg  and Prime the
option to  purchase  the  Membership  Interest of such  bankrupt  Member or such
transferred  Membership  Interest  as  provided  herein.  Upon the  filing  of a
voluntary or  involuntary  petition of bankruptcy by or on behalf of a Member or
an assignment by Member of any of its  Membership  Interest,  or of any right or
interest  therein,  for the  benefit of  creditors,  the Member or its  personal
representative  shall  promptly  give written  notice of such  occurrence to the
other  Members,  Rosenberg  and Prime.  In the event of a transfer of Membership
Interest,  as described above, the Member  transferring such Membership Interest
shall  promptly  give  written  notice of such  transfer  to the other  Members,
Rosenberg and Prime.

             2.2.2 Option to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days after receipt of the notice of the applicable  exercise
event,  an option to purchase all or any portion of the Membership  Interest the
bankrupt or transferring Member intends to transfer,  for the price and upon the
other terms hereinafter provided. If the Option Members fail, within such 30-day
period,  to exercise their purchase  option (by delivery of written notice) with
respect to the entire Membership Interest being transferred,  the Option Members
shall be deemed to have  elected  not to  exercise  their  purchase  option with
respect to such unpurchased Membership Interest. Upon any notice of non-exercise
(or deemed  non-exercise) by the Option Members,  Rosenberg (if not the bankrupt
or  transferring  Member) shall have, and may exercise within 30 days of receipt
of notice of such non-exercise (or deemed  non-exercise),  an option to purchase
all or any portion of such  unpurchased  Membership  Interest  for the price and
upon the other terms  hereinafter  provided.  If  Rosenberg  fails,  within such
30-day period,  to exercise his purchase  option (by delivery of written notice)
with respect to the entire unpurchased  Membership Interest,  Rosenberg shall be
deemed to have elected not to exercise  his purchase  option with respect to any
remaining  Membership  Interest.  Upon any  notice of  non-exercise  (or  deemed
non-exercise) by Rosenberg, Prime shall have, and may exercise within 30 days of
receipt of notice of such  non-exercise (or deemed  non-exercise),  an option to
purchase all of such  remaining  Membership  Interest for the price and upon the
other terms hereinafter provided.

2.3          PURCHASE AND SALE OF MEMBERSHIP INTEREST UPON DEATH.

             2.3.1  Notice  of  Death.  Upon  the  death  of  the  Member,   the
representative  of the estate of the deceased Member shall promptly give written
notice of the death to the other Members, Rosenberg and Prime.

             2.3.2 Option to Purchase.  The Option  Members shall have,  and may
exercise  within 30 days  after  receipt  of the  notice of death,  an option to
purchase all or any portion of the Membership  Interest of the deceased  Member,
for the price and upon the  other  terms  hereinafter  provided.  If the  Option
Members fail,  within such 30-day period,  to exercise their purchase option (by
delivery of written  notice)  with  respect to the  entirety of such  Membership
Interest,  the Option  Members  shall be deemed to have  elected not to exercise
their purchase option with respect to such unpurchased Membership Interest. Upon
any notice of  non-exercise  (or  deemed  non-exercise)  by the Option  Members,
Rosenberg (but not his estate if he is the deceased  Member) shall have, and may
exercise  within 30 days of  receipt of notice of such  non-exercise  (or deemed
non-exercise),  an option to  purchase  all or any  portion of such  unpurchased
Membership Interest for the price and upon the other terms hereinafter provided.
If Rosenberg fails,  within such 30-day period,  to exercise his purchase option
(by  delivery  of  written  notice)  with  respect  to  the  entire  unpurchased
Membership  Interest,  Rosenberg shall be deemed to have elected not to exercise
his purchase option with respect to any remaining Membership Interest.  Upon any
notice of non-exercise (or deemed non-exercise) by Rosenberg,  Prime shall have,
and may exercise  within 30 days of receipt of notice of such  non-exercise  (or
deemed  non-exercise),  an option to purchase all of such  remaining  Membership
Interest for the price and upon the other terms hereinafter provided.

2.4  OPTION UPON DEATH OF A MEMBER'S SPOUSE, TERMINATION OF MARITAL RELATIONSHIP
     OR PARTITION OF COMMUNITY PROPERTY.

             2.4.1  Death of  Member's  Spouse.  Each  Member and each  Member's
spouse  agree that in the event the spouse of a Member  predeceases  such Member
and such Member does not succeed by the spouse's  last will and  testament or by
operation of law to any interest  (including,  without  limitation,  a community
property interest) of the spouse in the Membership  Interest,  such Member shall
have, and may exercise  within 60 days after the death of the spouse,  an option
to purchase all or any portion of the  spouse's  interest for the price and upon
the other terms hereinafter  provided.  If the Member fails,  within such 60-day
period,  to exercise  his purchase  option (by delivery of written  notice) with
respect to the entirety of such spouse's  interest,  that Member shall be deemed
to have  elected  not to  exercise  his  purchase  option  with  respect to such
spouse's interest.  Upon any notice of non-exercise (or deemed  non-exercise) by
the Member,  the Option Members shall then have, and may exercise within 30 days
after  receipt  of such  non-exercise  (or  deemed  non-exercise),  an option to
purchase all or any portion of the deceased spouse's interest, for the price and
upon the other terms  hereinafter  provided.  If the Option Members fail, within
such 30-day period,  to exercise  their purchase  option (by delivery of written
notice) with respect to the entirety of such  deceased  spouse's  interest,  the
Option  Members shall be deemed to have elected not to exercise  their  purchase
option with respect to such unpurchased  deceased  spouse's  interest.  Upon any
notice of non-exercise (or deemed non-exercise) by the Option Members, Rosenberg
(if not the Member whose spouse is deceased) shall have, and may exercise within
30 days of receipt of notice of such non-exercise (or deemed  non-exercise),  an
option to purchase  all or any  portion of such  unpurchased  deceased  spouse's
interest  for the  price  and upon the  other  terms  hereinafter  provided.  If
Rosenberg fails,  within such 30-day period, to exercise his purchase option (by
delivery of written  notice)  with  respect to the entire  unpurchased  deceased
spouse's interest, Rosenberg shall be deemed to have elected not to exercise his
purchase option with respect to any remaining  portion of the deceased  spouse's
interest. Upon any notice of non-exercise (or deemed non-exercise) by Rosenberg,
Prime shall have,  and may exercise  within 30 days of receipt of notice of such
non-exercise  (or  deemed  non-exercise),  an  option  to  purchase  all of such
remaining  portion of the deceased  spouse's interest for the price and upon the
other terms hereinafter provided.

             2.4.2 Termination of Marital Relationship or Partition of Community
Property. In the event a divorce,  annulment or other proceeding for termination
of the  marital  relationship  is  filed by or  against  a  Member,  or upon the
initiation  of any voluntary or  involuntary  attempt to partition the community
property  estate between a Member and such Member's  spouse for any reason,  the
Member shall promptly give written notice to the other Members,  Rosenberg,  and
Prime, of such event.  The Member shall have, and may exercise within 60 days of
giving of such notice, an option to purchase all or any portion of the departing
spouse's interest in such Membership  Interest (including without limitation any
community  property interest,  for purposes of this Section),  for the price and
upon the other terms  hereinafter  provided.  If the Member  fails,  within such
60-day period,  to exercise his purchase  option (by delivery of written notice)
with respect to the  entirety of such  spouse's  interest,  that Member shall be
deemed to have elected not to exercise his purchase  option with respect to such
spouse's interest.  Upon any notice of non-exercise (or deemed  non-exercise) by
the Member,  the Option Members shall then have, and may exercise within 30 days
after  receipt  of such  non-exercise  (or  deemed  non-exercise),  an option to
purchase all or any portion of the departing  spouse's  interest,  for the price
and upon the other  terms  hereinafter  provided.  If the Option  Members  fail,
within such 30-day period,  to exercise  their  purchase  option (by delivery of
written  notice)  with  respect  to the  entirety  of  such  departing  spouse's
interest,  the Option  Members  shall be deemed to have  elected not to exercise
their  purchase  option  with  respect to such  unpurchased  departing  spouse's
interest. Upon any notice of non-exercise (or deemed non-exercise) by the Option
Members, Rosenberg (if not the Member whose spouse is departing) shall have, and
may exercise within 30 days of receipt of notice of such non-exercise (or deemed
non-exercise),  an option to  purchase  all or any  portion of such  unpurchased
departing  spouse's  interest for the price and upon the other terms hereinafter
provided.  If  Rosenberg  fails,  within such  30-day  period,  to exercise  his
purchase  option (by  delivery  of written  notice)  with  respect to the entire
unpurchased  departing  spouse's  interest,  Rosenberg  shall be  deemed to have
elected not to  exercise  his  purchase  option  with  respect to any  remaining
portion of the departing spouse's interest.  Upon any notice of non-exercise (or
deemed non-exercise) by Rosenberg,  Prime shall have, and may exercise within 30
days of receipt of notice of such  non-exercise  (or  deemed  non-exercise),  an
option to  purchase  all of such  remaining  portion of the  departing  spouse's
interest for the price and upon the other terms hereinafter provided.

2.5          ALTERNATE NOTICES.

             The failure of any  person,  whether a party to this  Agreement  or
otherwise,  to give notice of the occurrence of an Exercise Event (as defined in
Section 4.3) as contemplated herein shall not operate to prevent the creation of
any option which would otherwise arise pursuant to this ARTICLE II. Any party to
this  Agreement who has actual  knowledge of the occurrence of an Exercise Event
may give the required written notice of the occurrence of an Exercise Event, and
upon the giving of such written  notice the options  shall be created and become
exercisable  to the  same  extent  as if such  notice  was  given  by the  party
initially contemplated above. For instance, and purely by way of example, in the
event of the death of a Member,  another  Member having actual  knowledge of the
Member's  death  may give the  notice  initially  contemplated  to be given by a
representative  of the estate of the deceased  Member  pursuant to Section 2.3.1
above,  whereupon the Option  Members'  option  described in Section 2.3.2 would
arise and become  exercisable to the same extent as if the notice had been given
by the representative of the estate of the deceased Member.

                                   ARTICLE III

                   EXERCISE OF OPTIONS; EFFECT OF NON-EXERCISE

3.1          MANNER OF EXERCISE OF OPTIONS.

             All options granted in, or arising pursuant to, ARTICLE II shall be
exercised by a written notice to that effect  delivered within the time provided
for the exercise of the option.

3.2          COMPLETE EXERCISE OF OPTIONS.

             Notwithstanding  anything  herein to the  contrary,  the holders of
options granted in, or arising pursuant to, ARTICLE II must,  either alone or in
the  aggregate,  exercise the options in such a manner as to purchase all of the
Membership  Interest (or interest therein) subject to such options,  and failure
to do so shall cause a forfeiture of the options.

3.3          MULTIPLE OPTION HOLDERS.

             In cases  where an option is held by more than one  Option  Member,
each  purchasing  Option  Member  shall  be  entitled  to  purchase  his  or her
proportionate  share of the Membership Interest subject to the option. An Option
Member's  proportionate  share  shall  equal  the  total  amount  of  Membership
Interests  subject to the option multiplied by a fraction the numerator of which
is the  amount  of  Membership  Interests  held by such  Option  Member  and the
denominator  of which shall be the amount of  Membership  Interests  held by all
Option Members electing to exercise the option.

3.4          EFFECT OF NON-EXERCISE OF OPTIONS.

             If the  holders of options  granted  or  arising  pursuant  to this
Agreement do not exercise  their  options,  or such  options are  forfeited,  as
provided herein,  the person or persons  acquiring the Membership  Interests (or
interest  therein)  that  were  the  subject  of the  options  shall  execute  a
counterpart  of this  Agreement  and  become a party  hereto and shall hold such
Membership  Interests  subject to all the terms and conditions  provided herein,
and any transfer of such Membership  Interests (or interest  therein) shall only
be made in accordance  with the terms and  conditions  provided  herein.  In the
event the person or persons  acquiring  the  Membership  Interests  (or interest
therein)  fail to execute a  counterpart  of this  Agreement  and become a party
hereto,  such transfer shall be void and  ineffectual,  and shall not operate to
transfer any interest or title to the purported  transferee and such  Membership
Interests shall thereafter be subject to cancellation and  extinguishment by the
Company,  without  consideration  therefor.  In  addition,  in  the  event  of a
voluntary  transfer  subject to the provisions of Section 2.1, upon the lapse or
forfeiture of the options arising pursuant to that Section, the Member proposing
the  transfer  shall have the right to  effectuate  the  transfer of  Membership
Interests  in  accordance  with the  terms  stated  in the  notice  of intent to
transfer,  and the  transferee of such  Membership  Interests  shall execute and
become a party to this  Agreement  and  shall  hold  such  Membership  Interests
subject to all of its terms and conditions.  Provided further, however, any such
transfer of Membership  Interests shall be void and  ineffectual,  and shall not
operate to transfer any interest or title to the  purported  transferee,  if (i)
the  transfer  is not upon the terms or is not to the  transferee  stated in the
notice of intent to transfer,  or (ii) the transfer is not closed within 10 days
of receipt of written notice of the election not to exercise,  or the forfeiture
of, all applicable options.

                                   ARTICLE IV

                                 PURCHASE PRICE

4.1          PURCHASE PRICE.

             The  purchase  price of the  Membership  Interests  to be purchased
pursuant to options granted, held or exercised pursuant to Sections 2.2, 2.3 and
2.4  hereof,  shall be the amount  calculated  in  accordance  with  Section 4.2
hereof.

4.2          CALCULATION OF PURCHASE PRICE.

             When  determined in accordance  with this Section 4.2, the purchase
price for the Membership  Interest or any portion  thereof or spouse's  interest
therein shall be equal to the Appraised  Value of the Membership  Interest as of
the Valuation Date (as defined in Section 4.3 hereof), reduced when necessary to
reflect the purchase of less than a one hundred  percent (100%) interest in each
of the Membership Interests to be transferred (for example:  reduced by one-half
when a  spouse's  interest  is only an  undivided  one-half  community  property
interest in each of the Membership  Interests of a Member spouse).  For purposes
of this Agreement,  the "Appraised Value" of a Membership  Interest shall be (i)
based on the overall value of the Company as a going concern, expressed in a per
Membership Interest unit amount without  consideration to whether the Membership
Interest,  or interest therein,  being transferred  constitutes a controlling or
minority  interest in the Company,  and (ii) determined by a certified  business
appraiser,  selected  by the  Company,  that is a member of either the  American
Society of Appraisers or the Institute of Business  Appraisers;  but if a Member
or Prime  disagrees  with such  determination  that  Member or Prime may, at its
expense,  have another certified  business  appraiser that is a member of one or
both of the above named professional  organizations  determine the value, and if
the two appraisers cannot agree upon a value, they shall mutually select a third
certified  business  appraiser  (that  meets  the  above  described   membership
requirements) who shall,  together with the first two appraisers,  determine the
value of the  Membership  Interest by majority  vote.  The expense of such third
appraiser  shall  also be paid by the  Member or Prime,  as the case may be, who
disagrees  with the value  determination  of the Company's  original  appraiser,
unless the appraised value ultimately  determined is more than ten percent (10%)
greater than the value determined by the Company's original appraiser.

4.3          CERTAIN DEFINITIONS.

             As used herein,  the term "Valuation  Date" shall mean and refer to
the end of the fiscal year of the Company  immediately  preceding  the  Exercise
Event,  unless the purchasing party elects to use the alternate  valuation date,
in which  event the  Valuation  Date  shall be the end of the month  immediately
preceding the Exercise  Event. As used herein,  the term "Exercise  Event" shall
mean and refer to the event or  circumstance  described  in  ARTICLE  II of this
Agreement, as a result of which the Company, a Member, or Prime, as the case may
be in the first  instance,  becomes  entitled  to  exercise  a  purchase  option
hereunder.

                                    ARTICLE V

                          PAYMENT OF THE PURCHASE PRICE

5.1          PAYMENT.

             Except as otherwise  provided in this Agreement,  including Section
2.1, the purchase price for a Membership Interest to be purchased from a selling
party shall either: (i) be paid in cash; or (ii) at the option of the purchasing
party,  up to seventy  percent (70%) of the purchase  price may be deferred with
the remainder paid in cash at the closing.

5.2          PROMISSORY NOTE.

             If the purchasing  party elects to defer part of the purchase price
by the execution and delivery of a promissory  note, the deferred portion of the
price shall be evidenced by the promissory  note of the purchasing  party to the
order of the selling party payable in sixty (60) equal monthly  installments  of
principal  and interest on or before the first day of each month  beginning  the
month next following the date of closing. The interest rate for such installment
promissory  note shall be equal to the prime or base rate on corporate  loans at
large U.S.  money center  commercial  banks as  published  in the "Money  Rates"
column of the Wall  Street  Journal  on the date of  exercise  of the  option to
purchase  (or, if such option is not  exercised  on a date on which such rate is
published, the next following date on which such rate is published). In no event
shall the interest rate exceed the maximum legal  interest rate then  prevailing
for such obligations in the state of Texas. The note shall be secured by a first
lien security interest in the Membership Interest transferred and the purchasing
party shall  deliver  certificates  evidencing  the  Membership  Interest to the
selling party and take such further action as is reasonably necessary to perfect
the security interest.

                                   ARTICLE VI

                                   THE CLOSING

             Unless otherwise agreed by the parties, the closing of the sale and
purchase of a Membership  Interest shall take place at the principal  offices of
the Company within sixty (60) days after the exercise of any option  provided by
this Agreement.  Each party hereto  (including the spouses of the Members) shall
bear its own transaction  costs,  including  legal and accounting  fees, if any,
attributable to any transfer of a Membership Interest,  or any interest therein,
pursuant to this  Agreement.  Upon the closing,  the selling party shall deliver
its  Membership  Interest  to the  purchaser  free and  clear of all  liens  and
encumbrances,  and shall deliver to the Company its  resignation and that of all
of its nominees, if any, as officers and directors of the Company and any of the
Company's subsidiaries.  The selling party shall deliver to the purchasing party
at closing, all appropriate documents of transfer,  including without limitation
bills of sale, assignments or other instruments of conveyance. As a condition to
any closing of the sale and purchase of a  Membership  Interest (or any interest
therein) pursuant to this Agreement:  (i) the selling party shall be indemnified
by the purchasing party (in a form reasonably satisfactory to the selling party)
for all the Company's liabilities,  whether fixed or contingent,  to lenders and
others,  incurred prior to the closing of the  transaction,  (ii) the purchasing
party and/or the Company  shall cause the release of any personal  guaranties by
the  selling  party that the  selling  party may have  granted to the  Company's
lenders or other  creditors  or which may have  otherwise  been  provided by the
selling party for the benefit of the Company,  and (iii) if the selling party is
a creditor of the Company, the purchasing party shall unconditionally  guarantee
the debt of the Company to the  selling  party and execute  such  documents  and
instruments   of  guarantee  as  may  be  necessary  in  connection   therewith.
Furthermore,  and as a condition to closing, in the event the selling party owes
any amounts to the Company at the time of closing,  such  indebtedness  shall be
paid in full by the selling party at or prior to the closing, or may be deducted
from and offset  against the  purchase  price by the  purchasing  party,  in the
purchasing  party's  sole  discretion.  In the event of a failure  to close as a
result of the  non-satisfaction  of the  conditions to closing set forth herein,
this  Agreement  shall  remain  in full  force  and  effect  and all  Membership
Interests  shall remain  subject to the  restrictions  contained  herein and, in
addition,  the parties hereto shall be entitled to such other remedies as may be
available in the event the failure to close constitutes a breach hereof.

                                   ARTICLE VII

                             LEGEND ON CERTIFICATES

             All Membership  Interests now or hereafter owned by the Members, or
their  permitted  transferees,  shall  be  subject  to the  provisions  of  this
Agreement,  and any  certificates  representing  same shall  bear the  following
legend:

             "THE  MEMBERSHIP   INTEREST   REPRESENTED   HEREBY  AND  THE  SALE,
             ASSIGNMENT,  TRANSFER,  PLEDGE  OR OTHER  DISPOSITION  THEREOF  ARE
             SUBJECT TO CERTAIN RESTRICTIONS  CONTAINED IN A MEMBERSHIP INTEREST
             TRANSFER  RESTRICTION  AGREEMENT  AMONG THE  COMPANY AND THE WITHIN
             NAMED MEMBER, AND ANY AMENDMENT  THERETO.  THE AGREEMENT LIMITS THE
             USE OF THIS MEMBERSHIP  INTEREST AS COLLATERAL FOR ANY LOAN WHETHER
             BY PLEDGE,  HYPOTHECATION  OR OTHERWISE.  A COPY OF THE  MEMBERSHIP
             INTERES   TRANSFER   RESTRICTION   AGREEMENT  AND  ALL   APPLICABLE
             AMENDMENTS  THERETO  WILL BE FURNISHED BY THE COMPANY TO THE HOLDER
             HEREOF  WITHOUT  CHARGE UPON WRITTEN  REQUEST TO THE COMPANY AT ITS
             PRINCIPAL PLACE OF BUSINESS OR REGISTERED OFFICE."

                                  ARTICLE VIII

                            TERMINATION OF AGREEMENT

             This Agreement and all restrictions on Membership Interest transfer
created hereby shall terminate on the occurrence of any of the following events:

             (a)             The bankruptcy or dissolution of the Company.

     (b) The ownership by one person of all of the  Membership  Interests of the
Company which are then subject to this Agreement.

             (c) The execution of a written  instrument  by the Company,  all of
the Members who then own Membership  Interests  subject to this  Agreement,  and
Prime which terminates the same.

     (d) The date  twenty-one (21) years after the death of the last survivor of
all individuals who are parties to this Agreement.

                                   ARTICLE IX

                               GENERAL PROVISIONS

9.1          REMEDIES FOR BREACH.

             The  Membership  Interests are unique  chattels,  and each party to
this Agreement shall have the remedies which are available to him, her or it for
the violation of any of the terms of this Agreement,  including, but not limited
to, the equitable remedy of specific performance.

9.2          BINDING EFFECT.

             This  Agreement  is binding  upon and inures to the  benefit of the
Company,  its  successors  and  permitted  assigns,  to the  Members  and  their
respective heirs,  personal  representatives,  successors and permitted assigns,
and to Prime,  its successors and permitted  assigns.  This Agreement may not be
assigned,  in whole or in part, by any party hereto without the express  written
consent of all parties hereto.

9.3          PRIOR AGREEMENTS.

             This  Agreement  supersedes  all prior written and oral  agreements
between the parties regarding the subject matter hereof.

9.4          GOVERNING LAWS.

             This Agreement is executed under,  and in conformity with, the laws
of the State of Texas and shall be governed  thereby.  If any  provision of this
Agreement  shall be determined to be invalid or  unenforceable  or prohibited by
the laws of the State of Texas, this Agreement shall be considered  divisible as
to such provisions and such  provisions  shall be inoperative and shall not be a
part of the consideration  moving from any party to another party. The remaining
provisions  shall be valid and binding upon the parties and be of like effect as
though such invalid,  unenforceable  or prohibited  provisions were not included
herein.

9.5          AMENDMENT.

             This  Agreement  may be  amended  in whole  or in part  only by the
written consent of all the parties.  Such amendment shall be effective as of the
date then  determined by the parties and shall  supersede any provisions  herein
contained which are in conflict.

9.6          CAPTIONS AND GENDER.

             The captions and titles herein are for convenience only and are not
intended to include or  conclusively  define the subject matter of the text. All
pronouns and  references  thereto shall refer to the  masculine,  feminine,  and
neuter  genders,  singular  or plural,  as the  identification  of the  persons,
entities, and companies may require. The term "person" as used in this Agreement
shall include natural persons, companies,  partnerships, trusts, estates and any
other form of entity.

9.7          NOTICES.

             All notices  required to be given  hereunder  shall be deemed to be
duly given by  personally  delivering  such notice or by mailing it by certified
mail, to the Company,  to the Members,  and to Prime at the following  addresses
(which  may be  changed  by giving  written  notice of such  change to all other
parties hereto):

             To the Company: LASIK Investors, L.L.C.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Barnet:      Ronald W. Barnet, M.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Dulaney:     David D. Dulaney, M.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Rosenberg:   Mark Rosenberg
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Perkins:     Scott A. Perkins, M.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Pinkert:     Robert B. Pinkert, O.D.
                             4800 North 22nd Street
                             Phoenix, Arizona 85016

             To Prime:        Prime Medical Operations, Inc.
                              Attention: President
                              1301 Capital of Texas Highway
                              Austin, Texas 78746

9.8  BINDING EFFECT OF THIS AGREEMENT ON ADDITIONAL MEMBERSHIP INTEREST ACQUIRED
     BY A MEMBER.

             In the event a Member acquires,  contracts to acquire,  or receives
any Membership  Interests of the Company which are not subject to this Agreement
at the time of acquisition,  such additional  Membership Interests of the Member
shall  be   automatically   subject  to  this  Agreement  and  any  certificates
representing  such Membership  Interests shall bear the legend prescribed herein
and this Agreement shall be amended, if necessary, to reflect the acquisition of
such Membership Interests by the Member.

9.9          EXECUTION OF DOCUMENTS.

             Whenever Membership Interests are to be purchased by the Company, a
Member, or Prime pursuant to this Agreement,  the transferor shall do all things
and execute and deliver all documents and make all transfers as may be necessary
to consummate such purchase.  In the event that the transferor  refuses to abide
by the terms and  conditions  specified  herein,  the  purchaser(s)  may  tender
payment  for such  Membership  Interest by mailing  payment to the  transferor's
attention  at the  address  of the  Company's  registered  office on file at the
office of the Texas Secretary of State.  After payment is tendered  accordingly,
the Company shall be entitled to cancel such  Membership  Interest on its books,
and reissue such Membership Interest to the purchaser(s) or, if the purchaser is
the Company,  the Company may hold such Membership Interest as treasury stock or
cancel such Membership Interest.

9.10         ACTIONS BY THE COMPANY.

             Any decision by the Company to exercise any purchase  option,  give
any notice or otherwise enforce any provisions of this Agreement,  shall be made
by a majority  vote of Members who are not then in breach of this  Agreement and
whose Membership Interests are not then the subject of any option or requirement
of notice of an Exercise Event.

                            [Signature pages follow]


<PAGE>


S-2

                                SIGNATURE PAGE TO

                               MEMBERSHIP INTEREST

                         TRANSFER RESTRICTION AGREEMENT

             EXECUTED as of the date first mentioned above.

             COMPANY:                        LASIK Investors, L.L.C.

                                             By: /s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                             By: /s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager

             BARNET:                            /s/ Ronald W. Barnet, M.D.

                                                 Ronald W. Barnet, M.D.


             DULANEY:                           /s/ David D. Dulaney, M.D.

                                                 David D. Dulaney, M.D.

             ROSENBERG:                         /s/ Mark Rosenberg

                                                 Mark Rosenberg

             Perkins:                           /s/ Scott A. Perkins, M.D.

                                                 Scott A. Perkins, M.D.


             Pinkert:                           /s/ Robert B. Pinkert, O.D.

                                                 Robert B. Pinkert, O.D.


             PRIME:                              Prime Medical Operating, Inc.

                                             By: /s/ Cheryl Williams
                                                 Printed Name:  Cheryl Williams
                                                 Title:  Treasurer



<PAGE>


                                SPOUSAL CONSENTS

             The  undersigned   spouse  of  Ronald  W.  Barnet,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                       Signature: /s/ Teri Barnet
                                       Printed Name: Teri Barnet

             The  undersigned   spouse  of  David  D.  Dulaney,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                       Signature: /s/ Anna Maria Dulaney
                                       Printed Name: Anna Maria Dulaney

             The undersigned  spouse of Mark Rosenberg  hereunto  subscribes her
name in evidence of her  agreement  and consent to the  disposition  made of any
interest  she may have,  including  any  community  property  interests,  in the
membership  interest of LASIK  Investors,  L.L.C.,  referred to in the foregoing
Agreement, and to all other provisions of such Agreement.

                                       Signature: /s/ J. Rosenberg
                                       Printed Name: J. Rosenberg

             The  undersigned   spouse  of  Scott  A.  Perkins,   M.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                       Signature: /s/ Lourdes S. Perkins
                                       Printed Name: Lourdes S. Perkins

             The  undersigned  spouse  of  Robert  B.  Pinkert,   O.D.  hereunto
subscribes her name in evidence of her agreement and consent to the  disposition
made of any interest she may have,  including any community property  interests,
in the  membership  interest  of LASIK  Investors,  L.L.C.,  referred  to in the
foregoing Agreement, and to all other provisions of such Agreement.

                                       Signature: /s/ Jodi C. Pinkert
                                       Printed Name: Jodi C. Pinkert


                                         ASSIGNMENT AND SECURITY AGREEMENT

         THIS ASSIGNMENT AND SECURITY  AGREEMENT (this  "Agreement") is made and
entered into as of the 1 day of September, 1999, by and between Prime Medical
Operating,  Inc.,  a  Delaware  corporation  (the  "Secured  Party")  and  LASIK
Investors, L.L.C., a Delaware limited liability company ("LASIK").

                                                     RECITALS:

         A. LASIK and Secured  Party have  executed and  delivered  that certain
Contribution  Agreement  dated  effective  September 1, 1999,  between and among
LASIK,  Secured  Party,  Prime/BDR  Acquisition,   L.L.C.,  a  Delaware  limited
liability  company (the  "Debtor"),  Prime  Medical  Services,  Inc., a Delaware
corporation  ("PMSI"),  Prime/BDEC  Acquisition,   L.L.C.,  a  Delaware  limited
liability company, Barnet Dulaney Eye Center,  P.L.L.C., an Arizona professional
limited liability company,  David D. Dulaney,  M.D., Ronald W. Barnet, M.D., and
Mark Rosenberg (the "Contribution Agreement"), and Debtor and Secured Party have
executed and delivered that certain Loan  Agreement,  dated September ____, 1999
(the "Loan  Agreement"),  pursuant to which Secured Party agrees to make certain
loans to Debtor on the terms and subject to the conditions provided therein.

     B. Secured Party has requested that LASIK pledge the Collateral (as defined
below) to secure  certain  obligations  and  liabilities  that Debtor may now or
hereafter have to Secured Party, including,  without limitation, any obligations
arising under loans made pursuant to the Loan Agreement.

         C. LASIK desires to enter into this Agreement as a material  inducement
to Secured Party's extension of credit under the Loan Agreement.

                                                    AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and  sufficiency  of which LASIK  acknowledges,  LASIK and Secured Party
agree as follows:

                                                     ARTICLE I
                                        COLLATERAL AND SECURED OBLIGATIONS

     1.1 Grant of  Security  Interest.  LASIK  hereby  assigns,  transfers,  and
pledges to Secured  Party,  and LASIK hereby  grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"): --------------------------

     (a) Interest in  Subsidiary.  All  ownership  interests of LASIK in Debtor,
whether now existing or hereafter  acquired and including,  without  limitation,
that certain 40% membership interest in Debtor; ----------------------

          (b) Accounts. All accounts and rights now or hereafter attributable to
     any of the Collateral  described in (a) above,  and all rights of LASIK now
     or hereafter  arising  under any  agreement  pertaining  to the  Collateral
     described in (a) above,  including  without  limitation all  distributions,
     proceeds,  fees,  dividends,  preferences,  payments  or other  benefits of
     whatever  nature  which LASIK is now or may  hereafter  become  entitled to
     receive with respect to any Collateral described in (a) -------- above;

                  (c) Additional  Property.  "Collateral" shall also include the
following property (collectively, the "Additional Property") which LASIK becomes
entitled to receive or shall  receive as a result of its  ownership of any other
Collateral:  (i) any stock or other  ownership  certificate,  including  without
limitation,  any certificate representing a stock dividend or any certificate in
connection with any recapitalization,  reclassification,  merger, consolidation,
conversion,  sale of assets,  combination,  stock split, reverse stock split, or
spin-off;  (ii) any  option,  warrant,  subscription  or  right,  whether  as an
addition to or in substitution of any other  Collateral;  (iii) any dividends or
distributions  of any kind whatsoever,  whether  distributable in cash, stock or
other property;  (iv) any interest,  premium or principal payments;  and (v) any
conversion or redemption proceeds; and

          (d)  Proceeds.  All proceeds  (cash and  non-cash)  arising out of the
     sale,  exchange,  collection or other  disposition of all or any portion of
     the  Collateral  described  in (a),  (b) or (c)  above,  including  without
     limitation  proceeds  in  the  form  of  stock,  accounts,  chattel  paper,
     instruments, documents, goods, inventory and equipment. --------

The security interest in the Collateral hereby granted by LASIK to Secured Party
may sometimes be referred to in this Agreement as the "Security Interest".

          1.2 Obligations. This Agreement and the Security Interest shall secure
     full and punctual  payment and  performance of the following  indebtedness,
     duties and obligations (collectively, the "Obligations"): -----------

          (a) All  liabilities  and  obligations  of  Debtor  to  Secured  Party
     (including,  without limitation,  any principal,  interest,  fees and other
     amounts,  and  any  other  obligations)  under  and  pursuant  to the  Loan
     Agreement  and each  promissory  note  (collectively,  the  "Note")  issued
     pursuant to the Loan Agreement; and

          (b) All liabilities and obligations of LASIK to Secured Party, PMSI or
     any Prime  Indemnified  Parties (as defined in the Contribution  Agreement)
     under and pursuant to the Contribution Agreement or this Agreement.

                                   ARTICLE II
        LASIK'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

         LASIK hereby represents and warrants to Secured Party as follows:

          2.1 Ownership of Collateral.  LASIK has good and  marketable  title to
     the  Collateral   free  and  clear  of  any  liens,   security   interests,
     shareholders  agreement,  calls,  charge,  or encumbrance,  except for this
     Security  Interest.  No financing  statement or other instrument similar in
     effect  covering  all or any  part  of the  Collateral  is on  file  in any
     recording  office,  except as may have been filed in favor of Secured Party
     relating to this Agreement. -----------------------

          2.2  Power  &  Authority.  LASIK  has the  lawful  right,  power,  and
     authority to grant the Security Interest in the Collateral. This Agreement,
     together  with all filings and other  actions  necessary  or  desirable  to
     perfect and protect  such  security  interest,  which have been duly taken,
     create a valid  and  perfected  first  priority  security  interest  in the
     Collateral  securing  the  payment  and  performance  of  the  Obligations.
     -----------------

          2.3 No  Agreements.  The  Interests  are not  subject  to any right of
     redemption,  or any call or put options, voting trust, proxy,  shareholders
     agreement, right of first refusal, or any other document or agreement which
     would in any way impair or adversely  affect this Security  Interest or the
     rights of Secured Party under this Agreement. -------------

          2.4 Securities.  Any  certificates  evidencing  securities  pledged as
     Collateral are valid and genuine and have not been altered.  All securities
     pledged as Collateral  have been duly  authorized and validly  issued,  are
     fully  paid and  non-assessable,  and were not issued in  violation  of the
     preemptive  rights of any party or of any  agreement  by which LASIK or the
     issuer  thereof is bound.  Except as  expressly  provided  otherwise in the
     Contribution  Agreement or any Transaction  Document (as therein ----------
     defined),  no restrictions or conditions exist with respect to the transfer
     or voting of any securities pledged as Collateral.

                                                    ARTICLE III
                                   LASIK'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1  Solvency of LASIK.  As of the date  hereof,  (i) LASIK is solvent;
(ii) the fair saleable  value of LASIK's assets  exceeds its  liabilities  (both
fixed and  contingent);  (iii)  LASIK has  sufficient  capital to satisfy all of
LASIK's obligations as they become due; (iv) no receiver,  trustee, or custodian
has been appointed for, or taken possession of, all or substantially  all of the
assets of LASIK,  either in a  proceeding  brought  by LASIK or in a  proceeding
brought  against  LASIK;  (v) LASIK is not the subject of a petition  for relief
under  the  United  States  Bankruptcy  Code or any  similar  federal  or  state
insolvency  law,  including  without  limitation a petition  filed by LASIK or a
petition filed by a third party seeking relief against LASIK; and (vi) LASIK has
no intention of filing a petition for relief under the United States  Bankruptcy
Code or any  similar  federal or state  insolvency  law, or of seeking any other
form of creditor relief.

          3.2  Authority and  Compliance.  LASIK has full power and authority to
     enter into this Agreement. LASIK has full power and authority to enter into
     and perform its obligations under each Other Agreement.  No further consent
     or approval is required as a condition to the validity of this Agreement or
     any Other  Agreement.  LASIK is in  compliance  with all  applicable  laws,
     ordinances, statutes, orders, regulations,  judgments, writs, or decrees of
     any governmental entity to which it is subject. ------------------------

          3.3  Binding  Agreement.  This  Agreement  and  each  Other  Agreement
     constitute  valid and legally  binding  obligations of LASIK, in accordance
     with  their  terms,  subject  to  the  applicable  bankruptcy,  insolvency,
     reorganization,  moratorium,  and similar laws affecting  creditors' rights
     generally. -----------------

          3.4 Litigation.  There are no proceedings pending or, to the knowledge
     of LASIK,  threatened before any court or administrative  agency which will
     or may have a material  adverse effect on the financial  condition of LASIK
     or upon LASIK's ability to perform its obligations  under this Agreement or
     any Other Agreement. ----------

          3.5 No Conflicting Agreements. There are no provisions of any existing
     agreement,  mortgage,  indenture or contract  binding on LASIK or affecting
     its  property,  which  would  conflict  with  or in  any  way  prevent  the
     execution,  delivery, or carrying out of the terms of this Agreement or any
     Other Agreement. -------------------------

          3.6  Ownership  of  Assets.  LASIK  has  good  and  full  title to the
     Collateral,  and the Collateral is owned free and clear of liens,  charges,
     claims, security interests, and other encumbrances. -------------------

          3.7 Taxes.  LASIK has filed all tax  returns  required  to be filed by
     LASIK.
                                                    ARTICLE IV
                                   LASIK'S COVENANTS WITH RESPECT TO COLLATERAL

         LASIK  covenants  and  agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

          4.1 Delivery of  Instruments  and/or  Certificates.  Contemporaneously
     herewith,  LASIK  covenants  and agrees to  deliver  to  Secured  Party any
     certificates,  documents,  or  instruments  representing  or evidencing the
     Collateral,  with LASIK's  endorsement thereon and/or accompanied by proper
     instruments   of  transfer   and   assignment   duly   executed  in  blank.
     -------------------------------------------

         4.2 Further Assurances. LASIK will contemporaneously with the execution
hereof and from time to time  thereafter  at its  expense  promptly  execute and
deliver all  further  instruments  and  documents  and take all  further  action
necessary  or  appropriate  or that  Secured  Party may  request in order (i) to
perfect and protect the  security  interest  created or  purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received  by LASIK shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is received by LASIK, together with such instruments of transfer as Secured
Party may request,  shall  immediately be delivered to or deposited with Secured
Party and held by Secured Party as Collateral under the terms of this Agreement.
If the  Additional  Property  received by LASIK and  delivered to Secured  Party
pursuant  to this  Section  shall be shares of stock or other  securities,  such
shares  of  stock  or  other  securities  shall  be duly  endorsed  in  blank or
accompanied by proper  instruments  of transfer and assignment  duly executed in
blank with, if requested by Secured Party,  signatures guaranteed by a member or
member organization in good standing of an authorized Securities Transfer Agents
Medallion  Program,  all in form and substance  satisfactory  to Secured  Party.
Secured Party shall be deemed to have possession of any Collateral in transit to
Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  LASIK  will  not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

          4.5 Liens.  Neither LASIK nor any person acting on LASIK's behalf has,
     or shall have any  right,  power,  or  authority  to and shall not  create,
     incur, or permit to be placed or imposed, upon the Collateral,  any lien of
     any type or nature  whatsoever,  other  than the liens in favor of  Secured
     Party. -----

          4.6 Matters or  Occurrences  Affecting  Collateral or this  Agreement.
     LASIK  will  promptly  notify  Secured  Party  of any  and all  matters  or
     occurrences  that may have a material adverse effect on the status or value
     of the  Collateral or this  Agreement,  including  without  limitation  the
     occurrence of an Event of Default, or an event which, with giving of notice
     or  lapse  of  time,  or  both,  would  constitute  an  Event  of  Default.
     -------------------------------------------------------------

          4.7 Agreements  Pertaining to Collateral.  LASIK will not transfer any
     voting  rights  pertaining  to the  Collateral  to any  person  or  entity.
     -----------------------------------

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
LASIK  will not  consent to or approve  of the  issuance  of (i) any  additional
interests  or  shares  of any  class  of  securities  of such  issuer,  (ii) any
instrument  convertible  voluntarily by the holder thereof or automatically upon
the occurrence or non-occurrence of any event or condition into, or exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.

          4.9  Restrictions  on  Securities.  LASIK  will  not  enter  into  any
     agreement  creating,  or  otherwise  permit to exist,  any  restriction  or
     condition upon the transfer, voting or control of any securities pledged as
     Collateral,  except as consented to in writing by Secured Party.  As to any
     securities  pledged as collateral,  LASIK will not consent to or approve of
     any stock split, reverse stock split, stock dividend, reclassification,  or
     other  similar  act  or   transaction   regarding   the  Interests   unless
     -------------------------- consented to in writing by Secured Party.

                                                     ARTICLE V
                                           LASIK'S AFFIRMATIVE COVENANTS

         Until payment and performance of all  Obligations,  LASIK covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  LASIK  and of any  condition,  event or act  which  comes to its
attention  that  would  or might  have a  material  adverse  effect  on  LASIK's
financial condition.

                                                    ARTICLE VI
                                                NEGATIVE COVENANTS

         Until payment and performance of all  Obligations,  LASIK covenants and
agrees that LASIK will not,  without the prior written  consent of Secured Party
grant, suffer, or permit liens on, or security interests in, the Collateral.


                                                    ARTICLE VII
                                               DEFAULT AND REMEDIES

          7.1 Events of Default.  An Event of Default  (herein so called)  shall
     exist  if  any  one  or  more  of  the   following   events   shall  occur:
     -----------------

          (a) The failure of Debtor to pay any amount  required to be paid under
     the Loan Agreement or any Note (including,  without limitation,  principal,
     interest and fees due thereunder)  within ten (10) calendar days after such
     amount is due;

          (b) The failure of LASIK to pay any  Obligation  described  in Section
     1.2(b)  within ten (10)  calendar  days after such  amount is due (and,  if
     applicable  under  the  terms  of any  contractual  agreement  creating  or
     governing  such  Obligation,  after  the  expiration  of  any  cure  period
     expressly required);

                  (c)      LASIK's breach of a covenant in this Agreement;

          (d) Any  representation  or warranty  made by LASIK in this  Agreement
     shall be false or materially  misleading,  as determined in the  reasonable
     discretion of Secured Party;

          (e) Any  event of  default  shall  occur  under  the terms of the Loan
     Agreement  and shall not be cured  within the time  expressly  provided for
     with respect thereto in the Loan Agreement;

                  (f) If LASIK or Debtor,  or any other party  obligated  to pay
any portion of the Obligations:  (i) becomes  insolvent,  or makes a transfer in
fraud of  creditors,  or makes an assignment  for the benefit of  creditors,  or
admits in  writing  its  inability  to pay its debts as they  become  due;  (ii)
generally is not paying its debts as such debts become due and Secured Party, in
good faith,  determines  that such event or  condition  could lead to a material
impairment  of the  Collateral,  or any part  thereof,  or of any other  payment
security for any of the Obligations;  (iii) has a receiver, trustee or custodian
appointed for, or take possession of, all or substantially  all of the assets of
such  party or any of the  Collateral,  either in a  proceeding  brought by such
party or in a proceeding  brought against such party and such appointment is not
discharged or such possession is not terminated within sixty (60) days after the
effective  date  thereof  or  such  party  consents  to or  acquiesces  in  such
appointment  or  possession;  (iv) files a petition  for relief under the United
States  Bankruptcy  Code  or any  other  present  or  future  federal  or  state
insolvency,  bankruptcy  or  similar  laws  (all  of the  foregoing  hereinafter
collectively called "Applicable  Bankruptcy Law") or an involuntary petition for
relief is filed against such party under any Applicable  Bankruptcy Law and such
involuntary  petition is not  dismissed  within sixty (60) days after the filing
thereof,  or an order  for  relief  naming  such  party  is  entered  under  any
Applicable  Bankruptcy  Law,  or  any  composition,   rearrangement,  extension,
reorganization or other relief of debtors now or hereafter existing is requested
or consented to by such party;  (v) fails to have discharged  within a period of
sixty (60) days any  attachment,  sequestration  or similar writ levied upon, or
any claim against or affecting, any property of such party; or (vi) fails to pay
within ninety (90) days any final money judgment against such party; or

          (g) The  issuer  of any  securities  constituting  Collateral  files a
     petition for relief under any  Applicable  Bankruptcy  Law, an  involuntary
     petition for relief is filed  against any such issuer under any  Applicable
     Bankruptcy Law and such involuntary petition is not dismissed within thirty
     (30) days after the filing thereof,  or an order for relief naming any such
     issuer is entered under any Applicable Bankruptcy Law.

          7.2  Secured  Party's  Remedies.  Upon the  occurrence  of an Event of
     Default:

          (a)  Secured  Party  may  declare  the  Obligations  in  whole or part
     immediately  due and may enforce  payment and  performance  of the same and
     exercise  any rights  under the Texas UCC,  rights and  remedies of Secured
     Party under this Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of LASIK,  either in Secured  Party's  own right or in the name of LASIK
and in the same manner and to the same extent that LASIK might reasonably so act
if this Agreement had not been made: (i) do all things requisite, convenient, or
necessary to enforce the performance and observance of all rights,  remedies and
privileges of LASIK arising from the Collateral, or any part thereof,  including
without limitation compromising,  waiving,  excusing, or in any manner releasing
or discharging  any  obligation of any party to or arising from the  Collateral;
(ii) take possession of the books,  papers,  chattel paper,  documents of title,
and accounts of LASIK, wherever located,  relating to the Collateral;  (iii) sue
or otherwise collect and receive money attributable to the Collateral;  and (iv)
exercise  any other  lawfully  available  powers or  remedies,  and do all other
things which Secured Party deems requisite, convenient or necessary or which the
Secured Party deems proper to protect the Security Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by  applicable  law (LASIK hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name  or as  LASIK's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in  equity,  against  LASIK and all
persons and  corporations  lawfully  claiming by or through or under LASIK.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in any type of offering  which  complies  with, or is exempt from the
registration requirements of, the Securities Act of 1933, and no sale so made in
good faith by Secured Party shall be deemed to be not "commercially  reasonable"
because so made.

          (d) Not in  limitation  of any  other  provision  of  this  Agreement,
     Secured  Party shall have all rights and remedies of a secured  party under
     the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance  with the terms hereof or under the  Contribution  Agreement,  the
Loan Agreement or any Note; (d) then, to or among the amounts of fees,  interest
and  principal  then owing and unpaid in  respect  of the  Obligations,  in such
priority as Secured Party may determine in its discretion; and (e) the remainder
of such  proceeds,  if any,  shall be paid to LASIK.  If such proceeds  shall be
insufficient to discharge the entire  Obligations,  Secured Party shall have any
other available  legal recourse  against LASIK under, or for the performance of,
the Contribution Agreement, the Loan Agreement and any Note, for the deficiency,
together with interest  thereon at the maximum rate permitted  under  applicable
law.

          7.4  Enforcement of  Obligations.  Nothing in this Agreement or in any
     other document or agreement  shall affect or impair the  unconditional  and
     absolute right of Secured Party to enforce the  Obligations as and when the
     same shall become due. --------------------------

                                                   ARTICLE VIII
                                              RIGHTS OF SECURED PARTY

          8.1 Subrogation.  Upon the occurrence of an Event of Default,  Secured
     Party,  at its election,  may subrogate to all of the interest,  rights and
     remedies  of LASIK,  in  respect  to any of the  Collateral  or  agreements
     pertaining thereto. -----------

         8.2 Secured Party  Appointed  Attorney-in-Fact.  LASIK hereby  appoints
Secured Party as attorney-in-fact of LASIK, with full authority in the place and
stead of LASIK and in the name of LASIK,  Secured Party or otherwise,  from time
to time on Secured  Party's  discretion  and upon the  occurrence of an Event of
Default,  to take any action and to execute any  instrument  which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

          8.3  Performance  by Secured  Party.  If LASIK  fails to  perform  any
     agreement contained herein,  Secured Party may itself perform, or cause the
     performance  of, such  agreement,  and the  reasonable  expenses of Secured
     Party  incurred  in  connection  therewith  shall be payable by LASIK under
     Section 8.8. In no event, however,  shall Secured Party have any obligation
     or  duties  whatsoever  to  perform  any  covenant  or  agreement  of LASIK
     contained  herein,  and any such  performance  by  Secured  Party  shall be
     ---------------------------- wholly discretionary with Secured Party.

          8.4 Duties of Secured Party.  The powers  conferred upon Secured Party
     hereunder  are solely to protect its interest in the  Collateral  and shall
     not impose any duty upon it to  exercise  any such  powers.  Except for the
     safe custody of any  Collateral in its  possession  and the  accounting for
     money actually  received by it hereunder,  Secured Party shall have no duty
     as to any Collateral or as to the taking of any necessary steps to preserve
     rights  against prior  parties or any other rights  -----------------------
     pertaining to any Collateral.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations, responsibilities, or duties of LASIK arising in connection with the
Collateral assigned hereunder or otherwise bind Secured Party to the performance
of any obligations respecting the Collateral, it being expressly understood that
Secured  Party shall not be obligated  to perform,  observe,  or  discharge  any
obligation, responsibility, duty, or liability of LASIK in respect of any of the
Collateral,  including without limitation  appearing in or defending any action,
expending  any money or incurring any expense in  connection  therewith.  TO THE
FULLEST  EXTENT  PERMITTED  BY  APPLICABLE  LAW,  LASIK  SHALL AND DOES AGREE TO
INDEMNIFY, PROTECT, DEFEND AND HOLD HARMLESS SECURED PARTY AND ITS SUBSIDIARIES,
AND EACH OF  THEIR  OFFICERS,  DIRECTORS,  REPRESENTATIVES,  AGENTS,  EMPLOYEES,
LENDERS,  SUCCESSORS  AND  ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,
DAMAGES,  LOSSES,  FINES,  PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND
EXPENSES  (INCLUDING COURT COSTS,  ATTORNEY'S FEES AND COST OF INVESTIGATION) OF
ANY NATURE, KIND OR DESCRIPTION OF ANY PERSON OR ENTITY, DIRECTLY OR INDIRECTLY,
ARISING OUT OF,  CAUSED BY OR RESULTING  FROM (IN WHOLE OR IN PART),  ANY ACT OR
OMISSION  OF SECURED  PARTY,  OR ANYONE  ACTING ON BEHALF OF SECURED  PARTY,  IN
CONNECTION  WITH  THE  COLLATERAL,   INCLUDING  WITHOUT  LIMITATION  ANY  MARKET
FLUCTUATIONS  IN THE  COLLATERAL  AS A RESULT  OF  SECURED  PARTY'S  SALE OF, OR
FAILURE TO SELL, THE INTERESTS AT ANY  PARTICULAR  TIME WHEN IT HAS THE RIGHT TO
DO  SO.  THE  FOREGOING  INDEMNITY  SHALL  SURVIVE  THE  EXPIRATION  OR  EARLIER
TERMINATION OF THIS AGREEMENT.

          8.6  Right of  Secured  Party to  Defend  Action  Affecting  Security.
     Secured Party may, at the expense of LASIK, appear in and defend any action
     or proceeding  at law or in equity  purporting  to affect  Secured  Party's
     Security          Interest          under          this          Agreement.
     ----------------------------------------------------------

         8.7 Right of Secured Party to Prevent or Remedy Default. If LASIK shall
fail to perform any of the covenants,  conditions and agreements  required to be
performed and observed by LASIK under any Other Agreement,  or in respect of the
Collateral  (subject to any applicable  default cure period),  Secured Party (a)
may but shall not be obligated to take any action Secured Party deems  necessary
or  desirable  to prevent or remedy any such  default by LASIK or  otherwise  to
protect the Security  Interest,  and (b) shall have the  absolute and  immediate
right to take  possession  of the  Collateral or any part thereof (to the extent
Secured Party has not previously  taken  possession) to such extent and as often
as the Secured Party,  in its sole  discretion,  deems necessary or desirable in
order to prevent or to cure any such  default by LASIK,  or otherwise to protect
the security of this Agreement. Secured Party may advance or expend such sums of
money for the  account of LASIK as Secured  Party in its sole  discretion  deems
necessary for any such purpose.

          8.8  Secured  Party's  Expenses.   All  reasonable  advances,   costs,
     expenses,  charges and attorneys' fees which Secured Party may make, pay or
     incur under any  provision  of this  Agreement  for the  protection  of its
     security or for the enforcement of any of its rights hereunder,  including,
     without limitation,  in foreclosure  proceedings commenced and subsequently
     abandoned. ------------------------

          8.9. Remedies.  No right or remedy herein reserved to Secured Party is
     intended to be exclusive  of any other right or remedy,  but each and every
     such  remedy  shall be  cumulative,  not in lieu of, but in addition to any
     other rights or remedies  given under this Agreement and all other security
     documents.  Any and all of  Secured  Party's  rights  and  remedies  may be
     exercised  from  time to time  and as  often  as such  exercise  as  deemed
     necessary or desirable by Secured Party. --------

         8.10 LASIK's  Waivers.  LASIK waives notice of the  creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.11 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the  Obligations.  LASIK waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
LASIK agrees that  Secured  Party shall have no duty or  obligation  to LASIK to
apply to the Obligations any such other security or proceeds thereof.

                                                    ARTICLE IX
                                                   MISCELLANEOUS

          9.1 Terms Commercially  Reasonable.  The terms of this Agreement shall
     be deemed  commercially  reasonable  within  the  meaning of the Texas UCC.
     -----------------------------


         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to LASIK their  respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

            Secured Party:             1301 Capital of Texas Hwy., Suite C-300
                                       Austin, Travis County, Texas 78746
                                       Attn: President

                  with copy to:        Timothy L. LaFrey, Esq.
                                       Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                       1900 Frost Bank Plaza
                                       816 Congress Avenue
                                       Austin, Texas 78701

                  LASIK:               LASIK Investors, L.L.C.
                                       4800 North 22nd Street
                                       Phoenix, Arizona  85016

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations,  warranties, and agreements of LASIK if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of LASIK.

          9.4 Waiver. No delay of Secured Party in exercising any power or right
     shall operate as a waiver thereof; nor shall any single or partial exercise
     of any power or right  preclude  other or further  exercise  thereof or the
     exercise  of any other  power or right.  No waiver by Secured  Party of any
     right hereunder of any default by LASIK shall be binding upon Secured Party
     unless in writing, and no failure by Secured Party to exercise any power or
     right hereunder or waiver of any default by LASIK ------ shall operate as a
     waiver  of any  other or  further  exercise  of such  right or power of any
     further default.

          9.5 Agreement Continuing. This Agreement shall constitute a continuing
     agreement, applying to all future as well as existing transactions, whether
     or not of the character contemplated at the date of this Agreement,  and if
     all  transactions  between  Secured  Party and LASIK shall be closed at any
     time,  shall be  equally  applicable  to any new  transactions  thereafter.
     --------------------

          9.6 Definitions.  Unless the context indicated otherwise,  definitions
     in the Texas  Business and Commerce  Code ("Texas  UCC") apply to words and
     phrases in this  Agreement;  if Texas UCC definitions  conflict,  Chapter 9
     definitions apply. -----------

          9.7  Miscellaneous.   In  this  Agreement,  whenever  the  context  so
     requires,  the neuter gender  includes the masculine and feminine,  and the
     singular  number  includes  the  plural and vice  versa.  The  headings  of
     paragraphs  herein are inserted  only for  convenience  and shall in no way
     define,  describe  or limit the scope of intent of any  provisions  of this
     Agreement. No change, amendment,  modification,  cancellation, or discharge
     of any provision of this  Agreement  shall be valid unless  consented to in
     ------------- writing by Secured Party.

          9.8 Assignment of Secured Party's  Interest.  Secured Party shall have
     the right to assign  all or any  portion  of its  rights in this  Agreement
     without approval or consent.  LASIK acknowledges that Secured Party intends
     to make a collateral  assignment of its rights under this Agreement for the
     benefit of one or more of its lenders.  LASIK may not assign this Agreement
     or any of its rights or  obligations  hereunder  without the express  prior
     written     consent     of    Secured     Party    in    each     instance.
     --------------------------------------

          9.9 Applicable Laws. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED
     IN ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE APPLICABLE  LAWS
     OF THE UNITED STATES OF AMERICA. ---------------

          9.10 ENTIRE AGREEMENT.  THIS AGREEMENT,  THE LOAN AGREEMENT,  THE NOTE
     AND THE  CONTRIBUTION  AGREEMENT  (AND THE  OTHER  AGREEMENTS  CONTEMPLATED
     THEREIN)  REPRESENT THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE
     CONTRADICTED  BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS,  OR  SUBSEQUENT  ORAL
     AGREEMENTS OF THE PARTIES.  THERE ARE NO UNWRITTEN ORAL AGREEMENTS  BETWEEN
     THE PARTIES. ----------------

                                             [Signature page follows]




<PAGE>


                                SIGNATURE PAGE TO
                                 ASSIGNMENT AND
                               SECURITY AGREEMENT

         EXECUTED this ___ day of September, 1999.

DEBTOR:                                         LASIK Investors, L.L.C.


                                           By:  /s/ Ronald W. Barnet, M.D.
                                                Ronald W. Barnet, M.D., manager


                                           By:  /s/ David D. Dulaney, M.D.
                                                David D. Dulaney, M.D., manager



SECURED PARTY:                                   Prime Medical Operating, Inc.

                                           By: /s/ Cheryl Williams

                                           Name:Cheryl Williams

                                           Title:Treasurer




<PAGE>



                                 PROMISSORY NOTE


Austin, Texas                                                 September 1, 1999



PROMISE TO PAY: For value  received,  the undersigned  Borrower  (whether one or
more) promises to pay to the order of Lender the Principal Amount, together with
interest on the unpaid  balance of such  amount,  in lawful  money of the United
States of America, in accordance with all the terms,  conditions,  and covenants
of this Note and the Loan Documents identified below.

BORROWER:    Prime/BDR Acquisition, L.L.C., a Delaware limited liability company

BORROWER'S ADDRESS FOR NOTICE:        1301 Capital of Texas Highway, Suite C-300
                                      Austin, Texas  78746
                                      Attention: President

LENDER:           Prime Medical Operating, Inc., a Delaware corporation

LENDER'S ADDRESS FOR PAYMENT:        1301 Capital of Texas Highway, Suite C-300,
                                     Austin, Texas 78746
                                     Attention: Chief Financial Officer

PRINCIPAL  AMOUNT:  Ten  Million  Eight  Hundred  Thirty-Five  Thousand  Dollars
                    ($10,835,000)

INTEREST RATE:  Fifteen Percent (15%)

PAYMENT  TERMS:  Interest on the unpaid  balance of this Note is due and payable
quarterly,  beginning September 1, 1999, and continuing  regularly and quarterly
thereafter on or before the first day of March, June, September, and December of
each year, until September 1, 2006 (the "Maturity  Date"),  when the outstanding
principal  balance  and all accrued  interest  shall be due and payable in full.
Interest will be calculated on the unpaid principal  balance.  Each payment will
be  credited  first  to the  accrued  interest  and  then  to the  reduction  of
principal.

LOAN AGREEMENT:  This Note is executed  pursuant to and is governed by the terms
of that certain Loan Agreement dated September 1, 1999, executed by Borrower and
Lender, as amended (collectively, the "Loan Agreement").

1.       INTEREST PROVISIONS:

Rate:  The  principal  balance of this Note from time to time  remaining  unpaid
prior to maturity  shall bear  interest at the  Interest  Rate per annum  stated
above.




<PAGE>



     Maximum Lawful  Interest:  The term "Maximum Lawful Rate" means the maximum
rate of interest and the term "Maximum  Lawful  Amount" means the maximum amount
of interest that is permissible  under  applicable  state or federal law for the
type of loan evidenced by this Note and the other Loan Documents. If the Maximum
Lawful Rate is increased by statute or other  governmental  action subsequent to
the date of this Note,  then the new Maximum  Lawful Rate shall be applicable to
this Note from the  effective  date  thereof,  unless  otherwise  prohibited  by
applicable law.

     Spreading of Interest:  Because of the  possibility  of irregular  periodic
balances of principal or premature payment,  the total interest that will accrue
under this Note  cannot be  determined  in  advance.  Lender  does not intend to
contract for,  charge,  or receive more than the Maximum  Lawful Rate or Maximum
Lawful Amount  permitted by applicable state or federal law, and to prevent such
an occurrence  Lender and Borrower agree that all amounts of interest,  whenever
contracted  for,  charged,  or received by Lender,  with  respect to the loan of
money evidenced by this Note, shall be spread,  prorated,  or allocated over the
full period of time this Note is unpaid,  including the period of any renewal or
extension  of this Note.  If demand  for  payment of this Note is made by Lender
prior to the full stated  term,  the total  amount of interest  contracted  for,
charged,  or received to the time of such demand shall be spread,  prorated,  or
allocated  along with any interest  thereafter  accruing over the full period of
time that this Note thereafter  remains unpaid for the purpose of determining if
such interest exceeds the Maximum Lawful Amount.

     Excess Interest:  At maturity  (whether by acceleration or otherwise) or on
earlier  final  payment of this Note,  Lender shall  compute the total amount of
interest that has been contracted for, charged, or received by Lender or payable
by Borrower under this Note and compare such amount to the Maximum Lawful Amount
that could have been contracted  for,  charged,  or received by Lender.  If such
computation  reflects that the total amount of interest that has been contracted
for,  charged,  or received by Lender or payable by Borrower exceeds the Maximum
Lawful  Amount,  then Lender  shall apply such  excess to the  reduction  of the
principal balance and not to the payment of interest; or if such excess interest
exceeds the unpaid principal balance, such excess shall be refunded to Borrower.
This  provision  concerning  the  crediting or refund of excess  interest  shall
control and take  precedence  over all other  agreements  between  Borrower  and
Lender so that under no circumstances  shall the total interest  contracted for,
charged, or received by Lender exceed the Maximum Lawful Amount.

     Interest After Default:  At Lender's option,  the unpaid principal  balance
shall bear interest after maturity (whether by acceleration or otherwise) at the
"Default Interest Rate." The Default Interest Rate shall be, at Lender's option,
(i) the Maximum  Lawful Rate,  if such  Maximum  Lawful Rate is  established  by
applicable  law; or (ii) the Interest Rate stated on the first page of this Note
plus five (5)  percentage  points,  if no Maximum  Lawful Rate is established by
applicable  law; or (iii) eighteen  percent (18%) per annum; or (iv) such lesser
rate of  interest  as Lender in its sole  discretion  may choose to charge;  but
never more than the Maximum  Lawful Rate or at a rate that would cause the total
interest  contracted for,  charged,  or received by Lender to exceed the Maximum
Lawful Amount.

     Daily  Computation of Interest:  To the extent permitted by applicable law,
Lender at its option will  calculate  the per diem interest rate or amount based
on the actual  number of days in the year (365 or 366, as the case may be),  and
charge that per diem  interest rate or amount each day. In no event shall Lender
compute  the  interest in a manner  that would  cause  Lender to  contract  for,
charge,  or receive  interest  that would exceed the Maximum  Lawful Rate or the
Maximum Lawful Amount

DEFAULT PROVISIONS:

EVENTS OF DEFAULT AND  ACCELERATION  OF MATURITY:  LENDER MAY, AFTER THIRTY (30)
DAYS'  WRITTEN  NOTICE TO BORROWER  AND  BORROWER'S  FAILURE TO CURE WITHIN SUCH
30-DAY  PERIOD  AND  WITHOUT  FURTHER  NOTICE OR DEMAND,  (except  as  otherwise
required  by  statute),  ACCELERATE  THE  MATURITY  OF THIS NOTE AND DECLARE THE
ENTIRE UNPAID PRINCIPAL BALANCE AND ALL ACCRUED INTEREST AT ONCE DUE AND PAYABLE
IF:

     There is default in the payment of any  installment of principal, interest,
or any other sum  required to be paid under the terms of this Note or any of the
Loan Documents; or

     There is a  breach  or  default  (other  than by  Lender  or Prime  Medical
Services,  Inc.)  under this Note or any of the Loan  Documents,  including  any
instrument  securing the payment of this Note or any loan agreement  relating to
the advance of loan proceeds.

WAIVER BY BORROWER: EXCEPT AS PROVIDED IN PARAGRAPH 2(a) HEREOF AND IN ANY OTHER
LOAN  DOCUMENT,  BORROWER  AND ALL OTHER  PARTIES  LIABLE  FOR THIS NOTE  WAIVE,
DEMAND,  NOTICE  OF  INTENT  TO  DEMAND,  PRESENTMENT  FOR  PAYMENT,  NOTICE  OF
NONPAYMENT,  PROTEST,  NOTICE OF PROTEST,  GRACE, NOTICE OF DISHONOR,  NOTICE OF
INTENT TO ACCELERATE MATURITY, NOTICE OF ACCELERATION OF MATURITY, AND DILIGENCE
IN COLLECTION.  EACH MAKER, SURETY,  ENDORSER, AND GUARANTOR OF THIS NOTE WAIVES
AND AGREES TO ONE OR MORE  EXTENSIONS FOR ANY PERIOD OR PERIODS OF TIME, AND ANY
PARTIAL PAYMENTS,  BEFORE OR AFTER MATURITY,  WITHOUT PREJUDICE TO THE HOLDER OF
THIS NOTE. EACH MAKER, SURETY,  ENDORSER, AND GUARANTOR WAIVES NOTICE OF ANY AND
ALL RENEWALS, EXTENSIONS, REARRANGEMENTS, AND MODIFICATIONS OF THIS NOTE.

     Non-Waiver by Lender: Any previous extension of time, forbearance,  failure
to pursue some remedy,  acceptance  of late  payments,  or acceptance of partial
payment by Lender,  before or after  maturity,  does not  constitute a waiver by
Lender of its subsequent  right to strictly  enforce the collection of this Note
according to its terms.

     Other  Remedies  Not  Required:  Lender shall not be required to first file
suit, exhaust all remedies,  or enforce its rights against any security in order
to enforce payment of this Note.

     Joint and Several Liability:  Each Borrower who signs this Note, and all of
the other  parties  liable for the  payment of this  Note,  such as  guarantors,
endorsers,  and sureties,  are jointly and  severally  liable for the payment of
this Note.

     Attorney's  Fees: If Lender requires the services of an attorney to enforce
the payment of this Note or the performance of the other Loan  Documents,  or if
this Note is  collected  through  any  lawsuit,  probate,  bankruptcy,  or other
judicial  proceeding,  Borrower  agrees to pay  Lender  an  amount  equal to its
reasonable  attorney's fees and other collection  costs. This provision shall be
limited by any applicable statutory  restrictions  relating to the collection of
attorney's fees.

3.       MISCELLANEOUS PROVISIONS:

     Subsequent  Holder:  All references to Lender in this Note shall also refer
to any  subsequent  owner  or  holder  of  this  Note by  transfer,  assignment,
endorsement, or otherwise.

     Transfer:  Borrower  acknowledges  and agrees that Lender may transfer this
Note  or  partial   interests  in  the  Note  to  one  or  more  transferees  or
participants,  including without  limitation  transfers  provided for in Section
8.10 of the Loan  Agreement.  Borrower  authorizes  Lender to disseminate to any
such  transferee or  participant or  prospective  transferee or participant  any
information  it has  pertaining to the loan  evidenced by this Note,  including,
without  limitation,  credit  information  on Borrower and any guarantor of this
Note and any of the type of  information  described  in Section 8.10 of the Loan
Agreement.

     Other Parties Liable:  All promises,  waivers,  agreements,  and conditions
applicable  to Borrower  shall  likewise be  applicable  to and binding upon any
other  parties  primarily  or  secondarily  liable for the payment of this Note,
including all guarantors, endorsers, and sureties.

     Successors  and Assigns:  The provisions of this Note shall be binding upon
and  for  the  benefit  of  the  successors,   assigns,  heirs,  executors,  and
administrators of Lender and Borrower.

     No Duty or Special  Relationship:  Borrower acknowledges that Lender has no
duty of good faith to Borrower,  and Borrower  acknowledges  that no  fiduciary,
trust, or other special relationship exists between Lender and Borrower.

     Modifications:  Any  modifications  agreed  to by  Lender  relating  to the
release of liability of any of the parties  primarily or secondarily  liable for
the  payment  of  this  Note,  or  relating  to the  release,  substitution,  or
subordination  of all or part of the  security  for this  Note,  shall in no way
constitute a release of liability  with respect to the other parties or security
not covered by such modification.

     Entire Agreement:  Borrower warrants and represents that the Loan Documents
constitute the entire agreement  between Borrower and Lender with respect to the
loan  evidenced  by this Note and agrees  that no  modification,  amendment,  or
additional  agreement  with  respect  to such loan or the  advancement  of funds
thereunder will be valid and  enforceable  unless made in writing signed by both
Borrower and Lender.

     Borrower's Address for Notice: All notices required to be sent by Lender to
Borrower shall be sent by U.S. Mail, postage prepaid,  to Borrower's Address for
Notice stated on the first page of this Note, until Lender shall receive written
notification from Borrower of a new address for notice.

     Lender's Address for Payment:  All sums payable by Borrower to Lender shall
be paid at Lender's  Address for Payment  stated on the first page of this Note,
or at such other address as Lender shall designate from time to time.

     Business Use:  Borrower warrants and represents to Lender that the proceeds
of this Note will be used solely for business or commercial purposes,  and in no
way will the proceeds be used for personal, family, or household purposes.

     Chapter 15 Not  Applicable:  It is understood  that Chapter 15 of the Texas
Credit Code  relating to certain  revolving  credit loan  accounts and tri-party
accounts is not applicable to this Note.

     APPLICABLE  LAW:  THIS NOTE HAS BEEN  EXECUTED  AND  DELIVERED IN TEXAS AND
SHALL BE CONSTRUED IN ACCORDANCE  WITH THE APPLICABLE LAWS OF THE STATE OF TEXAS
AND THE LAWS OF THE  UNITED  STATES OF AMERICA  APPLICABLE  TO  TRANSACTIONS  IN
TEXAS.

4.       LOAN DOCUMENTS:

This Note.

The Loan Agreement and the Loan Documents as defined therein.

All other  documents  signed in connection  with the Loan  Agreement or the loan
evidenced by this Note, including, without limitation, that certain Contribution
Agreement,  dated  effective  September  1, 1999,  between  and among  Borrower,
Lender,  Prime  Medical  Services,  Inc.,  a  Delaware  corporation,  Prime/BDEC
Acquisition,  L.L.C., a Delaware limited liability  company,  Barnet Dulaney Eye
Center,  P.L.L.C.,  an Arizona  professional  limited liability  company,  LASIK
Investors, L.L.C., a Delaware limited liability company, David D. Dulaney, M.D.,
Ronald W. Barnet,  M.D., and Mark Rosenberg (the  "Contribution  Agreement") and
each  Transaction  Document  (as  such  term  is  defined  in  the  Contribution
Agreement).



                                              [Signature page follows]



<PAGE>



                                EXECUTION PAGE TO
                                 PROMISSORY NOTE


EXECUTED this 1st day of September, 1999.



             BORROWER:

             PRIME/BDR ACQUISITION, L.L.C., a Delaware limited liability company



                                  By: /s/ David D. Dulaney, M.D.

                                  David D. Dulaney, M.D., Manager


<PAGE>

                                 LOAN AGREEMENT

         This Loan Agreement  (this  "Agreement") is entered into as of the 31st
day of January,  2000, by and between Prime  Refractive  Management,  L.L.C.,  a
Delaware limited liability  company,  and Prime  Refractive,  L.L.C., a Delaware
limited liability company.

                                  Definitions:

EFFECTIVE DATE:   January 31, 2000

BORROWER:         Prime Refractive, L.L.C., a Delaware limited liability company

BORROWER'S
ADDRESS:          1301 Capital of Texas Highway, Suite C-300,
                        Austin, Texas  78746

LENDER:           Prime Refractive Management, L.L.C.,
                        a Delaware limited liability company

LENDER'S
ADDRESS:          1301 Capital of Texas Highway, Suite C-300,
                        Austin, Texas  78746

NOTES:

         Working  Capital Note:  Promissory Note (Line of Credit) in the maximum
         principal  amount of $200,000 (the "Working  Capital Maximum  Principal
         Amount")  dated as of January  31,  2000,  executed  by  Borrower,  and
         payable  to the order of  Lender  as  provided  therein  (the  "Working
         Capital Note").

         Development Facility Notes:  Promissory Notes in substantially the form
         attached as Exhibit G2 to the  Contribution  Agreement (as  hereinafter
         defined),  in the aggregate  maximum  original  principal amount not to
         exceed   $29,165,000  (the  "Development   Facility  Maximum  Principal
         Amount"),  executed by  Borrower  and payable to the order of Lender as
         provided therein (the "Development Facility Notes").  Collectively, the
         Working Capital Notes and the  Development  Facility Notes are referred
         to herein as the "Notes."

SECURITY AGREEMENTS:  All documents,  agreements and instruments  hereinafter or
herewith  executed by Borrower,  LASIK  Investors,  L.L.C.,  a Delaware  limited
liability  company ("LASIK") or any Target Center securing this Agreement or the
obligations under any of the Notes.

LOAN  DOCUMENTS:  This  Agreement,  the Working  Capital Note,  the  Development
Facility Notes, the Security  Agreements,  and all other documents,  agreements,
and instruments now or hereafter existing,  evidencing,  securing,  or otherwise
relating to this Agreement and any transactions  contemplated by this Agreement,
as any of the foregoing items may be modified or supplemented from time to time.

INDEBTEDNESS:  All present and future indebtedness,  obligations and liabilities
of Borrower to Lender,  all present  and future  indebtedness,  obligations  and
liabilities  of any Target Center to Lender,  and all renewals,  extensions  and
modifications  of either of the foregoing,  arising  pursuant to any of the Loan
Documents  and all  interest  accruing  thereon,  and  all  other  fees,  costs,
expenses, charges and attorneys' fees payable, and covenants performable,  under
any of the Loan Documents (including without limitation this Agreement).

DEFINED  TERMS:  Terms not  otherwise  defined  herein  shall  have the  meaning
provided in that certain  Contribution  Agreement dated  effective  September 1,
1999, by and among Barnet Dulaney Eye Center,  P.L.L.C., David D. Dulaney, M.D.,
Ronald W. Barnet, M.D., Mark Rosenberg,  Prime Medical Services,  Inc. ("PMSI"),
Prime Medical Operating,  Inc., Borrower,  LASIK, Prime/BDR Acquisition,  L.L.C.
and Prime/BDEC  Acquisition,  L.L.C. (as amended by that certain First Amendment
to  Contribution  Agreement  dated as of January 31, 2000,  among the  foregoing
parties,  the  "Contribution  Agreement").  For the  purposes  hereof  the terms
"Target  Centers"  and "Target  Center"  shall have the meaning set forth in the
Contribution  Agreement,  but shall  include,  upon the  acquisition of a Target
Center by Borrower or any subsidiary or affiliate of Borrower, the subsidiary or
affiliate utilized to make such acquisition.

SUBORDINATION:  Certain liens arising in connection with this Agreement in favor
of Lender are  subordinate  to liens in favor of lenders under that certain Loan
Agreement for a $14,000,000  advancing term loan (as  hereinafter  supplemented,
modified,  or replaced,  the  "$14,000,000  Facility"),  entered into by Secured
Party, Bank of America,  N.A., as  administrative  agent,  BankBoston,  N.A., as
documentation agent and such lenders.

                                   AGREEMENT:

         Borrower has requested from Lender the credit accommodations  described
below, and Lender has agreed to provide such credit  accommodations on the terms
and conditions contained herein. Therefore, for good and valuable consideration,
the receipt and sufficiency of which Lender and Borrower acknowledge, Lender and
Borrower hereby agree as follows:

                                    ARTICLE I

                            THE WORKING CAPITAL LOAN

         1.1 The Working Capital Loan. Lender agrees to lend and Borrower agrees
to borrow an amount not to exceed the Working Capital Maximum  Principal  Amount
on the terms and conditions set forth herein (the "Working  Capital Loan").  The
Working Capital Loan will be evidenced by the Working Capital Note.

         1.2  Revolving  Line of  Credit.  Subject to and in  reliance  upon the
terms, conditions,  representations and warranties hereinafter set forth, Lender
agrees to make advances (the "Working  Capital  Advances") to Borrower from time
to time during the period from the Effective Date to and including  September 1,
2000 (the  "Maturity  Date"),  in an aggregate  amount not to exceed the Working
Capital Maximum  Principal  Amount.  Each Working Capital Advance must be either
$10,000 or a higher integral multiple of $10,000.  Funds borrowed and repaid may
be reborrowed,  so long as all conditions  precedent to Working Capital Advances
are met.  The purpose of the  Working  Capital  Advances is to provide  funds to
Borrower  for  working  capital  and for  other  general  business  purposes  of
Borrower.

         1.3 Interest and  Repayment.  Borrower  shall pay the aggregate  unpaid
principal amount of all Working Capital Advances in accordance with the terms of
the Working Capital Note evidencing the indebtedness resulting from such Working
Capital  Advances.  Interest on the Working  Capital  Advances  shall be due and
payable in the manner and at the times set forth in the  Working  Capital  Note,
with final maturity of the Working  Capital Note being on or before the Maturity
Date.

         1.4 Making Advances.  Each Working Capital Advance shall be made within
two business days of written notice (or telephonic  notice confirmed in writing)
given by noon  (Austin,  Texas time) on a business  day of Lender by Borrower to
Lender  specifying  the amount and date thereof  (which may be the same business
day) and if sent by wired funds, at Lender's option, the wiring  instructions of
the deposit  account of Borrower to which such Working  Capital Advance is to be
deposited.

         1.5  Payments  and  Computations.  Borrower  shall  make  each  payment
hereunder and under the Working Capital Note on the day when due in lawful money
of the United  States of America to Lender at  Lender's  Address  for Payment in
same day funds. All repayments of principal on the Working Capital Note shall be
in a minimum  amount of $1,000,  or a higher  integral  multiple of $1,000.  All
computations  of  interest  shall be made by Lender  on the basis of the  actual
number of days  (including the first day but excluding the last day) in the year
(365 or 366,  as the  case  may be)  elapsed,  but in no  event  shall  any such
computation  result in an amount  of  interest  that  would  cause the  interest
contracted for, charged or received by Lender to be in excess of the amount that
would be payable at the Highest Lawful Rate, as herein defined.

                                   ARTICLE II

                         THE DEVELOPMENT FACILITY LOANS

         2.1 The Development Facility.  Subject to the terms of the Contribution
Agreement and the terms, conditions,  representations and warranties hereinafter
set  forth,  Lender  agrees  to lend  Borrower  from time to time,  the  amounts
necessary to acquire or develop Target  Centers,  in an aggregate  amount not to
exceed the Development  Facility  Maximum  Principal Amount  (collectively,  the
"Development Facility Loans").

         2.2 Development  Facility Loans.  Each  Development  Facility Loan will
finance  up to 100% of the  purchase  price  (or  development  cost) of a Target
Center being acquired (or developed) by Borrower.  The parties  acknowledge that
the grant of any Development Facility Loan does not create any obligation on the
part of Lender to extend further Development Facility Loans. Additionally,  each
Development  Facility Loan is subject in all respects to Lender  obtaining prior
written  approval  from the lenders under (but only if such approval is required
under)  either the  $14,000,000  Facility or that certain Loan  Agreement  for a
$86,000,000  revolving credit loan entered into by PMSI, Bank of America,  N.A.,
as  administrative  agent,  BankBoston,  N.A., as documentation  agent and other
lenders  named  therein and the  execution  and  delivery of such  documents  by
Borrower as may be required under the Contribution Agreement,  this Agreement or
any  Transaction   Document  (as  such  term  is  defined  in  the  Contribution
Agreement).  Pursuant to the Contribution  Agreement,  each Development Facility
Loan must be (a) evidenced by a separate  Development  Facility Note executed by
Borrower,  (b)  secured by all of LASIK's  ownership  interest  in  Borrower  as
evidenced by an  Assignment  and Security  Agreement  between  Lender and LASIK,
dated as of the date of this  Agreement,  and (c)  accompanied by Assignment and
Security  Agreements  executed by Borrower in the form attached as Exhibit G1 to
the Contribution Agreement.  In addition, if Borrower is acquiring,  directly or
indirectly,   a  one  hundred   percent  (100%)  interest  in  a  Target  Center
(hereinafter  referred to as a "100% Target Center"),  Borrower shall cause such
Target Center to execute a security agreement,  acceptable in form and substance
to  Lender,  granting  to Lender or one of  Lender's  subsidiaries  the  highest
available priority security interest in all of the assets of such Target Center.

         2.3 Interest and  Repayment.  Borrower and Target  Center shall pay the
unpaid principal amount under each Development  Facility Note in accordance with
the terms of the respective  Development Facility Note. Payments of interest and
principal  on each  Development  Facility  Note shall be due and  payable in the
manner and at the times set forth in the respective Development Facility Note.

                                   ARTICLE III
      CONDITIONS TO WORKING CAPITAL ADVANCES AND DEVELOPMENT FACILITY LOANS

         3.1  Conditions  Precedent  to Initial  Working  Capital  Advance.  The
obligation of Lender to make its initial  Working  Capital Advance is subject to
the condition  precedent that Lender shall have received on or before the day of
such  Working  Capital  Advance  the  following,  each  in  form  and  substance
satisfactory  to Lender and properly  executed by Borrower or other  appropriate
parties:  (a) the Working  Capital Note duly executed by Borrower,  and (b) such
other documents,  opinions,  certificates and evidences as Lender may reasonably
request.

         3.2 Conditions  Precedent to Each Working  Capital  Advance/Development
Facility Loan. In addition to the conditions  precedent stated elsewhere herein,
Lender  shall  not be  obligated  to make any  Working  Capital  Advance  or any
Development Facility Loan unless:

                  (a) the representations and warranties contained in Article IV
         are true and correct in all material  respects on and as of the date of
         such Working  Capital  Advance or Development  Facility Loan, as though
         made on and as of such date with such changes therein;

                  (b) on the date of the Working  Capital Advance or Development
         Facility Loan, no Event of Default,  and no event which, with the lapse
         of time or  notice  or both,  could  become  an Event of  Default,  has
         occurred and is continuing;

               (c)  there  shall  have  been  no  material  adverse  change,  as
          determined  by Lender in its  reasonable  judgment,  in the  financial
          condition or business of Borrower;

               (d) there has been no breach  or  threatened  breach by  Borrower
          under the Contribution  Agreement or any Transaction Document (as such
          term is defined in the Contribution Agreement);

(e)      with respect to each Development  Facility Loan,  Borrower executes the
         respective   Development   Facility  Note  and  Borrower   executes  an
         Assignment and Security Agreement in the form attached as Exhibit G1 to
         the  Contribution  Agreement,  and  otherwise  in  form  and  substance
         acceptable to Lender  wherein  Lender is granted a first lien perfected
         security  interest in all of  Borrower's  or  Borrower's  subsidiaries'
         ownership  interest  in  the  Target  Center  and  related  acquisition
         documents;

(f)      LASIK shall have acknowledged in writing its prior grant to Lender of a
         first  lien  perfected  security  interest  (subordinate  only to liens
         granted  as of the  date of this  Agreement  by  LASIK  in favor of the
         lenders  under the  $14,000,000  Facility) in all of LASIK's  ownership
         interest in Borrower, evidenced by that certain Assignment and Security
         Agreement  between  LASIK  and  Borrower  dated  as of the date of this
         Agreement, and LASIK shall be in compliance with all of its obligations
         thereunder;

                  (g) if  Borrower  is  using  a  Development  Facility  Loan to
         acquire,  directly or indirectly,  a 100% Target Center, Borrower shall
         cause such Target Center to execute a security agreement, acceptable in
         form and  substance  to Lender,  granting  to Lender or one of Lender's
         subsidiaries the highest available priority security interest in all of
         the assets of such Target Center; and

                  (h) Lender shall have received such other approvals, opinions,
         documents,  certificates or evidences as Lender may reasonably  request
         (in form and substance reasonably satisfactory to Lender). Each request
         for an Working  Capital  Advance or Development  Facility Loan shall be
         deemed a representation by Borrower that the conditions of this Section
         3.2 have been met.

                                   ARTICLE IV

                    BORROWER'S REPRESENTATIONS AND WARRANTIES

         Borrower represents and warrants to Lender as follows:

         4.1 Good Standing. Borrower is a duly formed limited liability company,
duly  organized  and in good  standing,  under the laws of Delaware  and has the
power to own its property and to carry on its business in each  jurisdiction  in
which Borrower operates.

         4.2 Authority and Compliance.  Borrower has full power and authority to
enter into this  Agreement,  to make the  borrowing  hereunder,  to execute  and
deliver  the Loan  Documents  and to incur the  indebtedness  described  in this
Agreement,  all of which has been duly  authorized  by all proper and  necessary
action of its managers and members. No further consent or approval of any public
authority is required as a condition to the validity of any Loan  Document,  and
Borrower is in compliance with all laws and regulatory  requirements to which it
is subject.

         4.3 Binding  Agreement.  This  Agreement and other Loan  Documents when
issued and delivered  pursuant hereto for value received will constitute,  valid
and legally binding obligations of Borrower in accordance with their terms.

         4.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Borrower,  threatened before any court or administrative agency which will or
may have a material  adverse effect on the financial  condition or operations of
Borrower or any  subsidiary,  except as disclosed to Lender in writing  prior to
the  date  of  this  Agreement.  To the  knowledge  of  Borrower,  there  are no
proceedings pending or threatened against any Target Center.

         4.5 No  Conflicting  Agreements.  There are no provisions of Borrower's
organizational documents and no provisions of any existing agreement,  mortgage,
indenture or contract binding on Borrower or affecting its property, which would
conflict with or in any way prevent the execution,  delivery, or carrying out of
the terms of the Loan Documents.

         4.6  Ownership  of  Assets.  Borrower  will at all times  maintain  its
tangible  property,  real and  personal,  in good order and repair  taking  into
consideration reasonable wear and tear.

         4.7 Taxes. All income taxes and other taxes due and payable through the
date of this Agreement have been paid prior to becoming delinquent.

                                    ARTICLE V

                        BORROWER'S AFFIRMATIVE COVENANTS

         So long as Borrower may borrow under this  Agreement  and until payment
in full of the Working  Capital Note and all  Development  Facility  Notes,  and
performance of all other obligations of Borrower and Target Centers hereunder or
thereunder, Borrower covenants and agrees to do the following:

         5.1      Financial Statements.
                  --------------------

                  (a)  Maintain,  and cause each Target  Center to  maintain,  a
         system of  accounting  satisfactory  to Lender and in  accordance  with
         generally accepted accounting principles consistently applied, and will
         permit  Lender's  officers or authorized  representatives  to visit and
         inspect  Borrower's  or  Target  Center's  books of  account  and other
         records  at such  reasonable  times and as often as Lender  may  desire
         during office hours and after  reasonable  notice to Borrower,  and pay
         the  reasonable  fees and  disbursements  of any  accountants  or other
         agents of Lender selected by Lender for the foregoing purposes.  Unless
         written notice of another location is given to Lender, Borrower's books
         and records will be located at Borrower's Address.

                  (b)  Furnish  to  Lender  year end  financial  statements,  of
         Borrower and each Target Center,  to include  balance sheet,  operating
         statement  and  surplus  reconciliation,  together  with  an  officer's
         certificate of compliance with this Agreement including computations of
         all quantitative covenants, within 90 days after the end of each annual
         accounting period.

                  (c)  Furnish  to Lender  quarterly  financial  statements,  of
         Borrower and each Target  Center,  to include  balance sheet and profit
         and  loss  statement,   together  with  an  officer's   certificate  of
         compliance   with  this  Agreement   including   computations   of  all
         quantitative  covenants,  within  45  days  of  the  end of  each  such
         accounting period.

                  (d) With each balance sheet delivered under subsections (b) or
         (c) of this Section 5.1, an aging of all Accounts Receivable.

                  (e) Promptly provide Lender with such additional  information,
         reports or statements  respecting the business operations and financial
         condition of Borrower or any Target  Center,  as Lender may  reasonably
         request from time to time.

         5.2  Insurance.  Maintain,  and cause each Target  Center to  maintain,
insurance  with  responsible  insurance  companies  on  such  of its  respective
properties,  in such amounts and against such risks as is customarily maintained
by similar businesses operating in the same vicinity,  specifically to include a
policy  of fire  and  extended  coverage  insurance  covering  all  assets,  and
liability  insurance,  all  to be  with  such  companies  and  in  such  amounts
satisfactory  to Lender and to contain a mortgage  clause  naming  Lender as its
interest may appear. Evidence of such insurance will be supplied to Lender.

         5.3 Existence and Compliance. Maintain, and cause each Target Center to
maintain,  its  organizational  existence  in good  standing and comply with all
laws,  regulations and governmental  requirements  applicable to it or to any of
its property,  business operations and transactions.  Borrower further agrees to
provide Lender with copies of all instruments filed with the Delaware  Secretary
of State amending and/or renewing Borrower's certificate of formation.

         5.4 Adverse Conditions or Events.  Promptly advise Lender in writing of
any  condition,  event or act which comes to its  attention  that would or might
materially  affect  Borrower's  or  any  Target  Center's  financial  condition,
Lender's  rights under this Agreement or any of the Loan  Documents,  and of any
litigation filed against Borrower or to its knowledge against any Target Center.

         5.5      Taxes.  Pay all taxes as they become due and payable.
                  -----

         5.6  Maintenance.  Maintain,  and cause each Target Center to maintain,
all of its respective tangible property in good condition and repair, reasonable
wear  and  tear  excepted,  and make all  necessary  replacements  thereof,  and
preserve and maintain all licenses, privileges, franchises, certificates and the
like necessary for the operation of its business.

         5.7  Application  of  Earnings.  Except as  expressly  contemplated  in
Section 4.3(e) of the  Contribution  Agreement,  pay all available  funds toward
repayment  of the  Working  Capital  Note and any  Development  Facility  Notes,
regardless  of whether  payment of such  amounts  exceeds the  minimum  required
payments under the Working Capital Note and the Development Facility Notes.

                                   ARTICLE VI

                          BORROWER'S NEGATIVE COVENANTS

         So long as Borrower may borrow under this  Agreement  and until payment
in full of the Working  Capital Note and all  Development  Facility  Notes,  and
performance of all other  obligations of Borrower or Target Center  hereunder or
thereunder, Borrower will not, and will cause each of the Target Centers to not,
without the prior written consent of Lender:

         6.1  Transfer  of Assets.  Enter into any merger or  consolidation,  or
sell,  lease,  assign,  or otherwise dispose of or transfer any assets except in
the normal course of its business.

         6.2 Change in Ownership or Structure.  Dissolve or liquidate;  become a
party to any merger or consolidation;  reorganize as a professional corporation;
acquire by purchase,  lease or otherwise all or substantially  all of the assets
or capital stock of any corporation or other entity; or sell,  transfer,  lease,
or otherwise  dispose of all or any substantial part of its respective  property
or assets or business.

         6.3 Liens.  From and after the date  hereof  grant,  suffer,  or permit
liens on or security interests in its respective assets, or fail to promptly pay
all lawful  claims,  whether  for labor,  materials,  or  otherwise,  except for
purchase  money  security  interests  arising  in  the  ordinary  course  of its
respective business.

         6.4 Loans.  Make any loans,  advances or investments to or in any joint
venture,  corporation or other entity, except for the purchase of obligations of
Lender or U.S.  Government  obligations  or the  purchase  of  federally-insured
certificates of deposit.

         6.5 Borrowings. Except for borrowing or incurring open accounts payable
to unaffiliated third parties in the ordinary course of business, create, incur,
assume,  or liable in any  manner  for any  indebtedness  (for  borrowed  money,
deferred  payment  for the  purchase  of assets,  lease  payments,  as surety or
guarantor of the debt of another,  or otherwise)  other than to Lender in excess
of $25,000 without Lender's prior written consent.

         6.6  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

     6.7 Equity  Redemptions  or  Restructurings.  Apply any of its  property or
assets to the purchase,  retirement or redemption of any of its equity interests
or in any way amend its capital structure.

         6.8 Character of Business.  Change the general character of business as
conducted at the date hereof,  or engage in any type of business not  reasonably
related to its business as presently and normally conducted.

                                   ARTICLE VII

                     EVENTS OF DEFAULT; NOTICE; ACCELERATION

         7.1  Events  of  Default.  If one or more of the  following  events  of
default  shall occur and  continue  after  thirty (30) days'  written  notice to
Borrower,  all outstanding principal plus unpaid interest of the Working Capital
Note and each Development  Facility Note, and any other indebtedness of Borrower
to Lender,  shall  automatically be due and payable immediately and Lender shall
have no further obligation to fund under this Agreement.

                  (a) There shall be any breach or default  shall be made in the
         payment of any  installment  of principal or interest  upon the Working
         Capital Note or any  Development  Facility Note,  when due and payable,
         whether at maturity or otherwise; or

               (b) There  shall be any breach or default  (other than by Lender,
          Prime Medical Operating,  Inc. or Prime Medical Services,  Inc.) under
          any Loan Document,  the  Contribution  Agreement,  or any  Transaction
          Document  (other than those  certain  Consulting  Agreements  with Dr.
          Dulaney,  Dr.  Barnet and Mark  Rosenberg as required  pursuant to the
          Contribution  Agreement),  or  any  other  certificate,  agreement  or
          document contemplated hereby or thereby; or

                  (c) Any  representation  or  warranty  of  Borrower  contained
         herein or in any financial  statement,  certificate,  report or opinion
         submitted to Lender in connection  with the Working Capital Loan or any
         Development  Facility Loan, or by Borrower pursuant to the requirements
         of this Agreement,  shall prove to have been incorrect or misleading in
         any material respect when made; or

                  (d) Any judgment  against  Borrower or any attachment or other
         levy  against  the  property  of  Borrower  with  respect  to  a  claim
         materially   affecting  Borrower's  financial  status  remains  unpaid,
         unstayed on appeal,  undischarged,  not bonded or not  dismissed  for a
         period of 30 days; or

               (e) The bankruptcy, death, or dissolution of any guarantor of the
          Indebtedness; or

                  (f) Borrower makes an assignment for the benefit of creditors,
         admits in writing  its  inability  to pay its debts  generally  as they
         become due, files a petition in bankruptcy, is adjudicated insolvent or
         bankrupt,  petitions or applies to any tribunal for any receiver or any
         trustee  of  Borrower  or any  substantial  part  of  their  respective
         property,   commences  any  action   relating  to  Borrower  under  any
         reorganization,  arrangement,  readjustment  of  debt,  dissolution  or
         liquidation  law  or  statute  of  any  jurisdiction,  whether  now  or
         hereafter in effect, or if there is commenced against Borrower any such
         action,  or Borrower by any act indicates its consent to or approval of
         any trustee for Borrower or any  substantial  part of its property,  or
         suffers any such receivership or trustee to continue undischarged.

         7.2  Lender's  Remedies.  Upon the  occurrence  of an Event of Default,
Lender,  without notice of any kind,  except for any notice  required under this
Agreement or any other Loan Document, may, at Lender's option: (i) terminate its
obligation to fund any Working Capital Advance or any Development  Facility Loan
hereunder;  (ii) declare the Indebtedness,  in whole or in part, immediately due
and payable;  and/or (iii)  exercise any other rights and remedies  available to
Lender under this Agreement, any other Loan Document, or applicable laws; except
that upon the occurrence of an Event of Default described in subsection  7.1(f),
all the Indebtedness  shall  automatically  be immediately due and payable,  and
Lender's  obligation  to fund any  Working  Capital  Advance or any  Development
Facility Loan hereunder  shall  automatically  terminate,  without notice of any
kind (including  without limitation notice of intent to accelerate and notice of
acceleration) to Borrower or to any Target Center,  guarantor,  or to any surety
or endorser of any of the Notes, or to any other person.  Borrower,  each Target
Center,  and each guarantor,  surety,  and endorser of any of the Notes, and any
and all other parties  liable for the  Indebtedness  or any part thereof,  waive
demand,  notice  of  intent  to  demand,  presentment  for  payment,  notice  of
nonpayment,  protest,  notice of protest,  grace, notice of dishonor,  notice of
intent to accelerate maturity, notice of acceleration of maturity, and diligence
in collection.

         7.3 Right of Set-Off. Borrower hereby authorizes Lender, to the maximum
extent permitted under and in accordance with applicable laws, at any time after
the occurrence of an Event of Default which  continues  uncured,  to set-off and
apply  any and all  deposits,  funds or  assets at any time held and any and all
other  indebtedness  at any time  owing by  Lender  to or for the  credit or the
account of  Borrower  against  any and all  Indebtedness,  whether or not Lender
exercises  any  other  right  or  remedy  hereunder  and  whether  or  not  such
Indebtedness are then matured.

                                  ARTICLE VIII

                          GENERAL TERMS AND CONDITIONS

         8.1  Notices.  All  notices,  demands,  requests,  approvals  and other
communications  required or permitted hereunder shall be in writing and shall be
deemed to have been given when (a) presented  personally,  or (b) three (3) days
after  deposited in a regularly  maintained mail receptacle of the United States
Postal Service,  postage prepaid,  certified,  return receipt requested,  or (c)
upon receipt of confirmation after sending by facsimile transmission,  addressed
to  Borrower  or  Lender,  as the case may be, at the  respective  addresses  or
facsimile  number for notice set forth on the first page of this  Agreement,  or
such other  address or  facsimile  number as Borrower or Lender may from time to
time designate by written notice to the other.

         8.2 Entire Agreement and  Modifications.  The Loan Documents,  together
with the Contribution Agreement and Transaction Documents, constitute the entire
understanding  and  agreement  between  the  undersigned  with  respect  to  the
transactions  arising  in  connection  with  the  Working  Capital  Loan and the
Development   Facility   Loans,   and   supersede  all  prior  written  or  oral
understandings and agreements  between the undersigned in connection  therewith.
No provision  of this  Agreement  or the other Loan  Documents  may be modified,
waived,  or terminated  except by  instrument  in writing  executed by the party
against whom a  modification,  waiver,  or termination is sought to be enforced,
and, in the case of Lender, executed by a Vice President or higher level officer
of Lender.

         8.3 Severability. In case any of the provisions of this Agreement shall
for  any  reason  be  held  to  be  invalid,  illegal,  or  unenforceable,  such
invalidity, illegality, or unenforceability shall not affect any other provision
hereof,  and this Agreement shall be construed as if such invalid,  illegal,  or
unenforceable provision had never been contained herein.

         8.4  Cumulative  Rights  and No  Waiver.  Lender  shall have all of the
rights and remedies  granted in the Loan  Documents  and  available at law or in
equity,  and these  same  rights and  remedies  shall be  cumulative  and may be
pursued separately,  successively, or concurrently against Borrower, at the sole
discretion of Lender.  Lender's  delay in exercising any right shall not operate
as a waiver thereof,  nor shall any single or partial  exercise by Lender of any
right preclude any other or future exercise thereof or the exercise of any other
right.  Any of Borrower's  covenants and  agreements may be waived by Lender but
only in  writing  signed by an  authorized  officer of Vice  President  level or
higher of Lender or any subsequent  owner or holder of any of the Notes.  Except
as otherwise  expressly  provided in this  Agreement  and in any Note,  Borrower
expressly waives any presentment,  demand, protest, notice of default, notice of
intent  to  accelerate,  notice  of  acceleration,  notice  of  intent to demand
payment,  or other notice of any kind. No notice to or demand on Borrower in any
case shall, of itself, entitle Borrower to any other or further notice or demand
in similar or other circumstances.  No delay or omission by Lender in exercising
any  power  or  right  hereunder  shall  impair  any  such  right or power or be
construed  as a waiver  thereof,  or the  exercise  of any other  right or power
hereunder.

         8.5  Form  and  Substance.  All  documents,   certificates,   insurance
policies,  and other items required  under this Agreement to be executed  and/or
delivered to Lender shall be in form and substance  reasonably  satisfactory  to
Lender.

         8.6 Limitation on Interest: Maximum Rate. Lender and Borrower intend to
contract in strict  compliance  with  applicable  usury law from time to time in
effect.  To effectuate this intention,  Lender and Borrower  stipulate and agree
that none of the terms and provisions of any Note and any other  agreement among
such parties, whether now existing or arising hereafter, shall ever be construed
as a contract to pay interest for the use,  forbearance or detention of money in
excess of the Maximum Rate. If, from any possible  construction of any document,
interest would otherwise be payable to Lender in excess of the Maximum Rate, any
such  construction  shall be subject to the  provisions of this Section and such
document  shall be  automatically  reformed and the  interest  payable to Lender
shall be  automatically  reduced to the Maximum Rate permitted under  applicable
law,  without the  necessity of the  execution of any amendment or new document.
Neither  Borrower,  endorsers or other persons now or hereafter  becoming liable
for payment of any portion of the  principal  or interest of any Note shall ever
be liable for any  unearned  interest on the  principal  amount or shall ever be
required  to pay  interest  thereon  in excess of the  Maximum  Rate that may be
lawfully  charged under  applicable law from time to time in effect.  Lender and
any subsequent  holder of any Note expressly  disavow any intention to charge or
collect  unearned  or  excessive  interest  or finance  charges in the event the
maturity of any Note, is accelerated. If the maturity of any Note is accelerated
for any reason, whether as a result of a default under any Note, or by voluntary
prepayment,  or otherwise,  any amounts constituting interest, or adjudicated as
constituting  interest,  which  are  then  unearned  and  have  previously  been
collected  by Lender or any  subsequent  holder of any Note  shall be applied to
reduce the principal balance thereof then outstanding, or if such amounts exceed
the unpaid  balance of principal,  the excess shall be refunded to Borrower (and
Target Center,  as applicable).  In the event Lender or any subsequent holder of
any Note ever receives, collects or applies as interest any amounts constituting
interest or adjudicated as constituting  interest which would otherwise increase
the  interest to an amount in excess of the amount  permitted  under  applicable
law,  such amount  which  would be  excessive  interest  shall be applied to the
reduction of the unpaid  principal  balance of such Note,  and, if the principal
balances of such Note is paid in full,  any  remaining  excess  shall be paid to
Borrower (and Target Center, as applicable).  In determining  whether or not the
interest  paid or payable under the specific  contingencies  exceeds the Maximum
Rate allowed by applicable law, Borrower and Lender shall, to the maximum extent
permitted under applicable law, (i) characterize any non-principal payment as an
expense,  fee or  premium,  rather  than as  interest;  (ii)  exclude  voluntary
prepayments  and the effect  thereof;  (iii)  amortize,  prorate,  allocate  and
spread,  in equal  parts,  the total  amount of interest  throughout  the entire
contemplated  term of the applicable Note (as it may be renewed and extended) so
that the interest rate is uniform  throughout  the entire term of such Note. The
terms and  provisions of this section  shall  control and supersede  every other
provision of all existing and future agreements between Lender and Borrower (and
Target Center, as applicable).  As used in this Agreement,  "Maximum Rate" means
the maximum non-usurious interest rate that at any time or from time to time may
be contracted for, taken, reserved,  charged or received on the unpaid principal
or accrued past due interest  under  applicable  law and may be greater than the
applicable  rate,  the parties hereby  stipulating  and agreeing that Lender may
contract for, take,  reserve,  charge or receive interest up to the Maximum Rate
without penalty under any applicable law; and "applicable law" means the laws of
the State of Texas or the laws of the United States of America,  whichever  laws
allow the greater interest,  as such laws now exist or may be changed or amended
or come into effect in the future.  In the event  applicable law provides for an
interest  ceiling under  Chapter One of Title 79, Texas  Revised Civil  Statutes
Annotated, as amended, that ceiling shall be the indicated rate ceiling, subject
to any right  Lender may have in the future to change the method of  determining
the Maximum Rate.

     8.7 Third Party Beneficiary.  Borrower  acknowledges that the lenders under
the $14,000,000 facility are third party beneficiaries to this Agreement. Except
for the preceding sentence, this Agreement is for the sole benefit of Lender and
Borrower and is not for the benefit of any third party.

         8.8  Borrower  In  Control.  In no  event  shall  Lender's  rights  and
interests  under the Loan Documents be construed to give Lender the right to, or
be deemed to indicate that Lender is in control of the  business,  management or
properties  of  Borrower  or any  Target  Center  or has  power  over the  daily
management  functions  and  operating  decisions  made by Borrower or any Target
Center.

         8.9 Use of Financial and Other Information. Borrower agrees that Lender
shall be  permitted  to  investigate  and  verify  the  accuracy  of any and all
information furnished to Lender in connection with the Loan Documents, including
without limitation financial  statements,  and to disclose such information,  or
provide  copies of such  information,  to  representatives  appointed by Lender,
including  independent  accountants,  agents,  attorneys,  asset  investigators,
appraisers   and  any  other  persons   deemed   necessary  by  Lender  to  such
investigation.

         8.10  Collateral  Assignment of Loan  Documents.  Lender shall have the
right to  collaterally  assign all of its rights  under this  Agreement  and the
other Loan Documents to the third party beneficiaries  described in Section 8.7.
Lender shall have the right to disclose in confidence such financial information
regarding  Borrower as may be  necessary  to  complete  any such  assignment  or
attempted  assignment,  including without limitation,  all financial statements,
projections,  internal memoranda,  audits, reports, payment history,  appraisals
and any and all other  information and  documentation in Lender's files relating
to Borrower.  This  authorization  shall be irrevocable in favor of Lender,  and
Borrower  waives any claims  against Lender or the party  receiving  information
from Lender  regarding  disclosure of information in Lender's files, and further
waive any  alleged  damages  which may  result  from such  disclosure.  Borrower
acknowledges  that Lender intends to make a collateral  assignment of its rights
under this  Agreement  and the Loan  Documents for the benefit of one or more of
its or its  parent  company's  lenders  and will not be  authorized  to amend or
modify this  Agreement  or the Loan  Documents,  or grant  waivers of any of its
rights  thereunder  without  the prior  written  consent  of some or all of such
lenders.

         8.11 Further  Assurances.  Borrower agrees to execute and deliver,  and
cause each  Target  Center to execute  and  deliver,  to Lender,  promptly  upon
request  from  Lender,  such other and further  documents  as may be  reasonably
necessary or appropriate to consummate the transactions contemplated herein.

         8.12 Number and Gender. Whenever used herein, the singular number shall
include the plural and the plural the singular,  and the use of any gender shall
be applicable to all genders. The duties, covenants, obligations, and warranties
of Borrower in this Agreement shall be joint and several obligations of Borrower
and of each Borrower if more than one.

         8.13 Captions.  The captions,  headings,  and arrangements used in this
Agreement are for convenience only and do not in any way affect, limit, amplify,
or modify the terms and provisions hereof.

         8.14  Continuing  Agreement.  This is a  continuing  agreement  and all
rights,  powers,  and remedies of Lender under this Agreement and the other Loan
Documents  shall  continue  in full force and effect  until each Note is paid in
full as the same becomes due and payable and all other  Indebtedness is paid and
discharged, until Lender has no further obligation to advance moneys to Borrower
under this Agreement, and until Lender, upon request of Borrower, has executed a
written termination statement.  Furthermore,  the parties contemplate that there
may be times when no Indebtedness is owing, but notwithstanding such occurrence,
this Agreement (and all other Loan Documents) shall remain valid and shall be in
full force and effect as to subsequent Indebtedness and Advances,  provided that
Lender has not executed a written termination statement.

     8.15  Applicable  Law.  This  Agreement  and the  Loan  Documents  shall be
governed by and construed in accordance  with the laws of the State of Texas and
the laws of the United States applicable to transactions within such state.

     8.16 NO ORAL  AGREEMENTS.  THE WRITTEN LOAN AGREEMENT  REPRESENTS THE FINAL
AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS,  OR SUBSEQUENT  ORAL  AGREEMENTS  OF THE PARTIES.  THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.




                            [SIGNATURE PAGE FOLLOWS]


<PAGE>
                                SIGNATURE PAGE TO

                                 LOAN AGREEMENT

         EXECUTED as of the 31st day of January, 2000.

                           BORROWER:

                           PRIME REFRACTIVE, L.L.C.

                           By: /s/ Cheryl Williams
                           Name:  Cheryl Williams
                           Title: Chief Financial Officer

                           LENDER:

                           PRIME REFRACTIVE MANAGEMENT, L.L.C.

                           By: /s/ Cheryl Williams
                           Name:  Cheryl Williams
                           Title: Chief Financial Officer





                                 PROMISSORY NOTE

Austin, Texas                (LINE OF CREDIT)                   January 31, 2000



PROMISE TO PAY: For value  received,  the undersigned  Borrower  (whether one or
more) promises to pay to the order of Lender the Principal Amount, to the extent
advanced by Lender, together with interest on the unpaid balance of such amount,
in lawful  money of the United  States of America,  in  accordance  with all the
terms, conditions,  and covenants of this Note and the Loan Documents identified
below.

BORROWER:         Prime Refractive, L.L.C., a Delaware limited liability company

BORROWER'S ADDRESS FOR NOTICE:      1301 Capital of Texas Highway, Suite C-300
                                    Austin, Texas  78746
                                    Attention: President

LENDER:                             Prime Refractive Management, L.L.C.,
                                      a Delaware limited liability company

LENDER'S ADDRESS FOR PAYMENT:       1301 Capital of Texas Highway, Suite C-300,
                                    Austin, Texas 78746
                                    Attention: Chief Financial Officer

PRINCIPAL AMOUNT:                   Two Hundred Thousand Dollars ($200,000)

INTEREST RATE:                      Fifteen Percent (15%)

PAYMENT  TERMS:  Interest on the unpaid  balance of this Note is due and payable
quarterly,  beginning  November 1, 1999, and continuing  regularly and quarterly
thereafter on or before the first day of February,  May, August, until September
1, 2000 (the "Maturity  Date"),  when the outstanding  principal balance and all
accrued  interest shall be due and payable in full.  Interest will be calculated
on the unpaid  principal  balance.  Each payment  will be credited  first to the
accrued interest and then to the reduction of principal.

REVOLVING  LINE OF  CREDIT:  This Note  evidences  a  revolving  line of credit.
Subject to the terms of the Loan Agreement  between  Borrower and Lender of even
date  herewith,  all or any portion of the Principal  Amount of this Note may be
borrowed, paid, prepaid, repaid, and reborrowed,  from time to time prior to the
Maturity  Date and in accordance  with the Loan  Documents.  Each  borrowing and
repayment  hereunder will be (i) endorsed on an attachment to this Note, or (ii)
entered  in the books and  records of  Lender.  The books and  records of Lender
shall be prima facie  evidence  of all sums due  Lender.  If an event of default
exists  under  this Note or any Loan  Document,  then  Lender  shall be under no
obligation to make any advance under this Note.

LOAN AGREEMENT:  This Note is executed  pursuant to and is governed by the terms
of the Loan Agreement of even date herewith, executed by Borrower and Lender, as
amended (collectively, the "Loan Agreement").

1.       INTEREST PROVISIONS:

(a)      Rate:  The principal  balance of this Note from time to time  remaining
         unpaid prior to maturity  shall bear  interest at the Interest Rate per
         annum stated above.  Interest shall be calculated on the amount of each
         advance of the Principal Amount of this Note from the date of each such
         advance.

(b)      Maximum  Lawful  Interest:  The term  "Maximum  Lawful  Rate" means the
         maximum rate of interest and the term "Maximum Lawful Amount" means the
         maximum amount of interest that is permissible  under  applicable state
         or  federal  law for the type of loan  evidenced  by this  Note and the
         other Loan  Documents.  If the  Maximum  Lawful  Rate is  increased  by
         statute or other  governmental  action  subsequent  to the date of this
         Note, then the new Maximum Lawful Rate shall be applicable to this Note
         from  the  effective  date  thereof,  unless  otherwise  prohibited  by
         applicable law.

(c)  Spreading of Interest:  Because of the  possibility  of irregular  periodic
     balances of principal or premature  payment,  the total  interest that will
     accrue  under this Note cannot be  determined  in advance.  Lender does not
     intend to contract  for,  charge,  or receive more than the Maximum  Lawful
     Rate or Maximum Lawful Amount permitted by applicable state or federal law,
     and to  prevent  such an  occurrence  Lender  and  Borrower  agree that all
     amounts of  interest,  whenever  contracted  for,  charged,  or received by
     Lender,  with respect to the loan of money evidenced by this Note, shall be
     spread,  prorated,  or allocated  over the full period of time this Note is
     unpaid,  including  the period of any renewal or extension of this Note. If
     demand for payment of this Note is made by Lender  prior to the full stated
     term, the total amount of interest  contracted for, charged, or received to
     the time of such demand shall be spread,  prorated, or allocated along with
     any  interest  thereafter  accruing  over the full period of time that this
     Note  thereafter  remains  unpaid for the  purpose of  determining  if such
     interest exceeds the Maximum Lawful Amount.

(d)  Excess Interest:  At maturity  (whether by acceleration or otherwise) or on
     earlier final  payment of this Note,  Lender shall compute the total amount
     of interest that has been contracted for, charged, or received by Lender or
     payable by Borrower  under this Note and compare such amount to the Maximum
     Lawful Amount that could have been contracted for, charged,  or received by
     Lender. If such computation reflects that the total amount of interest that
     has been  contracted  for,  charged,  or  received  by Lender or payable by
     Borrower  exceeds the Maximum Lawful  Amount,  then Lender shall apply such
     excess to the reduction of the principal  balance and not to the payment of
     interest;  or if such excess interest exceeds the unpaid principal balance,
     such excess shall be refunded to Borrower.  This  provision  concerning the
     crediting or refund of excess  interest  shall control and take  precedence
     over all other  agreements  between  Borrower  and  Lender so that under no
     circumstances shall the total interest contracted for, charged, or received
     by Lender exceed the Maximum Lawful Amount.

(e)      Interest  After  Default:  At  Lender's  option,  the unpaid  principal
         balance shall bear interest after maturity  (whether by acceleration or
         otherwise) at the "Default  Interest  Rate." The Default  Interest Rate
         shall be, at Lender's  option,  (i) the Maximum  Lawful  Rate,  if such
         Maximum  Lawful  Rate is  established  by  applicable  law; or (ii) the
         Interest  Rate  stated  on the  first  page of this  Note plus five (5)
         percentage  points,  if  no  Maximum  Lawful  Rate  is  established  by
         applicable law; or (iii) eighteen percent (18%) per annum; or (iv) such
         lesser rate of interest as Lender in its sole  discretion may choose to
         charge;  but never more than the Maximum  Lawful Rate or at a rate that
         would cause the total interest  contracted for, charged, or received by
         Lender to exceed the Maximum Lawful Amount.

(f)      Daily  Computation of Interest:  To the extent  permitted by applicable
         law,  Lender at its option will calculate the per diem interest rate or
         amount  based on the actual  number of days in the year (365 or 366, as
         the case may be), and charge that per diem interest rate or amount each
         day. In no event  shall  Lender  compute the  interest in a manner that
         would cause Lender to contract for,  charge,  or receive  interest that
         would exceed the Maximum Lawful Rate or the Maximum Lawful Amount

2.       DEFAULT PROVISIONS:

(a)      EVENTS OF DEFAULT AND  ACCELERATION  OF  MATURITY:  LENDER  MAY,  AFTER
         THIRTY (30) DAYS' WRITTEN NOTICE TO BORROWER AND BORROWER'S  FAILURE TO
         CURE WITHIN SUCH 30-DAY  PERIOD AND WITHOUT  FURTHER  NOTICE OR DEMAND,
         (except as otherwise  required by statute),  ACCELERATE THE MATURITY OF
         THIS NOTE AND  DECLARE  THE ENTIRE  UNPAID  PRINCIPAL  BALANCE  AND ALL
         ACCRUED INTEREST AT ONCE DUE AND PAYABLE IF:

(i)  There is default in the payment of any installment of principal,  interest,
     or any other sum required to be paid under the terms of this Note or any of
     the Loan Documents; or

(ii) There  is a  breach  or  default  (other  than  by  Lender,  Prime  Medical
     Operating,  Inc. or Prime Medical Services, Inc.) under this Note or any of
     the Loan Documents,  including any instrument  securing the payment of this
     Note or any loan agreement relating to the advance of loan proceeds.

(b)      WAIVER BY BORROWER:  EXCEPT AS PROVIDED IN PARAGRAPH 2(a) HEREOF AND IN
         ANY OTHER LOAN DOCUMENT, BORROWER AND ALL OTHER PARTIES LIABLE FOR THIS
         NOTE  WAIVE,  DEMAND,  NOTICE  OF  INTENT TO  DEMAND,  PRESENTMENT  FOR
         PAYMENT,  NOTICE OF  NONPAYMENT,  PROTEST,  NOTICE OF  PROTEST,  GRACE,
         NOTICE OF DISHONOR,  NOTICE OF INTENT TO ACCELERATE MATURITY, NOTICE OF
         ACCELERATION  OF MATURITY,  AND  DILIGENCE IN  COLLECTION.  EACH MAKER,
         SURETY,  ENDORSER,  AND GUARANTOR OF THIS NOTE WAIVES AND AGREES TO ONE
         OR MORE  EXTENSIONS  FOR ANY PERIOD OR PERIODS OF TIME, AND ANY PARTIAL
         PAYMENTS, BEFORE OR AFTER MATURITY,  WITHOUT PREJUDICE TO THE HOLDER OF
         THIS NOTE. EACH MAKER, SURETY, ENDORSER, AND GUARANTOR WAIVES NOTICE OF
         ANY AND ALL RENEWALS, EXTENSIONS,  REARRANGEMENTS, AND MODIFICATIONS OF
         THIS NOTE.

(c)      Non-Waiver  by Lender:  Any previous  extension  of time,  forbearance,
         failure  to  pursue  some  remedy,  acceptance  of  late  payments,  or
         acceptance of partial payment by Lender, before or after maturity, does
         not constitute a waiver by Lender of its  subsequent  right to strictly
         enforce the collection of this Note according to its terms.

(d)  Other  Remedies  Not  Required:  Lender shall not be required to first file
     suit,  exhaust all remedies,  or enforce its rights against any security in
     order to enforce payment of this Note.

(e)      Joint and Several Liability: Each Borrower who signs this Note, and all
         of the other  parties  liable for the  payment  of this  Note,  such as
         guarantors,  endorsers,  and sureties, are jointly and severally liable
         for the payment of this Note.

(f)      Attorney's  Fees:  If Lender  requires  the  services of an attorney to
         enforce the payment of this Note or the  performance  of the other Loan
         Documents,  or if this Note is collected through any lawsuit,  probate,
         bankruptcy, or other judicial proceeding, Borrower agrees to pay Lender
         an amount equal to its reasonable  attorney's fees and other collection
         costs.  This  provision  shall be limited by any  applicable  statutory
         restrictions relating to the collection of attorney's fees.

3.       MISCELLANEOUS PROVISIONS:

(a)  Subsequent  Holder:  All references to Lender in this Note shall also refer
     to any  subsequent  owner or holder of this Note by  transfer,  assignment,
     endorsement, or otherwise.

(b)      Transfer:  Borrower  acknowledges  and agrees that Lender may  transfer
         this Note or partial  interests in the Note to one or more  transferees
         or participants, including without limitation transfers provided for in
         Section  8.10 of the Loan  Agreement.  Borrower  authorizes  Lender  to
         disseminate  to any  such  transferee  or  participant  or  prospective
         transferee or participant any information it has pertaining to the loan
         evidenced  by  this  Note,   including,   without  limitation,   credit
         information  on Borrower and any  guarantor of this Note and any of the
         type of information described in Section 8.10 of the Loan Agreement.

(c)      Other Parties Liable: All promises, waivers, agreements, and conditions
         applicable to Borrower shall likewise be applicable to and binding upon
         any other parties  primarily or  secondarily  liable for the payment of
         this Note, including all guarantors, endorsers, and sureties.

(d)      Successors  and Assigns:  The  provisions of this Note shall be binding
         upon and for the benefit of the successors,  assigns, heirs, executors,
         and administrators of Lender and Borrower.

(e)      No Duty or Special Relationship:  Borrower acknowledges that Lender has
         no duty of good faith to Borrower,  and Borrower  acknowledges  that no
         fiduciary,  trust, or other special  relationship exists between Lender
         and Borrower.

(f)      Modifications:  Any  modifications  agreed to by Lender relating to the
         release of  liability of any of the parties  primarily  or  secondarily
         liable for the  payment  of this  Note,  or  relating  to the  release,
         substitution,  or subordination of all or part of the security for this
         Note, shall in no way constitute a release of liability with respect to
         the other parties or security not covered by such modification.

(g)      Entire  Agreement:  Borrower  warrants  and  represents  that  the Loan
         Documents  constitute the entire agreement  between Borrower and Lender
         with  respect to the loan  evidenced  by this Note and  agrees  that no
         modification,  amendment,  or additional agreement with respect to such
         loan  or  the  advancement  of  funds  thereunder  will  be  valid  and
         enforceable unless made in writing signed by both Borrower and Lender.

(h)      Borrower's  Address  for  Notice:  All  notices  required to be sent by
         Lender to Borrower  shall be sent by U.S.  Mail,  postage  prepaid,  to
         Borrower's  Address  for Notice  stated on the first page of this Note,
         until Lender shall receive written  notification from Borrower of a new
         address for notice.

(i)      Lender's  Address for  Payment:  All sums payable by Borrower to Lender
         shall be paid at Lender's  Address for Payment stated on the first page
         of this Note, or at such other address as Lender shall  designate  from
         time to time.

(j)  Business Use:  Borrower warrants and represents to Lender that the proceeds
     of this Note will be used solely for business or commercial  purposes,  and
     in no way will the  proceeds be used for  personal,  family,  or  household
     purposes.

(k)      Chapter 15 Not  Applicable:  It is  understood  that  Chapter 15 of the
         Texas Credit Code  relating to certain  revolving  credit loan accounts
         and tri-party accounts is not applicable to this Note.

(l)      APPLICABLE  LAW: THIS NOTE HAS BEEN EXECUTED AND DELIVERED IN TEXAS AND
         SHALL BE CONSTRUED IN ACCORDANCE  WITH THE APPLICABLE LAWS OF THE STATE
         OF TEXAS AND THE LAWS OF THE  UNITED  STATES OF AMERICA  APPLICABLE  TO
         TRANSACTIONS IN TEXAS.

4.       LOAN DOCUMENTS:

(a)      This Note.

(b)      The Loan Agreement and the Loan Documents as defined therein.

(c)  All other  documents  signed in connection  with the Loan  Agreement or the
     loan evidenced by this Note,  including,  without limitation,  that certain
     Contribution  Agreement,  dated  effective  September 1, 1999,  between and
     among Borrower, Prime Medical Services, Inc., a Delaware corporation, Prime
     Medical Operating,  Inc., a Delaware  corporation,  Prime/BDR  Acquisition,
     L.L.C.,  a Delaware  limited  liability  company,  Prime/BDEC  Acquisition,
     L.L.C., a Delaware limited  liability  company,  Barnet Dulaney Eye Center,
     P.L.L.C.,   an  Arizona  professional  limited  liability  company,   LASIK
     Investors,  L.L.C., a Delaware limited liability company, David D. Dulaney,
     M.D.,  Ronald W.  Barnet,  M.D.,  and Mark  Rosenberg  (as  amended by that
     certain First Amendment to  Contribution  Agreement dated as of January 31,
     2000, among the foregoing parties,  the "Contribution  Agreement") and each
     Transaction   Document  (as  such  term  is  defined  in  the  Contribution
     Agreement).

                            [Signature page follows]


<PAGE>


                                       S-1



                                SIGNATURE PAGE TO

                                 PROMISSORY NOTE

EXECUTED as of the 31st day of January, 2000.

       BORROWER:

                  PRIME REFRACTIVE, L.L.C., a Delaware limited liability company


                   By: /s/ Teena E. Belcik

                   Printed Name:  Teena E. Belcik

                   Title: Treasurer







                        ASSIGNMENT AND SECURITY AGREEMENT

         THIS ASSIGNMENT AND SECURITY  AGREEMENT (this  "Agreement") is made and
entered  into  as of the  31st  day of  January,  2000,  by  and  between  Prime
Refractive  Management,  L.L.C.,  a  Delaware  limited  liability  company  (the
"Secured  Party") and LASIK  Investors,  L.L.C.,  a Delaware  limited  liability
company ("LASIK").

                                    RECITALS:

         A. LASIK and Secured  Party have  executed and  delivered  that certain
Contribution  Agreement  dated  effective  September 1, 1999,  between and among
LASIK,  Prime  Medical  Operating,   Inc,  a  Delaware  corporation,   Prime/BDR
Acquisition,  L.L.C.,  a  Delaware  limited  liability  company,  Prime  Medical
Services, Inc., a Delaware corporation ("PMSI"), Prime/BDEC Acquisition, L.L.C.,
a Delaware  limited  liability  company,  Prime  Refractive,  L.L.C., a Delaware
limited liability company (the "Debtor"),  Barnet Dulaney Eye Center,  P.L.L.C.,
an Arizona  professional  limited  liability  company,  David D. Dulaney,  M.D.,
Ronald W. Barnet,  M.D.,  and Mark  Rosenberg  (as amended by that certain First
Amendment to  Contribution  Agreement  dated as of January 31,  2000,  among the
foregoing parties, the "Contribution  Agreement"),  and Debtor and Secured Party
have executed and delivered that certain Loan Agreement, dated as of January 31,
2000 (the "Loan  Agreement"),  pursuant to which  Secured  Party  agrees to make
certain  loans to Debtor on the terms and  subject  to the  conditions  provided
therein.

         B. Secured Party has  requested  that LASIK pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or  hereafter  have  to  Secured  Party,  including,   without  limitation,  any
obligations arising under loans made pursuant to the Loan Agreement.

     C. LASIK desires to enter into this  Agreement as a material  inducement to
Secured Party's extension of credit under the Loan Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and  sufficiency  of which LASIK  acknowledges,  LASIK and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  LASIK hereby assigns,  transfers,  and
pledges to Secured  Party,  and LASIK hereby  grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

     (a) Interest in  Subsidiary.  All  ownership  interests of LASIK in Debtor,
whether now existing or hereafter  acquired and including,  without  limitation,
that certain 40% membership interest in Debtor;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
LASIK now or hereafter arising under any agreement  pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which LASIK is now or may  hereafter  become  entitled  to receive  with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following property (collectively, the "Additional Property") which LASIK becomes
entitled to receive or shall  receive as a result of its  ownership of any other
Collateral:  (i) any stock or other  ownership  certificate,  including  without
limitation,  any certificate representing a stock dividend or any certificate in
connection with any recapitalization,  reclassification,  merger, consolidation,
conversion,  sale of assets,  combination,  stock split, reverse stock split, or
spin-off;  (ii) any  option,  warrant,  subscription  or  right,  whether  as an
addition to or in substitution of any other  Collateral;  (iii) any dividends or
distributions  of any kind whatsoever,  whether  distributable in cash, stock or
other property;  (iv) any interest,  premium or principal payments;  and (v) any
conversion or redemption proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a),  (b) or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The security interest in the Collateral hereby granted by LASIK to Secured Party
may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any other  obligations)  under and pursuant to the Loan  Agreement  and each
promissory  note  (collectively,   the  "Note")  issued  pursuant  to  the  Loan
Agreement; and

                  (b) All liabilities and obligations of LASIK to Secured Party,
PMSI or any Prime Indemnified Parties (as defined in the Contribution Agreement)
under and pursuant to the Contribution Agreement or this Agreement.

     1.3  Subordination.  Liens created hereby are subordinate to liens in favor
of  Lenders  (as such term is  defined  in that  certain  Loan  Agreement  for a
$14,000,000 advancing term loan, entered into by Secured Party, Bank of America,
N.A., as administrative agent, BankBoston, N.A., as documentation agent and such
Lenders).
                                   ARTICLE II

        LASIK'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

         LASIK hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral. LASIK has good and marketable title to the
Collateral  free  and  clear  of any  liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2 Power & Authority. LASIK has the lawful right, power, and authority
to grant the Security Interest in the Collateral. This Agreement,  together with
all filings and other actions necessary or desirable to perfect and protect such
security  interest,  which have been duly  taken,  create a valid and  perfected
first  priority  security  interest in the  Collateral  securing the payment and
performance of the Obligations.

         2.3 No  Agreements.  The  Interests  are not  subject  to any  right of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which LASIK or the issuer  thereof is
bound.  Except as expressly provided otherwise in the Contribution  Agreement or
any  Transaction  Document (as therein  defined),  no restrictions or conditions
exist  with  respect  to the  transfer  or voting of any  securities  pledged as
Collateral.

                                   ARTICLE III

                  LASIK'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1  Solvency of LASIK.  As of the date  hereof,  (i) LASIK is solvent;
(ii) the fair saleable  value of LASIK's assets  exceeds its  liabilities  (both
fixed and  contingent);  (iii)  LASIK has  sufficient  capital to satisfy all of
LASIK's obligations as they become due; (iv) no receiver,  trustee, or custodian
has been appointed for, or taken possession of, all or substantially  all of the
assets of LASIK,  either in a  proceeding  brought  by LASIK or in a  proceeding
brought  against  LASIK;  (v) LASIK is not the subject of a petition  for relief
under  the  United  States  Bankruptcy  Code or any  similar  federal  or  state
insolvency  law,  including  without  limitation a petition  filed by LASIK or a
petition filed by a third party seeking relief against LASIK; and (vi) LASIK has
no intention of filing a petition for relief under the United States  Bankruptcy
Code or any  similar  federal or state  insolvency  law, or of seeking any other
form of creditor relief.

         3.2  Authority  and  Compliance.  LASIK has full power and authority to
enter into this Agreement.  LASIK has full power and authority to enter into and
perform  its  obligations  under each  Other  Agreement.  No further  consent or
approval is required as a condition  to the  validity of this  Agreement  or any
Other Agreement.  LASIK is in compliance with all applicable  laws,  ordinances,
statutes, orders, regulations,  judgments, writs, or decrees of any governmental
entity to which it is subject.

         3.3  Binding  Agreement.   This  Agreement  and  each  Other  Agreement
constitute  valid and legally  binding  obligations of LASIK, in accordance with
their terms, subject to the applicable bankruptcy,  insolvency,  reorganization,
moratorium, and similar laws affecting creditors' rights generally.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of LASIK, threatened before any court or administrative agency which will or may
have a  material  adverse  effect on the  financial  condition  of LASIK or upon
LASIK's  ability to perform its  obligations  under this  Agreement or any Other
Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on LASIK or affecting  its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement or any Other Agreement.

         3.6  Ownership  of  Assets.  LASIK  has  good  and  full  title  to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. LASIK has filed all tax returns required to be filed by LASIK.

                                   ARTICLE IV

                  LASIK'S COVENANTS WITH RESPECT TO COLLATERAL

         LASIK  covenants  and  agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   LASIK   covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with  LASIK's  endorsement  thereon  and/or  accompanied  by proper
instruments of transfer and assignment duly executed in blank.

         4.2 Further Assurances. LASIK will contemporaneously with the execution
hereof and from time to time  thereafter  at its  expense  promptly  execute and
deliver all  further  instruments  and  documents  and take all  further  action
necessary  or  appropriate  or that  Secured  Party may  request in order (i) to
perfect and protect the  security  interest  created or  purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received  by LASIK shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is received by LASIK, together with such instruments of transfer as Secured
Party may request,  shall  immediately be delivered to or deposited with Secured
Party and held by Secured Party as Collateral under the terms of this Agreement.
If the  Additional  Property  received by LASIK and  delivered to Secured  Party
pursuant  to this  Section  shall be shares of stock or other  securities,  such
shares  of  stock  or  other  securities  shall  be duly  endorsed  in  blank or
accompanied by proper  instruments  of transfer and assignment  duly executed in
blank with, if requested by Secured Party,  signatures guaranteed by a member or
member organization in good standing of an authorized Securities Transfer Agents
Medallion  Program,  all in form and substance  satisfactory  to Secured  Party.
Secured Party shall be deemed to have possession of any Collateral in transit to
Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  LASIK  will  not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens.  Neither LASIK nor any person acting on LASIK's  behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
LASIK will promptly  notify  Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7 Agreements Pertaining to Collateral. LASIK will not transfer any voting
rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
LASIK  will not  consent to or approve  of the  issuance  of (i) any  additional
interests  or  shares  of any  class  of  securities  of such  issuer,  (ii) any
instrument  convertible  voluntarily by the holder thereof or automatically upon
the occurrence or non-occurrence of any event or condition into, or exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.

         4.9 Restrictions on Securities. LASIK will not enter into any agreement
creating,  or otherwise  permit to exist,  any restriction or condition upon the
transfer,  voting or control of any securities pledged as Collateral,  except as
consented  to in writing  by  Secured  Party.  As to any  securities  pledged as
collateral,  LASIK will not  consent to or approve of any stock  split,  reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding the Interests  unless  consented to in writing by Secured
Party.

                                    ARTICLE V

                          LASIK'S AFFIRMATIVE COVENANTS

         Until payment and performance of all  Obligations,  LASIK covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  LASIK  and of any  condition,  event or act  which  comes to its
attention  that  would  or might  have a  material  adverse  effect  on  LASIK's
financial condition.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all  Obligations,  LASIK covenants and
agrees that LASIK will not,  without the prior written  consent of Secured Party
grant, suffer, or permit liens on, or security interests in, the Collateral.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid  under  the Loan  Agreement  or any Note  (including,  without  limitation,
principal, interest and fees due thereunder) within ten (10) calendar days after
such amount is due;

                  (b) The failure of LASIK to pay any  Obligation  described  in
Section  1.2(b)  within ten (10) calendar days after such amount is due (and, if
applicable  under the terms of any contractual  agreement  creating or governing
such Obligation, after the expiration of any cure period expressly required);

                  (c)      LASIK's breach of a covenant in this Agreement;

     (d) Any representation or warranty made by LASIK in this Agreement shall be
false or materially  misleading,  as determined in the reasonable  discretion of
Secured Party;

                  (e) Any event of default  shall  occur  under the terms of the
Loan  Agreement  and shall not be cured within the time  expressly  provided for
with respect thereto in the Loan Agreement;

                  (f) If LASIK or Debtor,  or any other party  obligated  to pay
any portion of the Obligations:  (i) becomes  insolvent,  or makes a transfer in
fraud of  creditors,  or makes an assignment  for the benefit of  creditors,  or
admits in  writing  its  inability  to pay its debts as they  become  due;  (ii)
generally is not paying its debts as such debts become due and Secured Party, in
good faith,  determines  that such event or  condition  could lead to a material
impairment  of the  Collateral,  or any part  thereof,  or of any other  payment
security for any of the Obligations;  (iii) has a receiver, trustee or custodian
appointed for, or take possession of, all or substantially  all of the assets of
such  party or any of the  Collateral,  either in a  proceeding  brought by such
party or in a proceeding  brought against such party and such appointment is not
discharged or such possession is not terminated within sixty (60) days after the
effective  date  thereof  or  such  party  consents  to or  acquiesces  in  such
appointment  or  possession;  (iv) files a petition  for relief under the United
States  Bankruptcy  Code  or any  other  present  or  future  federal  or  state
insolvency,  bankruptcy  or  similar  laws  (all  of the  foregoing  hereinafter
collectively called "Applicable  Bankruptcy Law") or an involuntary petition for
relief is filed against such party under any Applicable  Bankruptcy Law and such
involuntary  petition is not  dismissed  within sixty (60) days after the filing
thereof,  or an order  for  relief  naming  such  party  is  entered  under  any
Applicable  Bankruptcy  Law,  or  any  composition,   rearrangement,  extension,
reorganization or other relief of debtors now or hereafter existing is requested
or consented to by such party;  (v) fails to have discharged  within a period of
sixty (60) days any  attachment,  sequestration  or similar writ levied upon, or
any claim against or affecting, any property of such party; or (vi) fails to pay
within ninety (90) days any final money judgment against such party; or

                  (g) The issuer of any securities constituting Collateral files
a petition  for relief  under any  Applicable  Bankruptcy  Law,  an  involuntary
petition  for  relief is filed  against  any such  issuer  under any  Applicable
Bankruptcy Law and such involuntary petition is not dismissed within thirty (30)
days after the filing thereof,  or an order for relief naming any such issuer is
entered under any Applicable Bankruptcy Law.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of LASIK,  either in Secured  Party's  own right or in the name of LASIK
and in the same manner and to the same extent that LASIK might reasonably so act
if this Agreement had not been made: (i) do all things requisite, convenient, or
necessary to enforce the performance and observance of all rights,  remedies and
privileges of LASIK arising from the Collateral, or any part thereof,  including
without limitation compromising,  waiving,  excusing, or in any manner releasing
or discharging  any  obligation of any party to or arising from the  Collateral;
(ii) take possession of the books,  papers,  chattel paper,  documents of title,
and accounts of LASIK, wherever located,  relating to the Collateral;  (iii) sue
or otherwise collect and receive money attributable to the Collateral;  and (iv)
exercise  any other  lawfully  available  powers or  remedies,  and do all other
things which Secured Party deems requisite, convenient or necessary or which the
Secured Party deems proper to protect the Security Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by  applicable  law (LASIK hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name  or as  LASIK's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in  equity,  against  LASIK and all
persons and  corporations  lawfully  claiming by or through or under LASIK.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in any type of offering  which  complies  with, or is exempt from the
registration requirements of, the Securities Act of 1933, and no sale so made in
good faith by Secured Party shall be deemed to be not "commercially  reasonable"
because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance  with the terms hereof or under the  Contribution  Agreement,  the
Loan Agreement or any Note; (d) then, to or among the amounts of fees,  interest
and  principal  then owing and unpaid in  respect  of the  Obligations,  in such
priority as Secured Party may determine in its discretion; and (e) the remainder
of such  proceeds,  if any,  shall be paid to LASIK.  If such proceeds  shall be
insufficient to discharge the entire  Obligations,  Secured Party shall have any
other available  legal recourse  against LASIK under, or for the performance of,
the Contribution Agreement, the Loan Agreement and any Note, for the deficiency,
together with interest  thereon at the maximum rate permitted  under  applicable
law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies of LASIK, in respect to any of the Collateral or agreements  pertaining
thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  LASIK hereby  appoints
Secured Party as attorney-in-fact of LASIK, with full authority in the place and
stead of LASIK and in the name of LASIK,  Secured Party or otherwise,  from time
to time on Secured  Party's  discretion  and upon the  occurrence of an Event of
Default,  to take any action and to execute any  instrument  which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by  Secured  Party.  If LASIK  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection therewith shall be payable by LASIK under Section 8.8. In
no event, however,  shall Secured Party have any obligation or duties whatsoever
to perform any  covenant or agreement of LASIK  contained  herein,  and any such
performance by Secured Party shall be wholly discretionary with Secured Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights pertaining to any Collateral.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations, responsibilities, or duties of LASIK arising in connection with the
Collateral assigned hereunder or otherwise bind Secured Party to the performance
of any obligations respecting the Collateral, it being expressly understood that
Secured  Party shall not be obligated  to perform,  observe,  or  discharge  any
obligation, responsibility, duty, or liability of LASIK in respect of any of the
Collateral,  including without limitation  appearing in or defending any action,
expending  any money or incurring any expense in  connection  therewith.  TO THE
FULLEST  EXTENT  PERMITTED  BY  APPLICABLE  LAW,  LASIK  SHALL AND DOES AGREE TO
INDEMNIFY, PROTECT, DEFEND AND HOLD HARMLESS SECURED PARTY AND ITS SUBSIDIARIES,
AND EACH OF  THEIR  OFFICERS,  DIRECTORS,  REPRESENTATIVES,  AGENTS,  EMPLOYEES,
LENDERS,  SUCCESSORS  AND  ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,
DAMAGES,  LOSSES,  FINES,  PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND
EXPENSES  (INCLUDING COURT COSTS,  ATTORNEY'S FEES AND COST OF INVESTIGATION) OF
ANY NATURE, KIND OR DESCRIPTION OF ANY PERSON OR ENTITY, DIRECTLY OR INDIRECTLY,
ARISING OUT OF,  CAUSED BY OR RESULTING  FROM (IN WHOLE OR IN PART),  ANY ACT OR
OMISSION  OF SECURED  PARTY,  OR ANYONE  ACTING ON BEHALF OF SECURED  PARTY,  IN
CONNECTION  WITH  THE  COLLATERAL,   INCLUDING  WITHOUT  LIMITATION  ANY  MARKET
FLUCTUATIONS  IN THE  COLLATERAL  AS A RESULT  OF  SECURED  PARTY'S  SALE OF, OR
FAILURE TO SELL, THE INTERESTS AT ANY  PARTICULAR  TIME WHEN IT HAS THE RIGHT TO
DO  SO.  THE  FOREGOING  INDEMNITY  SHALL  SURVIVE  THE  EXPIRATION  OR  EARLIER
TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  LASIK,  appear  in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of Secured Party to Prevent or Remedy Default. If LASIK shall
fail to perform any of the covenants,  conditions and agreements  required to be
performed and observed by LASIK under any Other Agreement,  or in respect of the
Collateral  (subject to any applicable  default cure period),  Secured Party (a)
may but shall not be obligated to take any action Secured Party deems  necessary
or  desirable  to prevent or remedy any such  default by LASIK or  otherwise  to
protect the Security  Interest,  and (b) shall have the  absolute and  immediate
right to take  possession  of the  Collateral or any part thereof (to the extent
Secured Party has not previously  taken  possession) to such extent and as often
as the Secured Party,  in its sole  discretion,  deems necessary or desirable in
order to prevent or to cure any such  default by LASIK,  or otherwise to protect
the security of this Agreement. Secured Party may advance or expend such sums of
money for the  account of LASIK as Secured  Party in its sole  discretion  deems
necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure proceedings commenced and subsequently abandoned.

         8.9.  Remedies.  No right or remedy herein reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.10 LASIK's  Waivers.  LASIK waives notice of the  creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.11 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the  Obligations.  LASIK waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
LASIK agrees that  Secured  Party shall have no duty or  obligation  to LASIK to
apply to the Obligations any such other security or proceeds thereof.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to LASIK their  respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  LASIK:          LASIK Investors, L.L.C.
                                  4800 North 22nd Street
                                  Phoenix, Arizona  85016

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations,  warranties, and agreements of LASIK if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of LASIK.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by LASIK shall be binding upon Secured Party unless in writing,  and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by LASIK  shall  operate  as a waiver of any  other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions  between Secured Party and LASIK shall be closed at any time, shall
be equally applicable to any new transactions thereafter.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  LASIK  acknowledges  that Secured  Party intends to make a
collateral  assignment of its rights under this Agreement for the benefit of one
or more of its lenders. LASIK may not assign this Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

         9.10 ENTIRE AGREEMENT. THIS AGREEMENT, THE LOAN AGREEMENT, THE NOTE AND
THE  CONTRIBUTION  AGREEMENT  (AND THE OTHER  AGREEMENTS  CONTEMPLATED  THEREIN)
REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY
EVIDENCE  OF  PRIOR,  CONTEMPORANEOUS,  OR  SUBSEQUENT  ORAL  AGREEMENTS  OF THE
PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED as of this 31st day of January, 2000.

DEBTOR:                          LASIK Investors, L.L.C.


                                   By:  /s/ Ronald W. Barnet, M.D.
                                        Ronald W. Barnet, M.D., manager


                                   By:  /s/ David D. Dulaney, M.D.
                                        David D. Dulaney, M.D., manager



SECURED PARTY:                   Prime Refractive Management, L.L.C.

                                   By:/s/ Cheryl Williams

                                   Name: Cheryl Williams

                                   Title: Chief Financial Officer






                       LIMITED LIABILITY COMPANY AGREEMENT

                           OF PRIME REFRACTIVE, L.L.C.

     Organized under the Delaware Limited Liability Company Act (the "Act").

                                   ARTICLE I.

                                NAME AND LOCATION

     Section  1.1.  Name.  The name of this limited  liability  company is Prime
Refractive, L.L.C. (the "Company").

         Section  1.2.  Members.  The  only  members  of the  Company  upon  the
execution of this Limited Liability Company Agreement (this  "Agreement")  shall
be Prime Refractive  Management,  L.L.C., a Delaware limited  liability  company
("Prime  Management"),  and LASIK Investors L.L.C., a Delaware limited liability
company ("LASIK").  LASIK acknowledges and agrees that it initially owned all of
the outstanding  membership  interests of the Company and that Prime  Management
acquired its membership interest in the Company from LASIK. For purposes of this
Agreement,  the  "Members"  shall include such named members and any new members
admitted  pursuant  to the terms of this  Agreement,  but does not  include  any
person or entity who has ceased to be a member in the Company.

     Section 1.3. Principal Office. The principal office of the Company shall be
located in 1301 Capital of Texas Hwy., Suite C-300, Austin, Texas 78746-6550, or
such other location as may be selected by the Members.

     Section 1.4. Registered Agent and Address. The name of the registered agent
and the  address  of the  registered  office of the  Company as set forth in the
Certificate of Formation of the Company are:

                          The Corporation Trust Company
                          1209 Orange Street
                          Wilmington, Delaware 19801

     Section 1.5.  Other  Offices.  Other offices and other  facilities  for the
transaction of business shall be located at such places as the Managers may from
time to time determine.

         Section 1.6  Contribution  Agreement.  The Company was initially formed
with a single member, LASIK, in connection with the transactions contemplated by
that certain  Contribution  Agreement dated effective  September 1, 1999, by and
among Prime Medical  Operating,  Inc., a Delaware  corporation  ("PMOI"),  Prime
Medical Services,  Inc., a Delaware corporation ("PMSI"),  LASIK, Barnet Dulaney
Eye Center,  P.L.L.C.,  an Arizona  professional  limited liability company, the
Company, Prime Management,  Prime/BDEC  Acquisition,  L.L.C., a Delaware limited
liability company,  Prime/BDR Acquisition,  L.L.C., a Delaware limited liability
company,  David D. Dulaney, M.D., Ronald W. Barnet, M.D., and Mark Rosenberg (as
amended by that certain First  Amendment to  Contribution  Agreement dated as of
January 31, 2000, among the foregoing  parties,  the "Contribution  Agreement").
This agreement  supercedes and replaces any prior membership  agreement or other
governing or organizational document of the Company.

                                   ARTICLE II.

                                   MEMBERSHIP

     Section 2.1. Members' Interests.  The "Membership  Interest" of each Member
is set forth on Exhibit A.

     Section 2.2. Admission to Membership. The admission of new Members shall be
only by the unanimous  vote of the Members.  If new members are  admitted,  this
Agreement shall be amended to reflect each Member's revised Membership Interest.

     Section 2.3.  Property  Rights.  No Member shall have any right,  title, or
interest in any of the property or assets of the Company.

     Section  2.4.  Liability  of  Members.  No Member of the  Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment decree, or order of court.

         Section 2.5.  Transferability of Membership.  Except as provided below,
Membership  Interests in the Company are  transferable  only with the  unanimous
written  consent  of all  Members.  If such  unanimous  written  consent  is not
obtained when  required,  the  transferee  shall be entitled to receive only the
share of  profits  or other  compensation  by way of  income  and the  return of
contributions  to which  the  transferor  Member  otherwise  would be  entitled.
Notwithstanding the foregoing,  (i) the Membership Interests of Prime Management
may be freely transferred,  without consent, to any entity that is then owned or
controlled, directly or indirectly, by PMSI (or its successor in interest), (ii)
the  Membership  Interests  of any  Member  may be freely  assigned,  pledged or
otherwise  transferred,  without  consent,  to  secure  any debt,  liability  or
obligation owed to PMOI or its  subsidiaries  or affiliates by the Company,  any
Member or any entity affiliated with the Company, (iii) the Membership Interests
of any Member may be freely assigned, pledged or otherwise transferred,  without
consent, in favor of the Lender(s) under, or by the Lender(s) as a result of the
enforcement of any security  interest  arising  pursuant to, that certain Senior
Credit  Facility of PMSI (as  amended) or pursuant to that  certain  $14,000,000
Credit Facility of Prime Management (as amended),  (iv) the Membership Interests
of any Member may be freely  transferred,  without  consent,  pursuant to and in
accordance with the express terms and conditions of the Contribution  Agreement,
and (iv) the  pledge  by LASIK  (pursuant  to  Section  6.3 of the  Contribution
Agreement) of its right to receive  distributions from the Company in respect of
its  Membership  Interest  shall not be deemed to violate any  provision of this
Agreement..

         Section 2.6. Resignation of Members. A Member may not withdraw from the
Company except on the unanimous consent of the remaining  Members.  The terms of
the Members  withdrawal  shall be determined by agreement  between the remaining
Members and the withdrawing Member.

                                  ARTICLE III.

                                MEMBERS' MEETINGS

         Section  3.1.  Time and Place of Meeting.  All  meetings of the Members
shall be held at such  time and at such  place  within or  without  the State of
Delaware as shall be determined by the Managers.

         Section 3.2. Annual  Meetings.  In the absence of an earlier meeting at
such  time and place as the  Managers  shall  specify,  annual  meetings  of the
Members shall be held at the  principal  office of the Company on the date which
is thirty  (30) days after the end of the  Company's  fiscal year if not a legal
holiday,  and if a legal holiday,  then on the next full business day following,
at 10:00 a.m.,  at which  meeting the Members may transact  such business as may
properly be brought before the meeting.

     Section  3.3.  Special  Meetings.  Special  meetings  of the Members may be
called at any time by any Member.  Business transacted at special meetings shall
be confined to the purposes stated in the notice of the meeting.

         Section 3.4.  Notice.  Written or printed notice stating the place, day
and hour of any Members'  meeting,  and, in the case of a special  meeting,  the
purpose or purposes for which the meeting is called, shall be delivered not less
than ten (10) days nor more than thirty (30) days before the date of the special
meeting,  either  personally  or by mail,  by or at the  direction of the person
calling the meeting, to each Member entitled to vote at such meeting. If mailed,
such notice shall be deemed to be delivered three (3) days after it is deposited
in the United States mail,  postage prepaid,  to the Member at his address as it
appears on the records of the Company at the time of mailing.

         Section 3.5. Quorum. Members present in person or represented by proxy,
holding  more than fifty  percent  (50%) of the total votes which may be cast at
any meeting  shall  constitute  a quorum at all  meetings of the Members for the
transaction  of  business.  If,  however,  such  quorum  shall not be present or
represented at any meeting of the Members, the Members entitled to vote, present
in person or represented by proxy,  shall have power to adjourn the meeting from
time to time,  without notice other than  announcement  at the meeting,  until a
quorum shall be present or represented. When any adjourned meeting is reconvened
and a quorum shall be present or  represented,  any  business may be  transacted
which might have been  transacted at the meeting as originally  noticed.  Once a
quorum is constituted,  the Members present or represented by proxy at a meeting
may  continue  to  transact  business  until  adjournment,  notwithstanding  the
subsequent  withdrawal therefrom of such number of Members as to leave less than
a quorum.

         Section 3.6. Voting. When a quorum is present at any meeting,  the vote
of the Members, whether present or represented by proxy at such meeting, holding
more  than  fifty  percent  (50%) of the  total  votes  which may be cast at any
meeting shall be the act of the Members,  unless the vote of a different  number
is required by the Act, the  Certificate of Formation or this Limited  Liability
Company Agreement. Each Member shall be entitled to one vote for each percentage
point  represented by their  Membership  Interest.  Fractional  percentage point
interests shall be entitled to a corresponding fractional vote.

         Section  3.7.  Proxy.  Every  proxy must be  executed in writing by the
Member or by his duly authorized  attorney-in-fact,  and shall be filed with the
Secretary of the Company prior to or at the time of the meeting.  No proxy shall
be  valid  after  eleven  (11)  months  from the  date of its  execution  unless
otherwise  provided  therein.  Each proxy shall be  revocable  unless  expressly
provided therein to be irrevocable and unless otherwise made irrevocable by law.

         Section  3.8.  Action  by  Written  Consent.  Any  action  required  or
permitted  to be taken at any  meeting  of the  Members  may be taken  without a
meeting if a consent in  writing,  setting  forth the action so taken,  shall be
signed by all of the Members entitled to vote with respect to the subject matter
thereof,  and such  consent  shall have the same force and effect as a unanimous
vote of Members.

         Section 3.9. Meetings by Conference Telephone.  Members may participate
in and hold  meetings  of Members by means of  conference  telephone  or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

                                   ARTICLE IV.

                        MEMBERSHIP CAPITAL CONTRIBUTIONS

         Except  for  each  Member's  initial  capital   contribution   made  in
connection with the formation of the Company, no capital  contributions shall be
required  of any  Member  without  the  approval  of all the  Members  to  raise
additional capital, and only then proportionately as to each Member.

                                   ARTICLE V.

                             DISTRIBUTION TO MEMBERS

         The Company shall not  distribute (or allow to be  distributed)  to its
members,  with respect to their  respective  membership  interests,  any cash or
other  property  of the  Company  or its  subsidiaries  if,  at the  time of the
proposed   distribution,   any  amounts  (whether  principal  or  interest)  are
outstanding  under the Credit  Documents or the Target Center Lending  Documents
(as such terms are  defined in the  Contribution  Agreement).  Furthermore,  the
Company  shall  pay  all  available  cash  flow  in  payment  of  the  Company's
outstanding obligations,  if any, under the Working Capital Line and Development
Facility (as such terms are defined in the Contribution Agreement), irrespective
of whether such payments exceed the minimum required  payments under the Working
Capital Line and Development Facility.  For purposes of allocating such payments
among any two or more of such  outstanding  obligations,  such payments shall be
allocated  pro rata,  based upon the  respective  balances of such  obligations,
unless (i) a greater  portion of the  payment is  required  to be paid  toward a
given  obligation in order to prevent a default with respect to that  obligation
(but only to the extent  necessary  to prevent  such a default)  or (ii)  eighty
percent (80%) of the managers of the Company elect to allocate the payments in a
different manner.

         Notwithstanding  the foregoing,  as long as no party other than PMSI or
PMOI is in default  under the  Contribution  Agreement or any other  Transaction
Document (as defined in the Contribution Agreement, but excluding,  however, the
Credit Documents and the Target Center Lending  Documents),  then, to the extent
that (but only to the extent that) the Company possesses the cash flow necessary
(in  the  reasonable  discretion  of a  majority  of its  managers)  to pay  its
liabilities in the ordinary course  consistent with past practices,  the Company
agrees to make  quarterly  estimates  of its taxable  income for the current tax
year  and,  if not  prohibited  by law,  distribute  quarterly  (the  "Quarterly
Distributions")  an amount that would cover the federal and state  income  taxes
required to be paid by its members with respect  such taxable  income,  based on
each member's then current proportionate interest in the Company,  assuming that
all members pay income taxes on the Company's  taxable  earnings at a rate equal
to the highest  effective  individual  tax rate in effect from time to time (the
"Assumed Tax Rate");  provided,  further,  that the Company shall  determine its
actual  taxable  income at the end of each taxable year and (A) if the Quarterly
Distributions  in a given year should  have been  higher  based on the amount of
actual taxable income for that year,  promptly  distribute the amounts necessary
to eliminate such  deficiency or (B) if the Quarterly  Distributions  in a given
year  should have been lower  based on the amount of actual  taxable  income for
that  year,  withhold  dollar  for  dollar  from the first  following  Quarterly
Distribution,  and then against  subsequent  Quarterly  Distributions  in a like
manner, the amounts necessary to eliminate such surplus.

         Subject to the foregoing,  the Managers shall determine,  in their sole
discretion,  the  amount  and  timing  of all  distributions  from the  Company.
Distributions  shall be  divided  among the  Members  in  accordance  with their
Membership Interests. Distributions in kind shall be made on the basis of agreed
value  as  determined  by the  Members.  In no  event  may  the  Company  make a
distribution  to  its  Members  if,  immediately  after  giving  effect  to  the
distribution,  all  liabilities  of the Company,  other than  liabilities to the
Members with respect to their  interests and  liabilities for which the recourse
of creditors is limited to  specified  property of the Company,  exceed the fair
value of the  Company's  assets;  except that the fair value of property that is
subject to  liability  for which  recourse of  creditors  is  limited,  shall be
included  in the  Company  assets  only to the extent that the fair value of the
property  exceeds that  liability.  Except as contemplated in this Article V, no
distributions  of cash or  other  assets  of the  Company  shall  be made to the
Members in their capacity as owners of the Company.

                                   ARTICLE VI.

              ALLOCATION OF NET PROFITS AND LOSSES FOR TAX PURPOSES

         For  accounting  and income tax  purposes,  all items of income,  gain,
loss,  deduction,  and  credit of the  Company  for any  taxable  year  shall be
allocated  among the  Members in  accordance  with their  respective  Membership
Interests,  except as may be otherwise  required by the Internal Revenue Code of
1986, as amended.

                                  ARTICLE VII.

                           DISSOLUTION AND WINDING UP

     Section 7.1.  Dissolution.  Notwithstanding  any  provision of the Act, the
Company shall be dissolved only upon the first of the following to occur:

               (a) Forty (40) years from the date of filing the  Certificate  of
          Formation of the Company;

               (b)  Written   consent  of  all  the  then  current   Members  to
          dissolution;

                  (c) The  bankruptcy of a Member,  unless there is at least one
         remaining Member and such Member or, if more than one remaining Member,
         all remaining Members agree to continue the Company and its business.

         Section 7.2.  Winding Up.  Unless the Company is continued  pursuant to
Section 7.1(c) of this Article VII., in the event of dissolution of the Company,
the Managers (excluding any Manager(s) holding office pursuant to designation by
a Member subject to bankruptcy  proceedings) shall wind up the Company's affairs
as soon  as  reasonably  practicable.  On the  winding  up of the  Company,  the
Managers  shall pay and/or  transfer the assets of the Company in the  following
order:

               (a) In discharging liabilities (including loans from Members) and
          the expenses of concluding the Company's affairs; and

               (b) The balance,  if any, shall be divided between the Members in
          accordance with the Members' Membership Interests.

                                  ARTICLE VIII.

                                    MANAGERS

         Section 8.1. Selection of Managers.  Management of the Company shall be
vested in the  Managers.  Initially,  the Company  shall have five (5) Managers,
being Ken  Shifrin,  Teena  Belcik,  and Brad  Hummel,  (as the initial  Manager
designees of Prime  Management),  David D. Dulaney,  M.D., and Ronald W. Barnet,
M.D. (as the initial  Manager  designees of LASIK).  Thereafter,  for so long as
there are five (5) Managers, (a) Prime Management shall be entitled to designate
three (3) of the  Managers;  and (b) LASIK shall be entitled  to  designate  the
remaining two (2) of the Managers. Notwithstanding the foregoing, a Member shall
not be entitled to designate any Manager unless its Membership Interest: (x) has
not  (other  than  as  allowed  under  Section  2.5  of  this   Agreement)  been
transferred,   repurchased,  assigned,  pledged,  hypothecated  or  in  any  way
alienated;  and (y)  equals or  exceeds  forty  percent  (40%) of the  aggregate
Membership  Interests;  provided,  however,  that if the  immediately  preceding
subsection  (y) shall apply to LASIK  solely  because of an exercise by LASIK of
its put rights  under  Section  9.8 of the  Contribution  Agreement,  then LASIK
shall,  unless  and  until  there is an  additional  decrease  in it  Membership
Interest other than pursuant to Section 9.8 of the  Contribution  Agreement,  be
entitled to designate only one Manager in the manner provided above. The Members
may, by unanimous vote of all Members,  from time to time,  change the number of
Managers of the Company and remove or add Managers accordingly.  A Manager shall
serve as a Manager until their resignation or removal pursuant to Section 8.2 or
8.3 of this  Article  VIII.  Managers  need  not be  residents  of the  State of
Delaware or Members of the Company.

         Section 8.2. Resignations.  Each Manager shall have the right to resign
at any time upon  written  notice of such  resignation  to the  Members.  Unless
otherwise  specified in such written notice,  the resignation  shall take effect
upon the  receipt  thereof,  and  acceptance  of such  resignation  shall not be
necessary to make same effective.  The Member who designated a resigning manager
shall be entitled to designate  the  successor  thereto and all Members agree to
take such action as may be necessary to cause the election of all such successor
Managers.

         Section 8.3.  Removal of Managers.  Any Manager may be removed,  for or
without cause,  at any time, but only by the Member who designated such Manager,
upon the written notice to all Members.  The Member who designated  such removed
Manager  shall be entitled to designate  the  successor  thereto and all Members
agree to take such action as may be  necessary to cause the election of all such
successor Managers.

         Section  8.4.  General  Powers.  The  business of the Company  shall be
managed by its Managers, which may, by the vote or written consent in accordance
with this  Agreement,  exercise any and all powers of the Company and do any and
all such  lawful  acts and  things  as are not by the Act,  the  Certificate  of
Formation or this Limited Liability Company Agreement directed or required to be
exercised or done by the Members, including, but not limited to, contracting for
or incurring on behalf of the Company debts,  liabilities and other obligations,
without the consent of any other person, except as otherwise provided herein.

     Section 8.5. Place of Meetings.  The Managers of the Company may hold their
meetings,  both  regular  and  special,  either  within or without  the State of
Delaware.

         Section 8.6. Annual Meetings.  The annual meeting of the Managers shall
be held without further notice  immediately  following the annual meeting of the
Members, and at the same place, unless by unanimous consent of the Managers that
such time or place shall be changed.

     Section 8.7. Regular Meetings. Regular meetings of the Managers may be held
without  notice at such time and place as shall from time to time be  determined
by the Managers.

     Section  8.8.  Special  Meetings.  Special  meetings  of the Mangers may be
called by any Manager on seven (7) days notice to each Manager, with such notice
to be given personally, by mail or by telecopy, telegraph or mailgram.

         Section  8.9.  Quorum and Voting.  At all  meetings of the Managers the
presence of at least four (4) Managers  shall be  necessary  and  sufficient  to
constitute a quorum for the transaction of business, and the affirmative vote of
at least a majority of the  Managers  present at any meeting at which there is a
quorum shall be the act of the Managers, except as may be otherwise specifically
provided by the Act, the Contribution Agreement, the Certificate of Formation or
this Agreement. If a quorum shall not be present at any meeting of Managers, the
Managers  present there may adjourn the meeting from time to time without notice
other  than  announcement  at the  meeting,  until a quorum  shall  be  present.
Notwithstanding any voting, quorum, or other provisions of this Agreement to the
contrary,  the affirmative  vote of at least four (4) Managers shall be required
to effect any of the following actions:

               (a) any amendment, modification or waiver of any provision of the
          Company's Certificate of Formation or this Agreement;

               (b) effecting any mergers,  consolidations or combinations of the
          Company with other entities;

               (c)  dissolving,  liquidating,  or filing  bankruptcy  or seeking
          relief under any debtor relief law;

               (d) entering into a transaction  or other action with a Member or
          Manager;

                  (e) borrowing or incurring any  indebtedness,  other than open
         accounts  payable  to  unaffiliated  third  parties,  or  granting  any
         collateral  or  security  (by way of  guaranty  or  otherwise)  for any
         indebtedness or obligation,  that exceeds (in any single transaction or
         directly related series of transactions) $25,000;

                  (f) purchasing or leasing assets or property, or entering into
         any  contract  or  obligation,  which  obligates  the Company to pay in
         excess  of  $25,000  in  one  or  any   directly   related   series  of
         installments;

               (g) selling, leasing or otherwise transferring  substantially all
          of the  Company's  assets  other  than in the  ordinary  course of the
          Company's business;

                  (h)  except  as  expressly  set forth in  Section  9.12 of the
         Contribution Agreement, allocating to the Company any costs or expenses
         that are paid or  incurred by any Member or its  affiliates  (excluding
         the Company),  or paid by the Company but reimbursable by any Member or
         its affiliates (excluding the Company), in each instance;

               (i) issuance of any ownership interest in the Company; and

                  (j)  disposition,  sale,  assignment or other  transfer by the
         Company  of any  interest  it owns in the  Company,  except  that  such
         interest may be extinguished  without the approval  required under this
         Section.

         Section 8.10.  Committees.  The Managers  may, by resolution  passed by
eighty percent (80%) of the Managers,  designate  committees,  each committee to
consist  of two or more  Managers  (at  least  one of  which  must be a  Manager
designee  of Prime  Management  and one of which must be a Manager  designee  of
LASIK),  which  committees shall have such power and authority and shall perform
such  functions  as may be  provided  in  such  resolution.  Such  committee  or
committees  shall have such name or names as may be  designated  by the Managers
and shall keep regular  minutes of their  proceedings and report the same to the
Managers when required.

         Section  8.11.  Compensation  of Managers.  The Members  shall have the
authority  to  provide,  by  unanimous  approval,  that  any  one or more of the
Managers  shall not be  compensated,  and may, by  unanimous  approval,  fix any
compensation  (which may include  expenses) they elect to pay to any one or more
of the Managers.

         Section  8.12.  Action by  Written  Consent.  Any  action  required  or
permitted  to be  taken  at any  meeting  of the  Managers  or of any  committee
designated  by the Managers may be taken  without a meeting if written  consent,
setting  forth the  action so taken,  is signed by all the  Managers  or of such
committee,  and such consent shall have the same force and effect as a unanimous
vote at a meeting.

         Section 8.13. Meetings by Conference Telephone.  Managers or members of
any committee  designated by the Managers may  participate in and hold a meeting
of the Managers or such  committee by means of  conference  telephone or similar
communications  equipment  by means of which all  persons  participating  in the
meeting  can  hear  each  other,  and  participation  in  such a  meeting  shall
constitute   presence  in  person  at  such  meeting,   except  where  a  person
participates  in the  meeting  for  the  express  purpose  of  objecting  to the
transaction  of any  business  on the ground  that the  meeting is not  lawfully
called or convened.

     Section  8.14.  Liability of Managers.  No Manager of the Company  shall be
personally  liable for any debts,  liabilities,  or  obligations of the Company,
including under a judgment, decree, or order of the court.

         Section 8.15.  Specific Power of Managers.  The Managers shall have the
authority to enter into and execute all  documents in relation to the  formation
of the Company  including,  but not limited to,  issuance of the  Certificate of
Formation and this Limited Liability Company Agreement.

                                   ARTICLE IX.

                                     NOTICES

         Section 9.1. Form of Notice.  Whenever under the provisions of the Act,
the Certificate of Formation or this Limited  Liability Company Agreement notice
is required to be given to any Manager or Member, and no provision is made as to
how such notice shall be given,  notice shall not be construed to mean  personal
notice only, but any such notice may also be given in writing,  by mail, postage
prepaid,  addressed  to such Manager or Member at such address as appears on the
books of the Company, or by telecopy, telegraph or mailgram. Any notice required
or  permitted  to be given by mail  shall be deemed  to be given  three (3) days
after it is deposited, postage prepaid, in the United States mail as aforesaid.

         Section 9.2. Waiver. Whenever any notice is required to be given to any
Manager or Member of the Company under the provision of the Act, the Certificate
of Formation or this Limited  Liability Company  Agreement,  a waiver thereof in
writing signed by the person or persons entitled to such notice,  whether signed
before or after the time stated in such waiver,  shall be deemed  equivalent  to
the giving of such notice.

                                   ARTICLE X.

                                    OFFICERS

         Any Manager may also serve as an officer of the  Company.  The Managers
may  designate  one or more persons who are not Managers of the Company to serve
as officers and may designate the titles of all officers.  The initial  officers
of the Company shall be: Ken Shifrin,  Chairman of the Board; Joe Jenkins, M.D.,
President;  Cheryl  Williams,  Vice  President,  Secretary  and Chief  Financial
Officer;  and Mark Rosenberg,  Vice President.  Unless  otherwise  provided in a
resolution of the Members or Managers the officers of the Company shall have the
powers  designated  with  respect to such  offices  under the  Delaware  Limited
Liability Company Act, and any successor statute, as amended from time-to-time.

                                   ARTICLE XI.

                                    INDEMNITY

         Section 11.1.  Indemnification.  The Company shall indemnify any person
who was or is a party or is  threatened  to be made a party  to any  threatened,
pending or  completed  action,  suit or  proceeding,  whether  civil,  criminal,
administrative, arbitrative or investigative, any appeal in such an action, suit
or  proceeding  and any  inquiry  or  investigation  that  could lead to such an
action,  suit or proceeding  (whether or not by or in the right of the Company),
by reason of the fact that such person is or was a manager, officer, employee or
agent of the  Company or is or was  serving at the  request of the  Company as a
director,  manager, officer, partner, venturer,  proprietor,  trustee, employee,
agent or similar  functionary  of another  corporation,  employee  benefit plan,
other enterprise,  or other entity, against all judgments,  penalties (including
excise and similar taxes), fines, settlements and reasonable expenses (including
attorneys'  fees and court  costs)  actually and  reasonably  incurred by him in
connection with such action,  suit or proceeding to the fullest extent permitted
by any  applicable  law,  and such  indemnity  shall inure to the benefit of the
heirs,  executors and administrators of any such person so indemnified  pursuant
to this Article XI. The right to indemnification  under this Article XI shall be
a contract  right and shall not be deemed  exclusive of any other right to which
those seeking  indemnification may be entitled under any law, bylaw,  agreement,
vote of members or disinterested managers or otherwise, both as to action in his
official  capacity  and as to action in  another  capacity  while  holding  such
office. Any repeal or amendment of this Article XI by the Members of the Company
or by changes in  applicable  law shall,  to the extent  permitted by applicable
law, be prospective only, and shall not adversely affect the  indemnification of
any person who may be indemnified at the time of such repeal or amendment.

         Section   11.2.   Indemnification   Not   Exclusive.   The   rights  of
indemnification  and reimbursement  provided for in this Article XI shall not be
deemed  exclusive  of any  other  rights  to which  any such  Manager,  officer,
employee or agent may be  entitled  under the  Certificate  of  Formation,  this
Limited  Liability  Company  Agreement,  agreement  or vote of Members,  or as a
matter of law or otherwise.

         Section  11.3.  Other  Indemnification  Clauses.   Notwithstanding  the
foregoing,   this  Article  XI  shall  not  be  construed  to   contradict   the
indemnification   provision  of  the  Contribution  Agreement.   Notwithstanding
anything  contained  herein,  this Article XI shall be ineffectual and shall not
permit or require  indemnification for all, or any, losses, costs,  liabilities,
claims or expenses arising, directly or indirectly,  from any action or omission
permitting or requiring indemnification under the Contribution Agreement; and in
no event may any  indemnity be allowed  under this  Agreement or pursuant to any
provision   of  the  Act  for  an  amount  paid  or  payable   pursuant  to  the
indemnification provisions of the Contribution Agreement.

                                  ARTICLE XII.

                                  MISCELLANEOUS

     Section 12.1. Fiscal Year. The fiscal year of the Company shall be fixed by
resolution of the Managers.

     Section 12.2.  Records.  At the expense of the Company,  the Managers shall
maintain  records and accounts of all  operations of the Company.  At a minimum,
the Company shall keep at its principal place of business the following records:

               (a) A current list of the name and last known mailing  address of
          each Member;

               (b) A current list of each Member's Membership Interest;

               (c) A copy of the Certificate of Formation and Limited  Liability
          Company Agreement of the Company, and all amendments thereto, together
          with executed copies of any powers of attorney;

               (d) Copies of the  Federal,  state,  and local income tax returns
          and reports for the Company's six most recent tax years; and

               (e)  Correct  and  complete  books and  records of account of the
          Company.

         Section 12.3. Seal. The Company may by resolution of the Managers adopt
and have a seal, and said seal may be used by causing it or a facsimile  thereof
to be  impressed  or  affixed or in any manner  reproduced.  Any  officer of the
Company shall have authority to affix the seal to any document requiring it.

     Section 12.4. Agents.  Every Manager and Officer is an agent of the Company
for the purpose of the business. The act of a Manager or Officer,  including the
execution  in the name of the Company of any  instrument  for carrying on in the
usual way the business of the Company, binds the Company.

         Section 12.5. Checks. All checks,  drafts and orders for the payment of
money,  notes  and other  evidences  of  indebtedness  issued in the name of the
Company  shall be  signed  by such  officer,  officers,  agent or  agents of the
Company  and in such  manner  as  shall  from  time to  time  be  determined  by
resolution of the Managers. In the absence of such determination by the Mangers,
such  instruments  shall  be  signed  by  the  Treasurer  or the  Secretary  and
countersigned  by the  President  or a Vice  President  of the  Company,  if the
Company has such officers.

     Section 12.6.  Deposits.  All funds of the Company shall be deposited  from
time to time to the credit of the  Company in such  banks,  trust  companies  or
other depositories as the Managers may select.

         Section  12.7.  Annual  Statement.  The Managers  shall present at each
annual  meeting,  and,  when called for by vote of the  Members,  at any special
meeting of the Members, a full and clear statement of the business and condition
of the Company.

         Section 12.8.  Financial  Statements.  As soon as practicable after the
end of each fiscal year of the  Company,  a balance  sheet as at the end of such
fiscal year,  and a profit and loss  statement  for the period  ended,  shall be
distributed  to the  Members,  along with such tax  information  (including  all
information  returns) as may be necessary for the  preparation of each Member of
its Federal,  state and local income tax returns.  The balance  sheet and profit
and loss statement  referred to in the previous  sentence may be as shown on the
Company's federal income tax return.

         Section 12.9. Binding Arbitration.  Any controversy between the parties
regarding  this  Agreement and any claims  arising out of this  Agreement or its
breach  shall be submitted  to  arbitration  by either  party.  The  arbitration
proceedings shall be conducted by a single arbitrator pursuant to the Commercial
Arbitration Rules of the American Arbitration Association. The arbitration shall
be conducted in Dallas,  Texas and the arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

                                  ARTICLE XIII.

                                   AMENDMENTS

         Section 13.1.  Amendments.  This  Agreement may be altered,  amended or
repealed and a new limited liability  company agreement may be adopted,  only in
accordance  with the  provisions  of Section 8.9,  but  otherwise at any regular
meeting or at any special meeting called for that purpose,  or by execution of a
written consent in accordance with the provisions of Section 3.8.

         Section 13.2. When Limited  Liability  Company  Agreement Silent. It is
expressly recognized that when the Limited Liability Company Agreement is silent
or in conflict with the  requirements  of the Act as to the manner of performing
any Company function, the provisions of the Act shall control.

                            [Signature page follows]


<PAGE>

                                SIGNATURE PAGE TO

                       LIMITED LIABILITY COMPANY AGREEMENT

         IN WITNESS WHEREOF,  the undersigned  Members hereby adopt this Limited
Liability  Company  Agreement as the Limited  Liability Company Agreement of the
Company, effective as of the 1st day of September, 1999.

                                           LASIK Investors, L.L.C.

                                           By: /s/ Ronald W. Barnet, M.D.
                                                 Ronald W. Barnet, M.D., manager

                                           By: /s/ David D. Dulaney, M.D.
                                                 David D. Dulaney, M.D., manager



                                           Prime Refractive Management, L.L.C.

                                           By: /s/ Cheryl Williams

                                           Printed Name: Cheryl Williams
                                           Title: Chief Financial Officer


<PAGE>
                                    EXHIBIT A

                               OWNERSHIP INTERESTS


Name                                                       Ownership Percentage

Prime Management                                                 60%

LASIK                                                            40%





                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company") and Bradley J. Wojcik and Holly M.
Wojcik, individuals residing in Granite Bay, California, and shareholders of the
Company (individually and collectively referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 16,487 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-10 and C-57 (collectively, including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $187,010.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Bradley J. and Holly M. Wojcik
                                8605 Woodrock Way
                                Granite Bay, California   95746



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>


         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:  /s/ Bradley J. Wojcik

                              Printed Name: Bradley J. Wojcik

                              Signature:  /s/ Holly M. Wojcik

                              Printed Name:  Holly M. Wojcik


Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the  "Company") and BT Alex Brown,
Inc.,  Custodian  for the  benefit of Stephen  G.  Turner,  Rollover - IRA dated
February 10, 1997, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  97,628 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-58 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $1,614,863.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         BT Alex Brown, Inc., Custodian for the benefit
                                of Stephen G. Turner, Roth - IRA
                                dated February 10, 1997
                                Seneca Capital Management
                                909 Montgomery Street, #500
                                San Francisco, California   94133




         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ BT Alex Brown c/4
                                         Stephen G. Turner IRA
                                         E. Darlene Lewis, POA VP

                              Printed Name: E. Darlene Lewis



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada corporation (the "Company") and K.J. Townsend and
E.  Townsend,  Trustees  under  The  Townsend  Trust  dated  Ausgust  30,  1995,
individuals residing in Roseville,  California,  and shareholders of the Company
("collectively and indivually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 13,987 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-8 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $158,652.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         K.J. Townsend and E. Townsend, Trustees
                                The Townsend Trust dated August 30, 1995
                                7281 Acorn Glenn Loop
                                Roseville, California   95747-8156


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/ K.J. Townsend

                              Printed Name: K.J. Townsend, Trustee under The
                                            Townsend Trust dated August 30, 1995



Company:                      Horizon Vision Center, Inc.

                                    By:/s/ David P. Bates III

                                    Printed Name:  David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada corporation (the "Company") and Beatrice Sandler,
Trustee  under the  Beatrice  Sandler  Trust,  and  shareholder  of the  Company
(collectively referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 25,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-12 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $283,571.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Beatrice Sandler
                                Trustee, Beatrice Sandler Trust
                                18607 Aceituno Street
                                San Diego, California   92128

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Beatrice Sandler

                              Printed Name:  Beatrice Sandler
                                             Trustee, Beatrice Sandler Trust



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and James Douglas Reed, an individual
residing in Folsom, California, and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,763 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-73 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,997.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         James Douglas Reed
                                157 Cascade Falls Drive
                                Folsom, California   95630


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>


S-2




         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ James Douglas Reed

                              Printed Name: James Douglas Reed



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and  Elizabeth  Jeane  Reed,  an
individual  residing in Folsom,  California,  and a  shareholder  of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,763 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-74 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,997.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Elizabeth Jean Reed
                                157 Cascade Falls Drive
                                Folsom, California   95630


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:  /s/ Elizabeth  Jeane  Reed
                              Printed Name: Elizabeth  Jeane  Reed



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and Panda  Investments,  LLC,  a
shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 16,458 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-11 and C-54 (collectively, including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $186,681.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Panda Investments, LLC
                                P.O. Box 560
                                Carmichael, California   95609-0560



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>


         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Panda  Investments,  LLC by OR
                                             (per authorization of Trustees)

                              Printed Name: Panda  Investments,  LLC
                                            Omer Rains


Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By:/s/ Cheryl Williams
                                   Cheryl Williams, Vice President

<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and Carter Nice,  an  individual
residing in Sacramento, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 15,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-7 and C-53 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $170,143.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Carter Nice
                                7729 Rio Barco Way
                                Sacramento, California   95831


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Carter Nice

                              Printed Name: Carter Nice

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company") and C.G. Neff,  Jr., an individual
residing in Zephyr Cove, Nevada and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  5,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-6 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $56,714.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         C.G. Neff, Jr.
                                600 Highway 50, Pinewild Unit 127
                                Zephyr Cove, Nevada   89448



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ C.G. Neff,  Jr.

                              Printed Name: C.G. Neff,  Jr.



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:  David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Frank T. Moormand and Luthera R.
Moorman,  individuals  residing in Sacramento,  California,  shareholders of the
Company (collectively and individually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 16,438 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-5 and C-52 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $186,454.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Frank T. or Luthera R. Moorman
                                3324 Club Lane
                                Sacramento, California   95821

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Frank T. Moormand

                              Printed Name: Frank T. Moormand

                              Signature: /s/ Luthera R. Moormand

                              Printed Name: Luthera R. Moormand



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and Kenneth V. Miselis, an individual
residing in Stockton, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 27,811 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-15 (collectively, including such shares of common stock, the "Capital Stock").
The  purchase  price for the  Capital  Stock shall be  $315,456  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Kenneth V. Miselis, M.D.
                                5762 Acorn Court
                                Stockton, California  95212



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Kenneth V. Miselis, M.D.

                              Printed Name: Kenneth V. Miselis, M.D.



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company")  and Wayne L. Marsh and Barbara K.
Koerner,  individuals  residing in Sacramento,  California,  shareholders of the
Company (collectively and individually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  14,030 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-9 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $159,140.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Wayne L. Marsh and Barbara K. Koener
                                2840 Echo Way
                                Sacramento, California   95821

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Wayne L. Marsh

                              Printed Name: Wayne L. Marsh

                              Signature: /s/ Barbara K. Koerne

                              Printed Name: Barbara K. Koerne

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title:President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and Sandra E. and Mark
R. Mandel, Trustees under Trust Agreement dated April 12, 1989, and shareholders
of the Company (collectively and individually referred to as "Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  13,942 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-20 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $158,142.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Sandra E. Mandel and Mark R. Mandel
                                Trustees under Trust Agreement dated
                                April 12, 1989
                                680 Brewer Road
                                Hillsborough, California   94010

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Sandra E. Mandel

                              Printed Name: Sandra E. Mandel, Trustees under
                                           Trust Agreement dated April 12, 1989

                              Signature: /s/ Mark R. Mandel

                              Printed Name:Mark R. Mandel, Trustees under
                                           Trust Agreement dated April 12, 1989



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

         This Stock Purchase  Agreement (this "Agreement") is entered into to be
effective   as  of  September 1, 1999 (the "Effective Time"), among PrimeSight,
L.L.C., a Delaware limited liability company ("Prime"), Horizon Vision Center,
Inc.,  a  Nevada  corporation (the "Company") and Scott B. Lee, an individual
residing in Winters, California, and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  14,000 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-4 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $158,800.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Scott B. Lee
                                26090 Country Road 34
                                Winters, California   95694


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>


S-2




         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Scott B. Lee

                              Printed Name: Scott B. Lee



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By:/s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the "Company") and Jill G. Kennedy,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 14,352 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-14 and C-89 (collectively, including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $162,793.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Jill G. Kennedy
                                1385 Yale Avenue
                                Salt Lake City, Utah   84105



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Jill G. Kennedy

                              Printed Name: Jill G. Kennedy



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and Laura G. Kennedy,  an individual
residing in Farmington, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-79 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Laura G. Kennedy
                                465 W. Honey Bee Circle
                                Farmington, Utah   84025



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/ Laura G. Kennedy

                              Printed Name: Laura G. Kennedy



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and John Paul Kennedy,  an individual
residing in Farmington, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-80 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         John Paul Kennedy
                                465 W. Honey Bee Circle
                                Farmington, Utah   84025



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John Paul Kennedy

                              Printed Name: John Paul Kennedy



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and Robert P. Kennedy,
an individual  residing in  Farmington,  Utah and a  shareholder  of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-81 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Robert P. Kennedy
                                465 W. Honey Bee Circle
                                Farmington, Utah   84025



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Laura Kennedy

                              Printed Name: Laura Kennedy, Parent Guardian for
                                Robert P. Kennedy, a Minor, Age 1 Year



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation (the "Company") and Robert J. Hardy,
M.D.,  Inc.,  Profit  Sharing  Plan and  Trust,  a  shareholder  of the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 25,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-3 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $283,571.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         [INSERT SELLER'S ADDRESS]





         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Robert J. Hardy, M.D.

                               Printed Name: Robert J. Hardy, M.D., Trustee,
                                Robert J. Hardy, M.D.,  Inc.,  Profit  Sharing
                                Plan and  Trust



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the "Company") and David S. Grodin,  an individual
residing in San Leandro, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  7,576 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-61 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $85,933.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         David S. Grodin
                                15134 Andover Street
                                San Leandro, California    94579



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ David S. Grodin

                              Printed Name: David S. Grodin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition  L.L.C., a Delaware limited  liability  company  ("Prime"),  Horizon
Vision  Center,  Inc., a Nevada  corporation  (the  "Company") and John Benjamin
Griffin,  an individual residing in Provo, Utah and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-99 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         John Benjamin Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/John R. Griffin

                              Printed Name: John R. Griffin, Parent Guardian for
                                     John Benjamin Griffin, A Minor, Age 1 week



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:  David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition  L.L.C., a Delaware limited  liability  company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and Katherine Griffin,
an  individual  residing  in  Provo,  Utah  and a  shareholder  of  the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-78 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Katherine Griffin
                                1110 East 300 South
                                Provo, Utah   84606

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John R. Griffin

                              Printed Name: John R. Griffin, Parent Guardian for
                                        Katherine Griffin, a Minor, Age 3 Years



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and John R. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-75 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         John R. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John R. Griffin

                              Printed Name: John R. Griffin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Jill C. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-76 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Jill C. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Jill C. Griffin

                              Printed Name: Jill C. Griffin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and David M. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-84 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         David M. Griffin
                                1110 East 300 South
                                Provo, Utah   84606

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ David M. Griffin

                              Printed Name: David M. Griffin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Craig S. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-87 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Craig S. Griffin
                                c/o John R. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Craig S. Griffin

                              Printed Name: Craig S. Griffin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Craig S. Griffin,  an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-87 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Craig S. Griffin
                                c/o John R. Griffin
                                3018 North Comanche Lane
                                Provo, Utah   84604

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.
Seller:                       Signature: /s/ Craig S. Griffin

                              Printed Name: Craig S. Griffin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Jolie M. Griffin,  an individual
residing in Coralville, Iowa and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-83 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Jolie M. Griffin
                                2315 Mulberry Street, #4
                                Coralville, Iowa   52241


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Jolie M. Griffin

                               Printed Name: Jolie M. Griffin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation (the "Company") and Jasmine Griffin,
an  individual  residing  in  Provo,  Utah  and a  shareholder  of  the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

         1.1 Agreement.  Upon the basis of the  representations  and warranties,
for the consideration, and subject to the terms and conditions set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized  and issued shares of the  Company's $0.01 par
value common stock presently owned by Seller and evidenced by stock certificate
number C-77 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be $19,986.00 (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Jasmine Griffin
                                1110 East 300 South
                                Provo, Utah   84606


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ John R. Griffin

                              Printed Name: John R. Griffin, Parent Guardian for
                                Jasmine Griffin, a Minor, Age 5 Years


Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition  L.L.C., a Delaware limited  liability  company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and Benjamin R.
Griffin,  an individual residing in Provo, Utah and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-86 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Benjamin Griffin
                                1110 E. 300 South
                                Provo, Utah   84606


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  David M. Griffin

                             Printed Name: David M. Griffin, Parent Guardian for
                                Benjamin R.Griffin, A Minor, Age 1 Year


Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada corporation (the "Company") and Rebekah S. Griffin, an individual
residing in Provo, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  1,762 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-85 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $19,986.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Rebekah S. Griffin
                                1110 East 300 South
                                Provo, Utah   84606



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Rebekah S. Griffin

                              Printed Name: Rebekah S. Griffin



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name:Rebekah S. Griffin

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and the Griffin
Charitable Remainder Trust, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 39,951 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-92 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $453,158.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         J. Robert Griffin, Trustee under the
                                Griffin Charitable Remainder
                                4913 Puma Way
                                Carmichael, California   95608




         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>
         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  J. Robert Griffin, Trustee

                              Printed Name: J. Robert Griffin, Trustee under the
                                        Griffin Charitable Remainder Trust


Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>

                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center, Inc., a Nevada corporation (the "Company") and J. Robert Griffin,
Trustee under the Griffin & Reed, a Medical Corporation,  401 (k) Profit Sharing
Plan, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 65,819 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-2 and C-50 (collectively,  including such shares of common stock, the "Capital
Stock").  The purchase  price for the Capital  Stock shall be  $746,576.00  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         J. Robert Griffin, Trustee under the
                                Griffin & Reed, a Medical Corporation,
                                401(k) Profit Sharing Plan
                                651 Fulton Avenue
                                Sacramento, California   95825



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  J. Robert Griffin, Trustee

                              Printed Name: J. Robert Griffin, Trustee under the
                                        Griffin & Reed, A Medical Corporation,
                                        401(k) Profit Sharing Plan

Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and Michael Rex Favero,  D.M.D.,  an
individual  residing in Sacramento,  California and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 25,000 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-1 (collectively,  including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $283,571.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Michael Rex Favero, D.M.D.
                                2237 Park Towne Circle
                                Sacramento, California   95825


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature:/s/ Michael Rex Favero,  D.M.D.

                              Printed Name: Michael Rex Favero,  D.M.D.



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the "Company") and Joyce C. Elhard,  an individual
residing  in  Mokelumne  Hill,  California  and a  shareholder  of  the  Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 11,363 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-62 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $128,889.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President


with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701


Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578




Seller:                         Joyce C. Elhard
                                18998 Penny Way
                                Mokelumne Hill, California   95245


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/  Joyce C. Elhard

                              Printed Name:  Joyce C. Elhard



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation  (the  "Company") and Donna L. Davis,  an individual
residing in Hayward, California and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 30,518 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-48 and C-68 (collectively, including such shares of common stock, the "Capital
Stock").  The  purchase  price for the  Capital  Stock  shall be  $346,161  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                     1301 Capital of Texas Highway
                           Suite C-300
                           Austin, Texas  78746
                           Attention:  President


with a copy to:            Mr. Timothy L. LaFrey
                           Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                           816 Congress Avenue, Suite 1900
                           Austin, Texas  78701


Company:                   Horizon Vision Centers, Inc.
                           14895 East 14th Street, Suite 400
                           San Leandro, California   94578




Seller:                    Donna L. Davis
                           27336 Greenhaven Road
                           Hayward, California   94542-1440



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>


S-2




         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Donna L. Davis

                               Printed Name: Donna L. Davis



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a Nevada  corporation  (the  "Company")  and  David B.  Davis,  M.D.,  an
individual  residing in Hayward,  California  and a  shareholder  of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation, 30,517 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-49 and C-67 (collectively, including such shares of common stock, the "Capital
Stock").  The  purchase  price for the  Capital  Stock  shall be  $346,150  (the
"Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                     1301 Capital of Texas Highway
                           Suite C-300
                           Austin, Texas  78746
                           Attention:  President


with a copy to:            Mr. Timothy L. LaFrey
                           Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                           816 Congress Avenue, Suite 1900
                           Austin, Texas  78701


Company:                   Horizon Vision Centers, Inc.
                           14895 East 14th Street, Suite 400
                           San Leandro, California   94578




Seller:                    David B. Davis II, M.D.
                           1237 B Street
                           Hayward, CA   94541-2915



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ David B.  Davis,  M.D.

                              Printed Name: David B.  Davis,  M.D.



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of September  1,  1999(the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc.,  a  Nevada  corporation  (the  "Company")  and  Kristine  C.  Clemens,  an
individual  residing in San Ramon,  California  and a shareholder of the Company
("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  8,983 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-21 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital Stock shall be  $101,893.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which  it  is  a  party;  and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                     1301 Capital of Texas Highway
                           Suite C-300
                           Austin, Texas  78746
                           Attention:  President


with a copy to:            Mr. Timothy L. LaFrey
                           Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                           816 Congress Avenue, Suite 1900
                           Austin, Texas  78701


Company:                   Horizon Vision Centers, Inc.
                           14895 East 14th Street, Suite 400
                           San Leandro, California   94578




Seller:                    Kristine C. Clemens
                           134 Enchanted Way
                           San Ramon, California   94583



         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Kristine  C.  Clemens

                              Printed Name: Kristine  C.  Clemens



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective as of  September 1, 1999 (the  "Effective  Time"),  among  PrimeSight,
L.L.C., a Delaware limited liability company  ("Prime"),  Horizon Vision Center,
Inc., a Nevada  corporation (the "Company") and The Corporation of the President
of the Church of Jesus Christ of Latter-Day  Saints, a Utah Corporation Sole, in
Salt Lake City, Utah and a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase from Seller,  as of the Effective Time, all
of  Seller's  shares  of  capital  stock  of  the  Company,  including,  without
limitation,  2,115 authorized and issued shares of the Company's $0.01 par value
common stock presently owned by Seller and evidenced by stock certificate number
C-88 (collectively, including such shares of common stock, the "Capital Stock").
The purchase  price for the Capital  Stock shall be  $23,990.00  (the  "Purchase
Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                         Representations and Warranties

         3.1 Representations by Seller. Seller hereby represents and warrants to
Prime that each of the following  matters is true and correct in all respects as
of the Closing Date (with the understanding  that Prime is relying materially on
each such  representation  and  warranty in entering  into and  performing  this
Agreement), which representations and warranties shall also be deemed made as of
the Effective Time and which shall survive the Closing:

                  (a) Due Authorization.  Seller has full power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed  by Seller in  connection  herewith.  This  Agreement  and each such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     (b) Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be duly authorized, validly issued and outstanding, fully paid,
non-assessable, and free of any liens, claims or encumbrances whatsoever.

                  (c) No Further  Ownership.  Immediately  following the Closing
Date, Seller does not own (i) any shares of equity or other voting securities of
the Company, (ii) any securities of the Company convertible into or exchangeable
for  shares of equity  or other  voting  securities  of the  Company,  (iii) any
options or other rights to acquire from the Company,  or any  obligation  of the
Company to issue or sell, equity or other voting  securities of the Company,  or
securities of the Company  convertible  into or exchangeable  for such equity or
voting securities,  and (iv) any equity equivalents,  interests in the ownership
or earnings, rights to participate in the election of directors or other similar
rights of or with respect to the Company.

                  (d) Claims and Proceedings.  No inquiry, action, or proceeding
has been  asserted,  instituted,  or  threatened  against  Seller to restrain or
prohibit the carrying out of the transactions  contemplated by this Agreement or
to challenge  the validity of such  transactions  or any part thereof or seeking
damages on account thereof.

         3.2  Representations by the Company.  The Company hereby represents and
warrants to Prime that each of the representations and warranties made by Seller
in Section 3.1 are true and correct in all  respects as of both the Closing Date
and the Effective Time (with the understanding  that Prime is relying materially
on the Company's  representation  and warranty in entering  into and  performing
this  Agreement),  and the  Company's  representation  and  warranty  under this
Section shall survive the Closing.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock; and

                  (c) each of them  shall  have  delivered  such  good  standing
certificates,  officer  certificates,  and similar documents and certificates as
counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
Seller,  regardless of when such claim, debt,  obligation or liability arose, is
asserted, or may have been asserted or (iii) any obligations or liabilities with
respect to any claims  arising out of actions or omissions,  that occurred prior
to the Closing Date, by any of the Company's directors, officers,  shareholders,
agents, employees, representatives, subsidiaries and/or affiliates.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified Parties may sustain,  arising out of (i) any breach or default
by Seller of any of its  representations,  warranties,  covenants or  agreements
contained in this  Agreement  or any  Transaction  Document,  or (ii) any claim,
debt,  obligation or liability of Seller,  regardless of when such claim,  debt,
obligation or liability arose, is asserted, or may have been asserted.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt  written  notice  to  Seller  and  the  Company,  as  applicable,  of the
commencement  or  assertion  of any third party  action in respect of which such
Prime Indemnified Party shall seek indemnification  hereunder. Any failure to so
notify Seller and the Company  shall not relieve  Seller or the Company from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the  failure to give such  notice  materially  and  adversely  prejudices
Seller and the  Company.  Seller and the Company  shall have the right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b)  Seller and the  Company  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) Seller and the  Company  shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) Seller and the  Company  shall not be  entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action as to which  Seller  and the  Company  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this  Agreement)  on the part of Seller or the Company,  without the prior
written consent of Seller and the Company.

                  (e) Seller and the Company  shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided  that the Prime  Indemnified  Party has agreed in writing to  reimburse
Seller  and the  Company  for the full  amount  of such  payments  if the  Prime
Indemnified  Party  is  ultimately   determined  not  to  be  entitled  to  such
indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required to  indemnify  another  party to this  Agreement in respect of
such act, omission or other matter.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Severability.  This Agreement (including,  without limitation, the
provisions  contained in ARTICLE VIII) is intended to be performed in accordance
with,  and only to the extent  permitted by, all  applicable  laws,  ordinances,
rules and  regulations.  If any provision of this Agreement,  or the application
thereof to any person or circumstance,  shall, for any reason and to any extent,
be invalid or unenforceable but the extent of the invalidity or unenforceability
does not  destroy the basis of the  bargain  between  the  parties as  contained
herein, the remainder of this Agreement and the application of such provision to
other persons or circumstances  shall not be effected thereby,  but rather shall
be enforced to the fullest extent permitted by law.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                              1301 Capital of Texas Highway
                                    Suite C-300
                                    Austin, Texas  78746
                                    Attention:  President


with a copy to:                     Mr. Timothy L. LaFrey
                                    Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                    816 Congress Avenue, Suite 1900
                                    Austin, Texas  78701


Company:                            Horizon Vision Centers, Inc.
                                    14895 East 14th Street, Suite 400
                                    San Leandro, California   94578




Seller:                             The Corporation of the President
                                    of the Church of Jesus Christ
                                    of Latter-Day Saints,
                                    a Utah Corporation Sole
                                    c/o Jill G. Kennedy
                                    1385 Yale Avenue
                                    Salt Lake City, Utah   84105


         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within  the  actual  knowledge  of any person who is or was an
officer or director of the Company  during  calendar year 1999, and any employee
of the Company who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>


         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Seller:                       Signature: /s/ Ray Anderson
                              Printed Name:  Ray Anderson, authorized agent



Company:                      Horizon Vision Center, Inc.

                                    By: /s/ David P. Bates III

                                    Printed Name: David P. Bates III

                                    Title: President



                       [Signature page for Prime follows]


<PAGE>


Prime:                       Prime/BDR Acquisition, L.L.C.

                             By: /s/ Cheryl Williams
                                   Cheryl Williams, Vice President
<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>







                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the "Company") and David P. Bates,
III and Jane A.  Bates,  individuals  residing  in San  Ramon,  California,  and
shareholders  of the  Company  (collectively  and  individually  referred  to as
"Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
22,663  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-26
and C-47 (collectively, the "Capital Stock"). The purchase price for the Capital
Stock shall be $257,063.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                              1301 Capital of Texas Highway
                                    Suite C-300
                                    Austin, Texas 78746
                                    Attention: President

with a copy to:                     Mr. Timothy L. LaFrey
                                    Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                    816 Congress Avenue, Suite 1900
                                    Austin, Texas 78701

Company:                            Horizon Vision Centers, Inc.
                                    14895 East 14th St., Suite 400
                                    San Leandro, California   94578


Seller:                             David P. and Jane A. Bates
                                    1320 Canyon Side Avenue
                                    San Ramon, California   94583

     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Secretary & Manager



Seller:                                     /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            /s/ Jane A. Bates

                                            Printed Name:  Jane A. Bates

Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>





                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>







                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and John Robert
Griffin,  M.D., Family Revocable Trust dated February 8, 1991, and a shareholder
of the Company ("Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
23,939  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock certificate  number C- 22
and C-59 (collectively, the "Capital Stock"). The purchase price for the Capital
Stock shall be $271,537.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                              1301 Capital of Texas Highway
                                    Suite C-300
                                    Austin, Texas 78746
                                    Attention: President

with a copy to:                     Mr. Timothy L. LaFrey
                                    Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                    816 Congress Avenue, Suite 1900
                                    Austin, Texas 78701

Company:                            Horizon Vision Centers, Inc.
                                    14895 East 14th Street, Suite 400
                                    San Leandro, California   94578

Seller:                             John Robert Griffin, M.D., Trustee
                                    Family Revocable Trust
                                    dated February 8, 1991
                                    4913 Puma Way
                                    Carmichael, California   95608

     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President



Seller:                                  /s/ John Robert Griffin, M.D., Trustee

                          Printed Name: John Robert Griffin, M.D., Trustee under
                                        the John Robert Griffin, M.D. Family
                                        Revocable Trust dated February 1, 1991


Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>





                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>







                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the "Company") and Mark R. Mandel,
M.D.,  Trustee under Trust  Agreement dated April 12, 1989, and a shareholder of
the Company ("Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
79,914  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock certificate  number C-24,
C-36,  C-41, C-44 and C-95  (collectively,  the "Capital  Stock").  The purchase
price for the Capital Stock shall be $906,453.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                           1301 Capital of Texas Highway
                                 Suite C-300
                                 Austin, Texas 78746
                                 Attention: President

with a copy to:                  Mr. Timothy L. LaFrey
                                 Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                 816 Congress Avenue, Suite 1900
                                 Austin, Texas 78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578


Seller:                         Mark R. Mandel, M.D., Trustee
                                under Trust Agreement
                                dated April 12, 1989
                                680 Brewer Road
                                Hillsborough, California   94010


     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President



Seller:                                  /s/ Mark R. Mandel, M.D.

                                            Printed Name:  Mark R. Mandel, M.D.
                                                Trustee under Trust Agreement
                                                dated April 12, 1989



Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>





                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>
                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>







                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision  Center,  Inc.,  a Nevada  corporation  (the  "Company")  and  Bradley J.
Sandler,   M.D.  an  individual  residing  in  Suisun  City,  California  and  a
shareholder of the Company ("Seller").

The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
44,780  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-97
(collectively,  the "Capital  Stock").  The purchase price for the Capital Stock
shall be $507,933.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing this Agreement):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

            Representations and Warranties of the Company and Seller

         Seller and the Company hereby  represent and warrant to Prime,  jointly
and  severally,  that each of the  following  matters is true and correct in all
respects as of the Closing  Date (with the  understanding  that Prime is relying
materially  on each  such  representation  and  warranty  in  entering  into and
performing this Agreement),  which  representations and warranties shall also be
deemed  made as of the  Effective  Time and which  shall  survive  the  Closing;
provided,  however,  that all  representations  and  warranties  made by  Seller
hereunder shall be deemed made by Seller only to the actual knowledge of Seller.

         3.1 Due  Organization.  The Company is a  corporation  duly  organized,
validly existing, and in good standing under the laws of the State of Nevada and
has full power and  authority to carry on its business as now  conducted  and as
proposed to be conducted. The Company is qualified to do business and is in good
standing  in the states set forth on  Schedule  3.1(a)  attached  hereto,  which
states represent every jurisdiction where such qualification is required for the
conduct of the Company's business as conducted on the Closing Date. Complete and
correct copies of the Company's Articles of Incorporation,  Bylaws, all board of
directors'  resolutions,  all  shareholders'  resolutions,  and  all  amendments
thereto,  have been  delivered to Prime.  Schedule  3.1(b) sets forth a true and
complete  list,  as of the Closing  Date, of all of the holders of any equity or
other ownership interest in the Company or of any right to obtain, by conversion
or otherwise,  and regardless of whether  presently  exercisable,  any equity or
other  ownership  interest in the  Company;  in each case showing the number and
type of interest  or right held.  Schedule  3.1(b) also  identifies  each of the
persons  listed   therein  that  is  a  physician  or  other  licensed   medical
professional,  and describes  each such  person's  license(s)  and  professional
title. Except as set forth on Schedule 3.1(b),  immediately prior to the Closing
Date there are outstanding (i) no shares of equity or other voting securities of
the Company,  (ii) no securities of the Company convertible into or exchangeable
for shares of equity or other voting securities of the Company, (iii) no options
or other rights to acquire from the Company or Seller,  and no obligation of the
Company or Seller to issue or sell, any equity or other voting securities of the
Company or any securities of the Company  convertible  into or exchangeable  for
such equity or voting securities,  and (iv) no equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar  rights of or with respect to the Company.  Immediately  following
the Closing of this transaction and the closings of the Related Acquisitions (as
hereinafter  defined),  Prime will own sixty  percent (60%) of all of the voting
equity  securities of the Company (after  assuming the  conversion,  exchange or
exercise of any and all securities or rights  convertible  into, or exchangeable
or exercisable for, voting equity  securities of the Company),  and all of those
persons and entities listed on Schedule 3.1(b) will own, in the aggregate, forty
percent  (40%) of all of the voting  equity  securities  of the  Company  (after
assuming  the  conversion,  exchange or exercise  of any and all  securities  or
rights  convertible  into, or  exchangeable  or exercisable  for,  voting equity
securities of the Company).  The Capital Stock transferred by Seller to Prime at
the Closing,  as well as all other capital stock of the Company  transferred  to
Prime in the Related Acquisitions,  will be duly authorized,  validly issued and
outstanding,  fully  paid,  non-assessable,  and free of any  liens,  claims  or
encumbrances whatsoever.

         3.2  Subsidiaries.  Except as set  forth on  Schedule  3.2  (reflecting
ownership  interests  and the nature of such  interests),  the Company  does not
directly or indirectly  have (or possess any options or other rights to acquire)
any  subsidiaries or any direct or indirect  ownership  interests in any person,
business,  corporation,  partnership,  limited liability  company,  association,
joint venture, trust, or other entity.

         3.3 Due  Authorization.  Each of the  Company and Seller has full power
and  authority to enter into and perform  this  Agreement  and each  Transaction
Document  required  to be  executed  by the  Company  or  Seller  in  connection
herewith.  The execution,  delivery,  and performance of this Agreement and each
such  Transaction  Document has been duly authorized by all necessary  action of
the Company,  its directors,  its officers and its shareholders.  This Agreement
and each such  Transaction  Document  has been  duly and  validly  executed  and
delivered  by the  Company  and  Seller  and  constitutes  a valid  and  binding
obligation  of the  Company  and  Seller,  enforceable  against  each of them in
accordance  with its terms.  The execution,  delivery,  and  performance of this
Agreement,  and each  Transaction  Document  required  herein to be  executed by
Seller  and/or the Company do not (a) violate any  federal,  state,  county,  or
local law,  rule,  or  regulation  applicable  to the Company,  the Business (as
hereinafter defined),  the Company's assets or the Capital Stock, (b) violate or
conflict with, or permit the cancellation of, any agreement to which the Company
is a party,  or by which the Company or its properties  are bound,  or result in
the creation of any lien, security interest,  charge, or encumbrance upon any of
such  properties or the upon the Capital Stock,  (c) permit the  acceleration of
the maturity of any  indebtedness of Seller or the Company,  or any indebtedness
secured by the Capital  Stock or by the property of the Company,  or (d) violate
or conflict with any provision of the  organizational  documents of the Company.
No action,  consent,  waiver or approval of, or filing with, any federal, state,
county or local  governmental  authority is required by Seller or the Company in
connection  with the execution,  delivery,  or performance of this Agreement (or
any Transaction Document).

         3.4  Financial  Statements.  The  unaudited  balance  sheet and  income
statement  of the  Company as of and for each of the years  ended March 31, 1998
and 1999, and the unaudited balance sheet and income statement of the Company as
of and for  the  three  (3)  months  ended  June  30,  1999  (collectively,  the
"Financial  Statements")  are  attached  hereto  as  Exhibit  A.  The  Financial
Statements have been prepared in accordance with generally  accepted  accounting
principles  consistently  applied ("GAAP") (except as specifically noted therein
or in Schedule  3.4) and fairly  present the  financial  position and results of
operations  of the  Company  as of the  indicated  dates  and for the  indicated
periods.  Except for liabilities  incurred in the ordinary course of business or
disclosed  in  Schedule  3.4,  and except to the extent  specifically  and fully
reflected in the Financial Statements  (including the notes thereto),  as of the
Closing Date, the Company has no claims,  debts,  liabilities,  or  obligations,
whether known or unknown, absolute,  contingent or otherwise (including, but not
limited to,  federal,  state,  and local taxes,  any sales taxes,  use taxes and
property  taxes,  any taxes arising from the  transactions  contemplated by this
Agreement and any liabilities arising from any litigation or civil,  criminal or
regulatory  proceeding  involving or related to the  Company,  its assets or the
Business).  The  Company and Seller each agree to  indemnify  and hold  harmless
Prime  and its  affiliates  from and  against  any and all such  claims,  debts,
liabilities and obligations.  Except as set forth in Schedule 3.4 hereto,  since
June 30,  1999 there has been no  material  adverse  change in the assets of the
Company, the Business, or the results of operations or financial position of the
Company.

         3.5 Conduct of Business;  Certain Actions.  As used herein,  "Business"
means all of the business  conducted  by the  Company,  which shall be deemed to
include  all  refractive  surgery  modalities,  now  performed,  offered or made
available, including, without limitation,  implantable contact lenses, instromal
corneal  rings,  laser  in  situs  keratomileusis  photorefractive  keratectomy,
automated lemellar  keratoplasty,  radial keratotomy,  astigmatic keratotomy and
similar procedures.  Except as set forth on Schedule 3.5 attached hereto,  since
June 30, 1999,  the Company has  conducted  its Business and  operations  of the
Business in the ordinary  course and consistent  with its past practices and has
not (a)  purchased  or retired  any  indebtedness,  or  purchased,  retired,  or
redeemed any  ownership  interest  from,  any  director,  officer,  shareholder,
employee or affiliate of the Company,  or engaged in any other  transaction that
involves or requires  distributions of money or other assets from the Company to
any director, officer, shareholder, employee or affiliate of the Company if such
other  transaction  is not done in the  ordinary  course of business  and is not
consistent with past practices of the Company, (b) increased the compensation of
any  directors,  officers,  employees,  agents,  contractors,  vendors  or other
parties,  except for wage and salary  increases  made in the ordinary  course of
business and consistent with the past practices of the Company, (c) made capital
expenditures  exceeding  $10,000  individually or $25,000 in the aggregate,  (d)
sold any asset (or any group of related assets) in any transaction (or series of
related  transactions)  in which the purchase price or book value for such asset
(or group of related assets) exceeded  $10,000,  (e) discharged or satisfied any
lien or encumbrance or paid any obligation or liability, absolute or contingent,
other than  current  liabilities  incurred  and paid in the  ordinary  course of
business,  (f) made or guaranteed any loans or advances to any party whatsoever,
(g) suffered or permitted any lien, security interest,  claim,  charge, or other
encumbrance to arise or be granted or created against or upon any of its assets,
real or personal,  tangible or intangible, (h) canceled, waived, or released any
of its  debts,  rights,  or  claims  against  third  parties,  (i)  amended  its
organizational  documents, (j) made or paid any severance or termination payment
to any director, officer, employee, agent, contractor, vendor or consultant, (k)
made any  change  in its  method  of  accounting,  (l) made  any  investment  or
commitment  therefor  in  any  person,   business,   corporation,   association,
partnership,  limited liability company, joint venture,  trust, or other entity,
(m) made, entered into, amended, or terminated any written employment  contract,
created,  made,  amended,  or  terminated  any  bonus,  stock  option,  pension,
retirement,  profit sharing,  or other employee benefit plan or arrangement,  or
withdrawn  from any  "multi-employer  plan" (as defined in the Internal  Revenue
Code of 1986, as amended (the "Code")) so as to create any liability under ERISA
(as  hereinafter  defined) to any person or entity,  (n) amended,  terminated or
experienced a termination of any material contract, agreement, lease, franchise,
or license  to which it is a party,  (o) made any  distributions,  in cash or in
kind, to its  shareholders,  or to any person or entity related to or affiliated
therewith,  in any  capacity,  except  such  distributions  as are  made  in the
ordinary course of the Company's  business  consistent with past practices,  (p)
entered into any other material  transactions  except in the ordinary  course of
business, (q) entered into any contract, commitment, agreement, or understanding
to do any acts described in the foregoing  clauses (a)-(p) of this Section,  (r)
suffered any material  damage,  destruction,  or loss (whether or not covered by
insurance) to any assets,  (s) experienced any strike,  slowdown,  or demand for
recognition by a labor  organization by or with respect to any of its employees,
or (t)  experienced  or effected any  shutdown,  slow-down,  or cessation of any
operations conducted by, or constituting part of, it.

         3.6 Assets;  Licenses,  Permits,  etc.  Except as set forth on Schedule
3.6(a), the Company has good and marketable title to all of its assets, free and
clear  of  all  liens,  security  interests,  claims,  rights  of  another,  and
encumbrances  of any kind  whatsoever.  The  assets of the  Company  are in good
operating  condition and repair,  subject to ordinary wear and tear, taking into
account the  respective  ages of the  properties  involved  and are all that are
necessary for the conduct of the Business. Attached hereto as Schedule 3.6(b) is
a list and description of all federal,  state,  county,  and local  governmental
licenses,  certificates,  certificates of need,  permits,  waivers,  filings and
orders  held or applied  for by the Company and used or relied on (or to be used
or relied on) in  connection  with the  Business  ("Permits").  The  Company has
complied  in all  material  respects,  and the Company is in  compliance  in all
material  respects,  with the  terms  and  conditions  of any such  Permits.  No
additional  Permit  is  required  from  any  federal,  state,  county,  or local
governmental  agency or body  thereof  in  connection  with the  conduct  of the
Business.  No claim has been made by any  governmental  authority  (and,  to the
knowledge of Seller and the Company,  no such claim has been  threatened) to the
effect that a Permit not possessed by the Company is necessary in respect of the
Business.

         3.7      Environmental Issues.

                  (a) For purposes of this  Agreement,  the term  "environmental
laws"  shall  mean  all  laws  and  regulations  relating  to  the  manufacture,
processing,  distribution,  use, treatment,  storage,  disposal,  transport,  or
handling, or the emission, discharge, or release, of any pollutant, contaminant,
chemical,  or industrial  toxic or hazardous  substance or waste,  and any order
related thereto.

                  (b) The Company has complied in all material respects with and
obtained  all  authorizations  and made all filings  required by all  applicable
environmental laws. The properties occupied or used by the Company have not been
contaminated with any hazardous wastes, hazardous substances, or other hazardous
or toxic  materials  in  violation  of any  applicable  environmental  law,  the
violation of which could have a material  adverse  impact on the Business or the
financial position of the Company.

                  (c) The  Company has not  received  any notice from the United
States  Environmental  Protection  Agency that it is a  potentially  responsible
party under the Comprehensive Environmental Response, Compensation and Liability
Act  ("Superfund  Notice"),  any  citation  from  any  federal,  state  or local
governmental  authority for non-compliance with its requirements with respect to
air, water or environmental pollution, or the improper storage, use or discharge
of any  hazardous  waste,  other  waste or  other  substance  or other  material
pertaining to its business  ("Citations") or any written notice from any private
party alleging any such  non-compliance;  and there are no pending or unresolved
Superfund  Notices,  Citations or written notices from private parties  alleging
any such non-compliance.

         3.8  Intellectual  Property Rights.  There are no patents,  trademarks,
trade names, or copyrights, and no applications therefor, owned by or registered
in the name of the Company or in which the Company  has any right,  license,  or
interest.  The  Company  is not a party  to any  license  agreement,  either  as
licensor or licensee, with respect to any patents,  trademarks,  trade names, or
copyrights.  The Company has not received any notice that it is  infringing  any
patent, trademark, trade name, or copyright of others.

         3.9  Compliance  with Laws. To the knowledge of the Company and Seller,
the  Company  has  complied  in all  material  respects,  and the  Company is in
compliance in all material respects,  with all federal, state, county, and local
laws, rules,  regulations and ordinances  currently in effect. No claim has been
made or  threatened  by any  governmental  authority  against the Company to the
effect that the business conducted by the Company fails to comply in any respect
with any law, rule, regulation, or ordinance.

         3.10  Insurance.  Attached  hereto  as  Schedule  3.10 is a list of all
policies of fire, liability, business interruption, and other forms of insurance
(including,  without  limitation,  professional  liability  insurance)  and  all
fidelity  bonds held by or applicable to the Company at any time within the past
three (3) years,  which  schedule  sets forth in respect of each such policy the
policy name, policy number,  carrier, term, type of coverage,  deductible amount
or self-insured retention amount, limits of coverage, and annual premium. To the
knowledge of the Company and Seller,  no event directly  relating to the Company
has occurred  which will result in a retroactive  upward  adjustment of premiums
under any such policies or which is likely to result in any  prospective  upward
adjustment in such premiums.  There have been no material changes in the type of
insurance  coverage  maintained by the Company  during the past three (3) years,
including without  limitation any change which has resulted in any period during
which the Company had no insurance coverage.  Excluding insurance policies which
have  expired and been  replaced,  no  insurance  policy of the Company has been
canceled  within  the last three (3) years and no threat has been made to cancel
any insurance policy of the Company within such period.

         3.11 Employee  Benefit  Matters.  Except as set forth on Schedule 3.11,
the  Company  does not  maintain  nor does it  contribute  nor is it required to
contribute to any "employee welfare benefit plan" (as defined in section 3(1) of
the  Employee  Retirement  Income  Security Act of 1974 (and any sections of the
Code amended by it) and all regulations promulgated thereunder, as the same have
from time to time been amended ("ERISA")) or any "employee pension benefit plan"
(as defined in ERISA).  The Company  does not  presently  maintain and has never
maintained,  or had any  obligation of any nature to  contribute  to, a "defined
benefit plan" within the meaning of the Code.

         3.12 Contracts and  Agreements.  Attached  hereto as Schedule 3.12 is a
list of all written or oral contracts, commitments, leases, and other agreements
(including, without limitation, all promissory notes, loan agreements, and other
evidences  of  indebtedness,  mortgages,  deeds of trust,  security  agreements,
pledge agreements,  service  agreements,  and similar agreements and instruments
and all confidentiality  agreements) to which the Company is a party or by which
the  Company or its  properties  are bound,  pursuant  to which the  obligations
thereunder of any party thereto are, or are contemplated as being, in respect of
any such individual contracts,  commitments,  leases, or other agreements during
any year during the term  thereof,  $25,000 or greater,  or which are  otherwise
material to the Business  (collectively  the  "Contracts"  and  individually,  a
"Contract").  The Company is not and, to the best  knowledge  of the Company and
Seller,  no other party thereto is in default (and no event has occurred  which,
with the passage of time or the giving of notice,  or both,  would  constitute a
default by the Company or, to the best  knowledge of the Company and Seller,  by
any other  party  thereto)  under any  Contract.  The Company has not waived any
material  right under any  Contract,  and no consents or  approvals  (other than
those  obtained in writing and delivered to Prime prior to Closing) are required
under  any  Contract  in  connection  with  the  sale of  Capital  Stock  or the
consummation  of the  transactions  contemplated  hereby.  The  Company  has not
guaranteed any obligation of any other person or entity.

         3.13 Claims and Proceedings. Attached hereto as Schedule 3.13 is a list
and description of all claims, actions, suits,  proceedings,  and investigations
pending or, to the knowledge of the Company and Seller,  threatened  against the
Company,  at law or in  equity,  or before or by any court,  municipal  or other
governmental department,  commission, board, agency, or instrumentality.  Except
as set forth on Schedule 3.13  attached  hereto,  none of such claims,  actions,
suits,  proceedings,  or investigations  will result in any liability or loss to
the Company  which  (individually  or in the  aggregate)  is  material,  and the
Company  has not  been,  and the  Company  is not  now,  subject  to any  order,
judgment,  decree,  stipulation,  or consent of any court, governmental body, or
agency.  No inquiry,  action,  or proceeding has been asserted,  instituted,  or
threatened  against the Company or Seller to restrain or prohibit  the  carrying
out of the  transactions  contemplated  by this  Agreement or to  challenge  the
validity of such  transactions or any part thereof or seeking damages on account
thereof.

         3.14 Taxes.  All federal,  foreign,  state,  county,  and local income,
gross receipts, excise, property,  franchise,  license, sales, use, withholding,
and other tax  (collectively,  "Taxes")  returns,  reports,  and declarations of
estimated tax  (collectively,  "Returns") which were required to be filed by the
company on or before the date hereof have been filed within the time  (including
any  applicable  extensions)  and in the manner  provided  by law,  and all such
Returns are true and correct in all material respects and accurately reflect the
Tax  liabilities  of the Company.  The Company has provided Prime with copies of
all returns  filed for and during the years ended 1998,  1997 and (to the extent
an extension was filed for any return for the year ended 1998) 1996.  All Taxes,
assessments,  penalties,  and  interest  which have become due  pursuant to such
Returns have been paid or adequately  accrued in the Financial  Statements.  The
provisions for Taxes  reflected on the balance sheet  contained in the Financial
Statements are adequate to cover all of the Company's  estimated Tax liabilities
for the respective  periods then ended and all prior periods.  As of the Closing
Date,  the  Company  will not owe any Taxes for any period  prior to the Closing
which  are  not  reflected  on  the  Financial  Statements,   except  for  Taxes
attributable  to the  operations  of the Company  between  June 30, 1999 and the
Closing  Date.  The Company has not executed any presently  effective  waiver or
extension of any statute of limitations  against  assessments  and collection of
Taxes.  There  are  no  pending  or  threatened  claims,  assessments,  notices,
proposals  to assess,  deficiencies,  or audits  (collectively,  "Tax  Actions")
against  the Company  with  respect to any Taxes owed or  allegedly  owed by the
Company. There are no tax liens on any of the assets of the Company.  Proper and
accurate  amounts  have been  withheld  and  remitted by the Company from and in
respect of all persons  from whom it is required by  applicable  law to withhold
for all  periods  in  compliance  with  the tax  withholding  provisions  of all
applicable laws and  regulations.  The Company is not a party to any tax sharing
agreement.

         3.15 Personnel. Attached hereto as Schedule 3.15 is a list of names and
current annual rates of compensation of the officers, employees or agents of the
Company who are necessary  for the operation of the Business (the  "Employees").
Except as set forth on  Schedule  3.15,  there  are no  bonus,  profit  sharing,
percentage  compensation,  company automobile,  club membership,  and other like
benefits,  if any, paid or payable by the Company to any Employees from December
31, 1998 through the Closing Date. Schedule 3.15 attached hereto also contains a
brief   description  of  all  material   terms  of  employment   agreements  and
confidentiality  agreements  to which the  Company is a party and all  severance
benefits which any director,  officer,  Employee or sales  representative of the
Company is or may be  entitled to receive.  The Company has  delivered  to Prime
accurate and complete copies of all such employment agreements,  confidentiality
agreements, and all other agreements,  plans, and other instruments to which the
Company  is a party and under  which  its  employees  are  entitled  to  receive
benefits of any nature.  There is no pending or threatened  (i) labor dispute or
union  organization  campaign  relating to the Company,  (ii) claims against the
Company by any  employees  of the  Company  (other than those  certain  Workers'
Compensation  claims   specifically   described  on  Schedule  3.13),  or  (iii)
terminations,  resignations or retirements of any employees of the Company. None
of  the  employees  of  the  Company  are  represented  by any  labor  union  or
organization. There is no unfair labor practice claim against the Company before
the National Labor Relations Board or any strike, labor dispute,  work slowdown,
or work stoppage pending or threatened against or involving the Company.

         3.16 Business  Relations.  The Company has no reason to believe and has
not been  notified  that any  supplier or customer of the Company  will cease or
refuse  to do  business  with the  Company  in the  same  manner  as  previously
conducted  with the  Company  as a result  of or within  one (1) year  after the
consummation  of  the  transactions  contemplated  hereby,  to the  extent  such
cessation or refusal might affect the Business. The Company has not received any
notice  of any  disruption  (including  delayed  deliveries  or  allocations  by
suppliers) in the availability of the materials or products used by the Company.

         3.17 Working  Capital.  Except as set forth on Schedule  3.17  attached
hereto,  all of  the  accounts,  notes,  and  loans  receivable  (the  "Accounts
Receivable")  reflected in the Financial  Statements,  or arising since June 30,
1999, arose from transactions  occurring in the ordinary course of the Company's
business as previously  conducted,  are bona fide and represent  amounts validly
due,  subject to offsets or  defenses.  Except for  accounts  payable  and other
accrued expenses incurred in the ordinary course of the Company's business since
June 30, 1999 and consistent  with past  practices of the Company,  there are no
liabilities  of  the  Company  other  than  those  reflected  in  the  Financial
Statements.   Adequate  provision  has  been  made  for  uncollectible  Accounts
Receivable.  Since  June 30,  1999,  the  Company  has  collected  its  Accounts
Receivable  and has paid or performed all  liabilities  and  obligations  of the
Company in the ordinary  course,  consistent  with past  practices.  The Working
Capital (as hereinafter  defined) of the Company existing on the Closing Date is
equal to or greater than $100,000.

         3.18 Agents.  Except as set forth on Schedule 3.18 attached hereto, the
Company has not  designated  or appointed  any person  (other than the Company's
employees and officers) or other entity to act for it or on its behalf  pursuant
to any power of attorney or any agency which is presently in effect.

         3.19  Indebtedness To and From Directors,  Officers,  Shareholders  and
Employees.  The Company does not owe any  indebtedness  to any of its directors,
officers, shareholders, employees or affiliates, or have indebtedness owed to it
from any of its  directors,  officers,  shareholders,  employees or  affiliates,
excluding  indebtedness  for travel  advances or similar  advances  for expenses
incurred on behalf of and in the ordinary  course of business of the Company and
consistent with the Company's past  practices.  As of the Effective Time and the
Closing  Date all amounts due the Company from any of its  directors,  officers,
employees or affiliates (or any of their family  members) shall have been repaid
in full.

         3.20 Commission Sales  Contracts.  Except as disclosed in Schedule 3.20
attached hereto,  the Company does not employ or have any relationship  with any
individual,  corporation,  partnership,  or other entity whose compensation from
the Company is in whole or in part determined on a commission basis.

         3.21 Certain  Consents.  Except as set forth on Schedule  3.21 attached
hereto,  there are no consents,  waivers,  or approvals  required to be executed
and/or  obtained  by the  Company  from  third  parties in  connection  with the
execution,  delivery,  and  performance  of this  Agreement  or any of the other
contracts, documents, instruments or agreements to be entered into in connection
with  or as  contemplated  by this  Agreement  (all of  which  are  collectively
referred to as the "Transaction Documents").

         3.22 Brokers.  The Company has not engaged,  or caused any liability to
be incurred to, any finder,  broker,  or sales agent (and has not paid, and will
not pay,  any  finders  fee or  similar  fee or  commission  to any  person)  in
connection with the execution, delivery, or performance of this Agreement or the
transactions contemplated hereby.

         3.23 Interest in Competitors,  Suppliers, and Customers.  Except as set
forth on Schedule 3.23 attached hereto, neither the Company nor any affiliate of
the  Company,  and to the  knowledge  of the Company and  Seller,  no  director,
officer,  employee or affiliate of the Company or any affiliate of any director,
officer, employee or affiliate of the Company, has any ownership interest in any
competitor,  customer or supplier  of the  Company or any  property  used in the
operation of the Business.

         3.24 Warranties.  Except as set forth on Schedule 3.24, the Company has
not made any  warranties  or  guarantees  to third  parties  with respect to any
products  sold or services  rendered by it. Except as set forth on Schedule 3.24
attached hereto, no claims for breach of product or service warranties have been
made against the Company since January 1, 1996.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

     (b) execute and deliver each of the Transaction  Documents to which it is a
party; and

                  (c)  deliver   such  good   standing   certificates,   officer
certificates,  and similar  documents and certificates as counsel for Seller may
reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit B;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  C,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  D,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of (i) any breach or default by Seller or the Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction  Document,  (ii) any claim, debt,  obligation or liability of
the Company,  not  specifically and fully reflected by item and amount on either
Schedule 3.4 or in the  Financial  Statements,  that is or may be asserted  with
respect to any acts or omissions  occurring,  or circumstances  existing,  on or
prior to the Closing  Date,  except for  liabilities  incurred  in the  ordinary
course of business,  or (iii) any obligations or liabilities with respect to any
claims  arising out of actions or omissions,  that occurred prior to the Closing
Date,  by  any of  the  Company's  directors,  officers,  shareholders,  agents,
employees, representatives, subsidiaries and/or affiliates.

                  (b) Seller  agrees to indemnify  and hold harmless each of the
Prime  Indemnified  Parties  from and against any and all  Indemnified  Costs in
connection with the  commencement  or assertion of any third-party  action which
any of the Prime Indemnified  Parties may sustain,  arising out of any breach or
default  by  Seller  of any of its  representations,  warranties,  covenants  or
agreements contained in this Agreement or any Transaction Document.

                  (c) Notwithstanding the foregoing,  no Prime Indemnified Party
shall be entitled to assert any claim for indemnification under this Section 6.1
unless and until such time as all claims of all Prime Indemnified Parties, taken
together,  exceed  $10,000  in the  aggregate,  at which time all claims of such
Prime  Indemnified  Parties  may  be  asserted  individually  or in  combination
(beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section 6.1 shall be limited to the aggregate  Purchase Price received by Seller
under this Agreement,  plus the greater of (a) the value of all remaining equity
interests  which  Seller  holds in the Company at the time of Closing or (b) the
value of all remaining equity interests which Seller holds in the Company at the
time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

         Notwithstanding  the foregoing,  no Seller  Indemnified  Party shall be
entitled to assert any claim for  indemnification  under this Section 7.1 unless
and until such time as all claims of such Seller Indemnified Party, individually
and not in combination with other Seller Indemnified Parties,  exceed $25,000 in
the aggregate,  at which time all claims of such Seller Indemnified Party may be
asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding any transfers governed by Section 9.3), (iii)
relocation  of Seller's  primary  residence  outside of a two hundred (200) mile
radius of the center or facility at which Seller primarily renders services,  or
(iv) if Seller is a physician or other  practicing  licensed  professional,  the
performance by Seller, during any one-month period, of greater than thirty (30%)
of his or her  professional  medical  activities  outside of a two hundred (200)
mile radius of the center or facility  primarily utilized by Seller prior to the
date  of  this  Agreement;  the  Seller's  executor,   administrator,   trustee,
custodian,   receiver   or  other   legal  or   personal   representative   (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or relocation of primary residence or practice, as the case may be, within which
time  it may  require  that  the  Company  purchase  (subject  to the  remaining
provisions  of this  subsection)  all of Seller's  capital stock of the Company,
upon the terms and conditions  hereinafter  set forth,  by giving notice of such
election in writing to the  Company.  The Company  may, in its sole  discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

         9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital Contributions.  Without in any way limiting or
qualifying  the  representation  and warranty  with  respect to Working  Capital
contained in Section 3.17, all parties to this Agreement  acknowledge  and agree
that no  shareholder  of the  Company,  or any other party,  has any  obligation
existing on the Closing Date to make a capital contribution to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                  IN ADDITION, SHARES MAY BE TRANSFERRED ONLY IN COMPLIANCE WITH
                  CERTAIN  CONDITIONS  SPECIFIED  IN A  CERTAIN  STOCK  PURCHASE
                  AGREEMENT  DATED EFFECTIVE AS OF SEPTEMBER 1, 1999, A COMPLETE
                  AND CORRECT COPY OF WHICH IS AVAILABLE  FOR  INSPECTION AT THE
                  PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE  FURNISHED TO THE
                  HOLDER HEREOF UPON WRITTEN REQUEST AND WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4 Invalid Provisions.  If any provision of this Agreement is held to
be  illegal,  invalid,  or  unenforceable  under  present or future  laws,  such
provision shall be fully severable, this Agreement shall be construed as if such
illegal,  invalid, or unenforceable provision had never comprised a part of this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                           1301 Capital of Texas Highway
                                 Suite C-300
                                 Austin, Texas 78746
                                 Attention: President

with a copy to:                  Mr. Timothy L. LaFrey
                                 Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                 816 Congress Avenue, Suite 1900
                                 Austin, Texas 78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578


Seller:                         Bradley J. Sandler, M.D.
                                403 Calle De Caballo
                                Suisun City, CA   94585-1501


     Each party may change its  address for  purposes of this  Section by proper
notice to the other parties.

     10.7 Survival of Representations,  Warranties, and Covenants. Regardless of
any investigation at any time made by or on behalf of any party hereto or of any
information any party may have in respect  thereof,  all covenants,  agreements,
representations,  and  warranties  made  hereunder  or  pursuant  hereto  or  in
connection with the transactions contemplated hereby shall survive the Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge"  is used in this  Agreement in reference to (i) Prime,  it
shall mean such items as are within the actual knowledge of Ken Shifrin,  Cheryl
Williams,  Mark  Rosenberg and Dr.  Jenkins and (ii) the Company,  it shall mean
such items as are within the actual  knowledge  of the  officers  of the Company
holding office immediately prior to the Closing, and any employee of the Company
who remains an employee of the Company after the Closing.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

         10.12   Counterparts.   This  Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title:Secretary & Manager



Seller:                                  /s/ Bradley J. Sandler, M.D.

                                         Printed Name:  Bradley J. Sandler, M.D.



Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>





                                TABLE OF EXHIBITS

EXHIBIT A:        Financial Statements
EXHIBIT B:        Form of Exclusive Use Agreement
EXHIBIT C:        Form of Assignment and Security Agreement
EXHIBIT D:        Form of Amended and Restated Bylaws of Seller

<PAGE>









                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>






                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada corporation (the "Company") and D. Brent Reed and
Carellyn S. Reed, individuals residing in Folsom, California shareholders of the
Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
73,520  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-25
and C-94 (collectively, the "Capital Stock"). The purchase price for the Capital
Stock shall be $833,926.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578


Seller:                         D. Brent Reed and Carellyn S. Reed
                                157 Cascade Falls Drive
                                Folsom, California   95630

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]


<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President



Seller:                                  /s/ D. Brent Reed

                                         Printed Name:   D. Brent Reed

                                         /s/ Carellyn S. Reed

                                         Printed Name:  Carellyn S. Reed


Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>




                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller

<PAGE>









                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>






                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the  "Company") and Severin Family
Trust, and shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
39,369  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock certificate  number C-27,
C-35, C-40, and C-45 (collectively, the "Capital Stock"). The purchase price for
the Capital Stock shall be $446,557.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578


Seller:                         Severin Family Trust
                                Sanford L. Severin, Trustee
                                1040 McCauley Road
                                Danville, California   94526

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]


<PAGE>

                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President



Seller:                                  /s/ Sanford L. Severin
                                         Printed Name:   Sanford L. Severin,
                                                Trustee under the Sevenin
                                                Family Trust


Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>




                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller

<PAGE>









                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>






                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the "Company") and the Stephen and
Andrea Turner Family Trust, a shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement, Prime agrees to purchase from Seller, as of the Effective Time, 7,920
authorized  and issued  shares of the  Company's  $0.01 par value  common  stock
presently  owned by Seller and  evidenced by stock  certificate  number C-28 and
C-38  (collectively,  the "Capital  Stock").  The purchase price for the Capital
Stock shall be $131,004.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578


Seller:                         Stephen and Andrea Turner Family Trust
                                250 Stonewall Road
                                Berkeley, California   94705

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]


<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President



Seller:                                  /s/ Stephen G. Turner, M.D.
                                         /s/ Andrea J. Turner
                                        Printed Name:   Stephen G. Turner, M.D.,
                                                Trustee under the Stephen and
                                                Andrea Turner Family Trust
                                                Andrea J. Turner, Trustee


Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>




                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller

<PAGE>









                            STOCK PURCHASE AGREEMENT

                                      Among

                          PRIME/BDR ACQUISITION, L.L.C.


                           --------------------------


                                       and

                           Horizon Vision Center, Inc.

                              --------------------


                             Dated September 1, 1999


<PAGE>






                            STOCK PURCHASE AGREEMENT

     This Stock  Purchase  Agreement  (this  "Agreement")  is entered into to be
effective  as of  September  1, 1999 (the  "Effective  Time"),  among  Prime/BDR
Acquisition,  L.L.C., a Delaware limited  liability company  ("Prime"),  Horizon
Vision Center,  Inc., a Nevada  corporation  (the  "Company") and Medical Vision
Technology  Profit,  Sharing Plan for the benefit of Stephen  Wilmarth,  M.D., a
shareholder of the Company ("Seller").

         The parties hereto agree as follows:

                                    ARTICLE I

                         Agreement of Purchase and Sale

     1.1 Agreement.  Upon the basis of the representations  and warranties,  for
the  consideration,  and subject to the terms and  conditions  set forth in this
Agreement,  Prime agrees to purchase  from  Seller,  as of the  Effective  Time,
13,876  authorized  and issued  shares of the  Company's  $0.01 par value common
stock presently owned by Seller and evidenced by stock  certificate  number C-31
(collectively,  the "Capital  Stock").  The purchase price for the Capital Stock
shall be $157,393.00 (the "Purchase Price").

         1.2 Closing.  The closing of the  transactions  contemplated by Section
1.1 (the  "Closing")  shall take place at the  offices of Akin,  Gump,  Strauss,
Hauer & Feld, L.L.P., 1900 Frost Bank Plaza, 816 Congress Avenue,  Austin, Texas
78701, or at such other location as the parties may agree. The date on which the
Closing occurs is hereinafter referred to as the "Closing Date."

     1.3 Payment of Purchase  Price.  The Purchase Price is to be paid to Seller
at the Closing by check or money order.

                                   ARTICLE II

                     Representations and Warranties of Prime

         Prime  represents  and  warrants to Seller  that each of the  following
matters  is true  and  correct  in all  respects  as of the  Closing  (with  the
understanding  that Seller is relying  materially  on such  representations  and
warranties in entering into and performing  this Agreement and each of the other
contracts, documents, instruments or agreements to be entered into in connection
with or as  contemplated  by  this  Agreement,  all of  which  are  collectively
referred to as the "Transaction Documents"):

         2.1 Due Organization and Principal Executive Office. Prime is a limited
liability company duly organized,  validly existing,  and in good standing under
the laws of the State of Delaware and has full corporate  power and authority to
carry on its business as now conducted and as proposed to be conducted. Prime is
controlled by Prime Medical Operating,  Inc., a Delaware  corporation  ("PMOI"),
and PMOI is a direct  or  indirect  wholly  owned  subsidiary  of PMSI.  Prime's
principal  executive  offices  are  located at 1301  Capital  of Texas  Highway,
Austin, Texas 78746.

         2.2 Due Authorization.  Prime has full corporate power and authority to
enter into and perform this Agreement and each Transaction  Document required to
be executed by Prime in connection herewith. This Agreement and each Transaction
Document  required  herein to be  executed  by Prime have been duly and  validly
authorized, executed and delivered by Prime and constitute the valid and binding
obligations of Prime  enforceable  against it in accordance with its terms.  The
execution,  delivery,  and  performance of this  Agreement and each  Transaction
Document  required  herein to be  executed  by Prime  will not (a)  violate  any
federal, state, county, or local law, rule, or regulation applicable to Prime or
its properties, (b) violate or conflict with, or permit the cancellation of, any
agreement to which Prime is a party or by which it or its  properties are bound,
(c) permit the  acceleration  of the  maturity  of any  indebtedness  of, or any
indebtedness  secured by the property of, Prime or (d) violate or conflict  with
any provision of the organizational  documents of Prime. No action,  consent, or
approval of, or filing with, any federal,  state,  county, or local governmental
authority is required by Prime in  connection  with the  execution,  delivery or
performance of this Agreement or any Transaction Document.

         2.3  Brokers  and  Finders.  Prime  has not  engaged,  or  caused to be
incurred any liability to, any finder, broker, or sales agent (and has not paid,
and will not pay, any finder's fee or similar fee or  commission  to any person)
in connection with the execution,  delivery, or performance of this Agreement or
the transactions contemplated hereby.

         2.4  Claims  and  Proceedings.  Prime  is not a  party  to any  claims,
actions, suits, proceedings,  or investigations,  at law or in equity, before or
by any court,  municipal or other governmental  department,  commission,  board,
agency, or instrumentality  which seeks to restrain or prohibit the carrying out
of the transactions  contemplated by this Agreement or to challenge the validity
of such  transactions or any part thereof or seeking damages on account thereof;
and, to the  knowledge of Prime,  no such claim,  action,  suit,  proceeding  or
investigation is threatened.

                                   ARTICLE III

                    Representations and Warranties of Seller

         Seller  hereby  represents  and  warrants  to  Prime  that  each of the
following  matters is true and correct in all  respects  as of the Closing  Date
(with  the  understanding   that  Prime  is  relying  materially  on  each  such
representation  and warranty in entering into and  performing  this  Agreement),
which  representations  and  warranties  shall  also  be  deemed  made as of the
Effective Time and which shall survive the Closing:

         3.1 Due  Authorization.  Seller has full power and  authority  to enter
into and perform this  Agreement and each  Transaction  Document  required to be
executed  by  Seller  in  connection  herewith.  This  Agreement  and each  such
Transaction  Document has been duly and validly executed and delivered by Seller
and constitutes a valid and binding  obligation of Seller,  enforceable  against
Seller in accordance with its terms. The execution, delivery, and performance of
this Agreement,  and each Transaction Document required herein to be executed by
Seller do not (a) violate any federal,  state,  county,  or local law,  rule, or
regulation  applicable to Seller or the Capital  Stock,  (b) violate or conflict
with, or permit the  cancellation  of, any agreement to which Seller is a party,
or by which Seller or the Capital  Stock is bound,  or result in the creation of
any lien,  security interest,  charge, or encumbrance upon the Capital Stock, or
(c) permit the  acceleration of the maturity of any  indebtedness of Seller.  No
action,  consent,  waiver or approval  of, or filing with,  any federal,  state,
county or local governmental  authority is required by Seller in connection with
the execution,  delivery,  or performance of this Agreement (or any  Transaction
Document).

     3.2 Stock Transferred.  The Capital Stock transferred by Seller to Prime at
the Closing will be free of any liens, claims or encumbrances whatsoever.

         3.3 Ownership.  Immediately  following the Closing Date,  except as set
forth on  Schedule  3.3,  Seller  does not own (i) any shares of equity or other
voting securities of the Company, (ii) any securities of the Company convertible
into or  exchangeable  for shares of equity or other  voting  securities  of the
Company,  (iii) any options or other rights to acquire from the Company,  or any
obligation of the Company to issue or sell, equity or other voting securities of
the Company,  or securities of the Company  convertible into or exchangeable for
such equity or voting securities, and (iv) any equity equivalents,  interests in
the ownership or earnings, rights to participate in the election of directors or
other similar rights of or with respect to the Company.

         3.4 Claims and Proceedings.  No inquiry, action, or proceeding has been
asserted,  instituted,  or threatened against Seller to restrain or prohibit the
carrying out of the transactions  contemplated by this Agreement or to challenge
the  validity of such  transactions  or any part  thereof or seeking  damages on
account thereof.

                                   ARTICLE IV

                                    Covenants

     4.1  Cooperation  Relating to Financial  Statements.  The Company agrees to
cooperate  with Prime in the  preparation  of any  financial  statements  of the
Company which Prime or its  affiliates  may be required by any applicable law to
prepare.

     4.2  Capital  Contributions.  The  parties  acknowledge  and agree that any
capital  contributions  to the Company after the date of this Agreement shall be
governed by the organizational documents of the Company.

         4.3  Issuance of Stock.  The Company  agrees that it will not after the
Closing,  without the prior written consent of Prime in each instance, issue any
equity securities or other ownership interests in the Company, or any securities
or rights  convertible into, or exchangeable or exercisable for, any such equity
securities or other ownership interests in the Company.

         4.4 Distribution of Working Capital. In accordance with the resolutions
adopted by Horizon on August 10, 1999, the parties agree that all cash in excess
of the minimum  amount of Working  Capital  (as  hereinafter  defined)  required
pursuant to Section 5.2(h) shall be  distributed  within thirty (30) days of the
Closing (as  dividends)  to the  shareholders  of Horizon  existing on August 1,
1999.

                                    ARTICLE V

                              Conditions to Closing

     5.1 Prime's Closing Obligations. At the Closing, Prime shall (each of which
is a condition to the obligations of Seller to close):

                  (a)      deliver the Purchase Price to Seller;

                    (b) execute and deliver each of the Transaction Documents to
               which it is a party; and

                    (c)  deliver  such  good  standing   certificates,   officer
               certificates,  and similar  documents and certificates as counsel
               for Seller may reasonably require.

     5.2 Seller's and the Company's Closing Obligations.  At the Closing, Seller
and the Company agree that (each of which is a condition to the  obligations  of
Prime to close):

     (a) each of them will execute and deliver each of the Transaction Documents
to which it is a party;

                  (b) a  sufficient  number of the  shareholders  of the Company
shall have entered into stock purchase  agreements (the "Related  Acquisitions")
for the sale of all or part of their capital  stock of the Company,  pursuant to
which,  immediately  after the Closing of this  transaction,  Prime will own not
less than sixty percent (60%) of the Company's  issued and  outstanding  capital
stock,  considering all classes of stock, and assuming the conversion,  exercise
or exchange of all rights,  options,  or other  securities  convertible  into or
exercisable or exchangeable for any shares of the Company's capital stock;

                  (c)  each  of  the   shareholders  of  the  Company   existing
immediately prior to the Closing (including Seller) that is a physician or other
licensed  medical  professional  shall have  executed and  delivered to Prime an
Exclusive Use Agreement in substantially the form attached hereto as Exhibit A;

                  (d) Seller, and each of the other Company shareholders selling
Company stock to Prime in a Related  Acquisition  (the "Selling  Shareholders"),
who will  remain a  shareholder  of the  Company  after the  Closing  shall have
executed  and  delivered  to Prime an  Assignment  and  Security  Agreement,  in
substantially  the form  attached  hereto as  Exhibit  B,  granting  a  security
interest  in such  shareholder's  remaining  stock in the  Company to secure the
performance by such shareholder  under any agreement it has with Prime or any of
Prime's affiliates;

                  (e) the  Company  shall  have  adopted,  after  obtaining  all
necessary   approvals  and  consents,   the  Amended  and  Restated  Bylaws,  in
substantially  the form  attached  hereto as  Exhibit  C,  which  shall  contain
provisions  governing  its  board  of  directors  that are  consistent  with the
provisions of Section 9.4 of this Agreement, including, without limitation, that
the number of directors  serving on its board of directors of the Company  shall
be five (5);

                  (f) at the Closing,  the  Company's  board of directors  shall
consist of three (3)  individuals  designated  by Prime and  listed on  Schedule
5.2(f)  hereto,  and  two  (2)  individuals  designated  by a  majority  of  the
shareholders of the Company  immediately prior to Closing and listed on Schedule
5.2(f) hereto;

                  (g) the Company shall have delivered to Prime true and correct
copies of  resignations,  effective  as of the  Closing  Date,  from each of the
persons holding the offices set forth on Schedule 5.2(g) hereto, and the persons
listed on Schedule  5.2(g)  hereto  shall have been  elected or appointed to the
office set forth opposite their name;

                  (h) As of the Closing Date,  the amount of Working  Capital of
the Company shall be at least $100,000 (for purposes of this Agreement, "Working
Capital"  means the  difference  between  (i) cash,  cash  equivalents,  prepaid
expenses and Accounts Receivable less than sixty (60) days old and (ii) accounts
payable and other  liabilities  and  payment  obligations  due in the  following
twelve (12) months, all as determined in accordance with GAAP); and

                  (i) each of them,  and each  Selling  Shareholder,  shall have
delivered such good standing  certificates,  officer  certificates,  and similar
documents and certificates as counsel for Prime may have reasonably requested.

                                   ARTICLE VI

                            Indemnification of Prime

         6.1      Indemnification of Prime.

                  (a) The Company  agrees to indemnify and hold harmless  Prime,
each subsidiary and/or affiliate of Prime (including,  without limitation,  PMOI
and PMSI) and each  shareholder,  member,  partner  (or other  owner),  officer,
director, agent, employee,  representative and affiliate of any of the foregoing
(collectively,  the "Prime  Indemnified  Parties")  from and against any and all
damages, losses, claims, liabilities, demands, charges, suits, penalties, costs,
and expenses (including court costs and attorneys' fees and expenses incurred in
investigating  and preparing for any  litigation or  proceeding)  (collectively,
"Indemnified  Costs") in connection  with the  commencement  or assertion of any
action,  proceeding,  demand,  or  claim  by  a  third  party  (collectively,  a
"third-party  action") which any of the Prime  Indemnified  Parties may sustain,
arising  out of any  breach or  default  by Seller or the  Company of any of the
representations, warranties, covenants or agreements contained in this Agreement
or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(a)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $25,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

                  (b) Seller  agrees to indemnify  and hold  harmless each Prime
Indemnified  Party from and against any and all Indemnified  Costs in connection
with the  commencement or assertion of any  third-party  action which any of the
Prime Indemnified  Parties may sustain,  arising out of any breach or default by
Seller  of any of  its  representations,  warranties,  covenants  or  agreements
contained in this Agreement or any Transaction Document.

                  Notwithstanding  the  foregoing,  no Prime  Indemnified  Party
shall be entitled  to assert any claim for  indemnification  under this  Section
6.1(b)  unless  and  until  such time as all  claims  of all  Prime  Indemnified
Parties,  taken  together,  exceed $10,000 in the  aggregate,  at which time all
claims of such Prime  Indemnified  Parties  may be asserted  individually  or in
combination (beginning with the first dollar).

         6.2 Defense of Third-Party Claims. A Prime Indemnified Party shall give
prompt written notice to the Company and, if applicable, Seller (collectively in
instances  involving the Seller, the "indemnifying  party"), of the commencement
or  assertion  of any  third  party  action  in  respect  of  which  such  Prime
Indemnified Party shall seek indemnification hereunder. Any failure to so notify
the  indemnifying  party  shall not  relieve  the  indemnifying  party  from any
liability  that it may have to such Prime  Indemnified  Party under this ARTICLE
unless the failure to give such notice  materially and adversely  prejudices the
indemnifying  party.  The  indemnifying  party  shall  have the  right to assume
control of the defense of,  settle,  or  otherwise  dispose of such  third-party
action on such terms as it deems appropriate; provided, however, that:

     (a) The Prime Indemnified Party shall be entitled,  at his, her, or its own
expense, to participate in the defense of such third-party action;

                  (b) The  indemnifying  party  shall  obtain the prior  written
approval  of  the  Prime  Indemnified   Party,   which  approval  shall  not  be
unreasonably   withheld,   before   entering  into  or  making  any  settlement,
compromise,  admission,  or  acknowledgment  of the validity of such third-party
action or any  liability  in respect  thereof if,  pursuant to or as a result of
such settlement,  compromise, admission, or acknowledgment,  injunctive or other
equitable relief would be imposed against the Prime Indemnified Party;

                  (c) The  indemnifying  party shall not consent to the entry of
any  judgment  or  enter  into  any  settlement  that  does  not  include  as an
unconditional  term  thereof the  execution  and  delivery of a release from all
liability in respect of such  third-party  action by each  claimant or plaintiff
to, and in favor of, each Prime Indemnified Party; and

                  (d) The  indemnifying  party  shall not be entitled to control
(but shall be entitled to participate at its own expense in the defense of), and
the Prime  Indemnified  Party shall be entitled to have sole control  over,  the
defense  or  settlement,   compromise,   admission,  or  acknowledgment  of  any
third-party  action  as to which the  indemnifying  party  fails to  assume  the
defense within thirty (30) days; provided,  however,  that the Prime Indemnified
Party shall make no settlement,  compromise,  admission, or acknowledgment which
would give rise to liability (other than liability to Prime Indemnified  Parties
under this Agreement) on the part of the indemnifying  party,  without the prior
written consent of the indemnifying party.

                  (e) The indemnifying  party shall make payments of all amounts
required to be made pursuant to the  foregoing  provisions of this ARTICLE to or
for the account of the Prime  Indemnified  Party from time to time promptly upon
receipt of bills or invoices relating thereto or when otherwise due and payable,
provided that the Prime Indemnified Party has agreed in writing to reimburse the
indemnifying party for the full amount of such payments if the Prime Indemnified
Party is ultimately determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

         6.3 Limitation of Seller's Liability.  Notwithstanding  anything to the
contrary  contained in this ARTICLE,  the  aggregate  liability of Seller to all
Prime  Indemnified  Parties for all Indemnified  Amounts payable by Seller under
Section  6.1(b) shall be limited to the  aggregate  Purchase  Price  received by
Seller under this Agreement,  plus the greater of (a) the value of all remaining
equity interests which Seller holds in the Company at the time of Closing or (b)
the value of all remaining equity interests which Seller holds in the Company at
the time an Indemnified Amount is required to be paid.

                                   ARTICLE VII

                    Indemnification of Seller and the Company

         7.1  Indemnification  of  Seller  and  the  Company.  Prime  agrees  to
indemnify  and hold harmless  Seller and the Company,  and each of the Company's
directors,  officers,   shareholders,   agents,  employees  and  representatives
(collectively,  the "Seller Indemnified Parties"),  from and against any and all
Indemnified  Costs in connection with the commencement or assertion of any third
party action which any of the Seller  Indemnified  Parties may sustain,  arising
out of any breach or default by Prime of any of the representations, warranties,
covenants or agreements contained in this Agreement or any Transaction Document.

                  Notwithstanding  the foregoing,  no Seller  Indemnified  Party
shall be entitled to assert any claim for indemnification under this Section 7.1
unless  and until  such time as all  claims of such  Seller  Indemnified  Party,
individually  and not in  combination  with other  Seller  Indemnified  Parties,
exceed  $25,000  in the  aggregate,  at which  time all  claims  of such  Seller
Indemnified Party may be asserted (beginning with the first dollar).

         7.2 Defense of Third-Party  Claims.  A Seller  Indemnified  Party shall
give prompt  written  notice to Prime of the  commencement  or  assertion of any
third party action in respect of which such Seller  Indemnified Party shall seek
indemnification  hereunder.  Any  failure so to notify  Prime  shall not relieve
Prime from any liability that it may have to such Seller Indemnified Party under
this ARTICLE  unless the failure to give such notice  materially  and  adversely
prejudices  Prime.  Prime shall have the right to assume  control of the defense
of, settle, or otherwise dispose of such third-party  action on such terms as it
deems appropriate; provided, however, that:

     (a) The  Seller  Indemnified  Party  shall be  entitled,  at his or its own
expense, to participate in the defense of such third-party action;

                  (b) Prime  shall  obtain  the prior  written  approval  of the
Seller  Indemnified  Party,  which approval shall not be unreasonably  withheld,
before  entering  into or  making  any  settlement,  compromise,  admission,  or
acknowledgment  of the validity of such  third-party  action or any liability in
respect thereof if, pursuant to or as a result of such  settlement,  compromise,
admission,  or  acknowledgment,  injunctive or other  equitable  relief would be
imposed against the Seller Indemnified Party;

                  (c) Prime  shall not  consent to the entry of any  judgment or
enter into any settlement that does not include as an unconditional term thereof
the  execution  and delivery of a release from all  liability in respect of such
third-party  action by each  claimant  or  plaintiff  to, and in favor of,  each
Seller Indemnified Party; and

                  (d) Prime  shall not be  entitled  to  control  (but  shall be
entitled to  participate  at its own expense in the defense  of), and the Seller
Indemnified  Party shall be entitled to have sole control  over,  the defense or
settlement,  compromise,  admission, or acknowledgment of any third-party action
as to which Prime fails to assume the defense within thirty (30) days; provided,
however, that the Seller Indemnified Party shall make no settlement, compromise,
admission,  or  acknowledgment  which would give rise to  liability  (other than
liability to Seller  Indemnified  Parties  under this  Agreement) on the part of
Prime without the prior written consent of Prime.

                  (e) Prime shall make  payments  of all amounts  required to be
made pursuant to the foregoing  provisions of this ARTICLE to or for the account
of the Seller Indemnified Party from time to time promptly upon receipt of bills
or invoices  relating  thereto or when otherwise due and payable,  provided that
the Seller  Indemnified  Party has agreed in writing to reimburse  Prime for the
full  amount of such  payments  if the Seller  Indemnified  Party is  ultimately
determined not to be entitled to such indemnification.

                  (f) The parties hereto shall extend reasonable  cooperation in
connection with the defense of any  third-party  action pursuant to this ARTICLE
and, in  connection  therewith,  shall furnish such  records,  information,  and
testimony and attend such conferences,  discovery proceedings, hearings, trials,
and appeals as may be reasonably requested.

                                  ARTICLE VIII

                              Restrictive Covenants

         8.1 Confidentiality  Agreement.  Seller and the Company each agree that
it has been and may  continue to be,  through its  relationship  with Prime,  be
exposed to confidential  information and trade secrets pertaining to, or arising
from, the business of Prime and/or each of Prime's present or future  affiliates
(which includes, without limitation, Prime, PMOI, PMSI and each of their present
or future affiliates)  (individually and collectively,  "Discloser"),  that such
information  and trade secrets are unique and valuable and that Discloser  would
suffer  irreparable injury if this information or trade secrets were divulged to
those in  competition  with  Discloser.  Therefore,  Seller and the Company each
agree to keep in strict secrecy and confidence, both during and after the period
during  which Prime owns any interest in the  Company,  any and all  information
concerning Discloser which Seller or the Company acquires, or to which Seller or
the Company has access through its  relationship  with  Discloser,  that has not
been publicly disclosed by Discloser or that is not a matter of common knowledge
by  Discloser's  competitors  (collectively,   "Proprietary  Information").  The
Proprietary  Information covered by this Agreement shall include,  but shall not
be limited to,  information  relating to any  inventions,  processes,  software,
formulae, plans, devices,  compilations of information,  technical data, mailing
lists, management strategies,  business distribution methods, names of suppliers
(of both goods and  services)  and  customers,  names of employees  and terms of
employment,  arrangements entered into with suppliers and customers,  including,
but not limited to, proposed  expansion plans of Discloser,  marketing and other
business and pricing strategies, and trade secrets of Discloser.

         Except with prior written approval of Discloser, neither Seller nor the
Company will: (i) directly or indirectly,  disclose any Proprietary  Information
to any person except  authorized  personnel of Discloser or (ii) use Proprietary
Information  in any  way.  Within  forty-eight  (48)  hours of the time at which
Prime's and its  affiliates'  aggregate  voting equity  interests in the Company
constitute  less than  fifty  percent  (50%) of the  outstanding  voting  equity
interests of the Company, whether the disposition resulting in such ownership is
voluntary or  involuntary,  each of Seller and the Company will deliver to Prime
(without   retaining   copies   thereof)   all   documents,   records  or  other
memorializations including copies of documents and any notes which Seller or the
Company  has  prepared,  that  contain  Proprietary  Information  or  relate  to
Discloser's business, all other tangible Proprietary  Information in Seller's or
the Company's  possession or control, and all of Discloser's credit cards, keys,
equipment,  vehicles,  supplies and other  materials  that are in  possession or
under Seller's or the Company's control.

         8.2  Agreement by Seller and the  Company.  Seller and the Company each
hereby  agrees  that,  until the fifth (5th)  anniversary  of the Closing  Date,
neither Seller nor the Company will directly or  indirectly,  either through any
kind of  ownership  (other  than  ownership  of  securities  of a publicly  held
corporation  of  which it owns  less  than  five  percent  (5%) of any  class of
outstanding  securities),  or  as a  principal,  shareholder,  agent,  employer,
employee, advisor, consultant, co-partner or in any individual or representative
capacity  whatever,  either for its own  benefit or for the benefit of any other
person, corporation or other entity, without the prior written consent of Prime,
commit any of the following acts,  which acts shall be considered  violations of
this covenant not to compete:

                  (a) Except  through  the  Company,  engage in or  provide  any
services  that are provided by the  Company,  directly or  indirectly,  anywhere
within a two  hundred  (200) mile  radius of any center or  facility at any time
operated by the Company or any of the Company's affiliates,  including,  without
limitation,  any  services  related to, (i) the  operating  of laser  refractive
surgical centers, (ii) the manufacture, maintenance, refurbishing, repair, sale,
or leasing of any  equipment  related to or necessary for the operating of laser
refractive  surgical  centers,  or  (iii)  providing  any  management  services,
training or consulting  services  related to any of the activities  described in
(i) or (ii);

                  (b) Directly or indirectly request or advise any person, firm,
physician,  corporation  or other  entity  having a business  relationship  with
Prime,  or any affiliate or related entity of Prime,  to withdraw,  curtail,  or
cancel its business with Prime or such affiliate or related entity; or

                  (c) Directly or indirectly  hire any employee of Prime, or any
affiliate  or related  entity of Prime,  or induce or attempt to  influence  any
employee of Prime or any such  affiliate or related  entity to terminate  his or
her employment with Prime or any such affiliate or related entity.

         8.3 Restrictions Reasonable.  Seller and the Company have each reviewed
and carefully  considered  the  provisions of this ARTICLE and,  having done so,
agrees that the  restrictions  applicable to it as set forth herein (a) are fair
and  reasonable  with respect to time,  geographic  area and scope,  (b) are not
unduly  burdensome to it, and (c) are reasonably  required for the protection of
the  interests of the other parties  hereto for whose benefit such  restrictions
were agreed upon.

         8.4  Remedies.  Seller and the Company  each agrees that a violation on
its part of any  applicable  covenant  contained  in this ARTICLE will cause the
other  parties  hereto for whose  benefit  such  restrictions  were  agreed upon
irreparable  damage for which remedies at law may be insufficient,  and for that
reason,  Seller and the  Company  each agrees  that the other  parties  shall be
entitled  as a  matter  of  right  to  equitable  remedies,  including  specific
performance and injunctive relief,  therefor.  The right to specific performance
and  injunctive  relief shall be  cumulative  and in addition to whatever  other
remedies,  at law or in  equity,  that the other  parties  may have,  including,
specifically, recovery of additional damages.

                                   ARTICLE IX

                             Post Closing Agreements

         9.1 Right of Set Off.  Seller and the  Company  each  agrees that Prime
shall have rights of offset  against  distributions  to Seller in respect of any
ownership interest it may have in the Company immediately  following the Closing
or at any  time  thereafter  arising,  for  any and all  debts,  obligations  or
liabilities that Seller may have to Prime,  including,  without limitation,  any
liability arising out of or relating to any obligation arising under Seller's or
the Company's  indemnity  obligations  under this  Agreement or any  Transaction
Document.  Seller hereby authorizes the Company, and appoints the Company as its
attorney  in fact,  to pay such  offset  amounts  to Prime and to take all other
actions  necessary  in  connection  with such  payment.  The  Company  agrees to
promptly remit any and all such offset amounts to Prime upon request.

         9.2      Special Options to Sell or Acquire Remaining Capital Stock.

                  (a)  Prohibition  on Sale.  Notwithstanding  anything  in this
Agreement to the  contrary,  Seller  agrees that it will not  transfer,  assign,
pledge,  hypothecate,  or in any way alienate any of its shares of capital stock
of the Company, or any interest therein,  whether voluntarily or by operation of
law, or by gift or otherwise,  except in accordance  with the provisions of this
Section or Section  9.3,  or except  pursuant  to that  certain  Assignment  and
Security  Agreement by and between  Prime or one of its  affiliates  and Seller,
dated as of the date of this Agreement (the "Security Agreement"). Any purported
transfer  in  violation  of this  Section  or  Section  9.3  shall  be void  and
ineffectual,  and shall not  operate to  transfer  any  interest or title to the
purported transferee. Seller agrees that the Company may, and the Company agrees
to, issue  stop-transfer  orders,  or take any other necessary action, to ensure
that the  foregoing  provisions  of this  Section and Section 9.3 are given full
effect.

                  (b) Option to Sell.  Upon (i) the death,  retirement  (only if
Seller  is a  physician  and only as  defined  below),  bankruptcy,  insolvency,
disability  (only if  Seller  is a  physician  and  only as  defined  below)  or
incompetency of Seller, (ii) any other involuntary transfer of any capital stock
of the  Company  now or  hereafter  owned by  Seller,  or any  interest  therein
(including, without limitation,  transfers of interests upon divorce or death of
a spouse of Seller,  but excluding  any  transfers  governed by Section 9.3), or
(iii) the performance by Seller,  during any one-month  period,  of greater than
thirty  (30%) of his or her  professional  medical  activities  outside of a two
hundred (200) mile radius of the center or facility primarily utilized by Seller
prior to the  date of this  Agreement;  the  Seller's  executor,  administrator,
trustee,  custodian,  receiver or other legal or  personal  representative  (the
"Representative"), or Seller, in the case of retirement or departure, shall give
written notice of that fact to the Company. In such event, the Representative or
Seller shall have a period of sixty (60) days (the "Put  Period")  following the
date of such death, retirement, bankruptcy, insolvency, disability, incompetency
or shift in the geographical  location of Seller's practice, as the case may be,
within  which time it may  require  that the  Company  purchase  (subject to the
remaining  provisions of this  subsection) all of Seller's  capital stock of the
Company,  upon the terms and conditions  hereinafter set forth, by giving notice
of such election in writing to Company. The Company may, in its sole discretion,
offer all or a portion of such capital stock to its shareholders,  on a pro rata
basis in relation to each shareholder's percentage ownership of the Company, but
any agreement by the  shareholders  to purchase all or a portion of such capital
stock shall not limit the Company's obligation to purchase within the time frame
set forth in this Section.  If the Company has offered all of such capital stock
to its shareholders,  and the shareholders have not committed to purchase all of
such capital stock within five (5) days from the date of offer, then the Company
may, in its sole  discretion,  offer all or a portion of the  remaining  capital
stock to Prime, in which event Prime must  participate in such purchase upon the
same terms and conditions as the Company.  For purposes of this  Agreement,  (x)
"disability"  shall  apply  only if Seller  is a  physician  and shall  mean any
condition  which in the  reasonable  judgment of a majority  of the  managers of
Prime,  would impair Seller's  ability to materially  perform his or her routine
duties for a period of six (6) months or more, (y) "retirement" shall apply only
if Seller is a physician and shall mean the cessation of the routine practice of
medicine  (provided that any physician who transfers his or her entire  practice
to  a  licensed  medical   professional   meeting  the  Company's  then  current
credentialing  program  shall not be deemed to have retired for purposes of this
subsection),  and (z) "incompetent"  shall mean a state of legal incompetence as
declared by a court of valid jurisdiction.

                  (c) Option to Buy. In the event that the option  described  in
Section 9(b) arises and the  Representative or Seller, as the case may be, fails
to make the  election  described  in Section  9(b) within the Put Period,  Prime
shall at all times  thereafter have the option to purchase all or any portion of
Seller's capital stock of the Company, upon the terms and conditions hereinafter
set forth,  by giving written  notice of such election in writing to Seller.  In
addition, Prime may, in its sole discretion, transfer its purchase right granted
under this subsection (or stock acquired pursuant to an exercise of its purchase
right  granted  under  this  subsection)  to  Horizon  or any  of the  physician
shareholders of the Company.

                  (d) Purchase Price.  The purchase price to be paid pursuant to
this Section shall be paid in immediately  available funds at the closing of the
transfer  of capital  stock  pursuant  to this  Section.  If the  parties do not
otherwise  agree  within  thirty  (30)  days of the day on which  the  option to
purchase or sell hereunder is exercised,  then Prime shall,  at its own expense,
select an appraiser to value the capital stock being  transferred.  If Seller or
Representative  does not agree with the value  determined  by the  appraiser  of
Prime,  Seller  or  Representative  may,  at its  own  expense,  select  its own
appraiser to value the capital stock being  transferred.  If the two  appraisers
cannot  agree on the  value of the  capital  stock  being  transferred,  the two
appraisers  shall mutually  select a third  appraiser to value the capital stock
being transferred, and any valuation determined by such third appraiser shall be
final, binding and conclusive. The cost of any third appraiser shall be borne by
Seller.

                  (e) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth  day)  following  the delivery of notice under either  Section 9(b) or
Section 9(c). At such closing,  Seller shall execute all documents and take such
other  actions as may be  reasonably  necessary to deliver to Prime such capital
stock,  and any  certificates  representing  same,  free and clear of all liens,
claims,  encumbrances or restrictions of any kind or nature  whatsoever,  except
those imposed under the Security Agreement.

9.3      Right of First Refusal.

                  (a) If there is no  option  to sell or buy  outstanding  under
Section 9.2 (except in  connection  with a sale by a physician  of all of his or
her practice upon  retirement),  and Seller intends to voluntarily  transfer any
portion of its capital  stock of the Company to any person or entity  other than
Prime,  then Seller shall give written notice to Prime stating (i) the intention
to transfer  such capital  stock,  (ii) the number of shares to be  transferred,
(iii) the name, business and residence address of the proposed transferee,  (iv)
the  nature  and  amount of the  consideration,  and (v) the other  terms of the
proposed sale.

                  (b) Prime shall have, and may exercise  within sixty (60) days
after receipt of the notice of intent to transfer,  an option to purchase all or
any portion of the  capital  stock of the  Company  owned by Seller,  at the per
share price and upon the other terms stated in the notice of intent to transfer.
Prime may elect to exercise its option under this Section by  delivering  notice
thereof to Seller.  If Prime  elects not to purchase  all or any portion of such
capital  stock prior to the  expiration  of said sixty (60) day  period,  Seller
shall have thirty (30) days to complete  the sale and purchase  contemplated  in
the notice of intent to  transfer,  and after such thirty  (30) day period,  the
provisions  of this  Section  shall  apply fully to any such  capital  stock not
transferred.  The  purchase  price  pursuant  to this  Section  shall be paid in
immediately  available  funds at the  closing of the  transfer  pursuant to this
Section.

                  (c)  Seller and Prime  acknowledge  and agree that it would be
impractical to exercise an option to purchase  arising  pursuant to this Section
whenever the proposed consideration to be received by Seller is other than cash,
cash  equivalents  or an  obligation  to  pay  cash  by a  person  whose  credit
worthiness  and  financial  status  is  such  that  performance  of the  payment
obligation  would be reasonably  assured.  Therefore,  the parties agree that no
transfer  shall be permitted and no option shall arise  pursuant to this Section
whenever the consideration to be received from the proposed  transferee is other
than cash,  cash  equivalents  or an  obligation  to pay cash by a person  whose
credit  worthiness and financial  status is such that performance of the payment
obligation would be reasonably assured.

                  (d) The  closing of any  purchase  and sale of  capital  stock
pursuant to this Section  shall take place at the  principal  office of Prime or
such other place  designated  by Prime and Seller,  on the  thirtieth day (or if
such  thirtieth  day is not a business  day, the next business day following the
thirtieth day) following the delivery of notice of Prime's  election to purchase
pursuant to Section 9(b).  At such  closing,  Seller shall execute all documents
and take such other actions as may be  reasonably  necessary to deliver to Prime
such capital stock,  and any certificates  representing  same, free and clear of
all  liens,  claims,   encumbrances  or  restrictions  of  any  kind  or  nature
whatsoever, except those imposed under the Security Agreement.

         9.4 Voting  Agreement.  Each of the parties  hereto agrees that it will
vote all of the shares of capital  stock of the Company owned by it, at any time
after the  execution of this  Agreement,  in  accordance  with the terms of this
Section  9.4.  Any  additional  shares of voting  capital  stock or other voting
securities  of the  Company,  or the  voting  rights  related  thereto,  whether
presently  existing  or  created  in the  future,  that may be owned,  held,  or
subsequently  acquired  in any  manner,  legally or  beneficially,  directly  or
indirectly,  of  record  or  otherwise,  by the  parties  at any time  after the
execution of this Agreement,  whether issued incident to any stock split,  stock
dividend, increase in capitalization,  recapitalization,  merger, consolidation,
share exchange,  reorganization, or other transaction, shall be shall be subject
to the terms of this  Section  (all such  stock  presently  held or  controlled,
together with such additional stock, the "Subject Shares").  At each election of
directors  of the  Company,  the parties and any  transferee  or assignee of any
Subject Shares from the parties (the "Transferee") shall, in accordance with the
procedure  set forth below,  vote the Subject  Shares as necessary to elect five
(5) persons, designated in accordance with the procedures below, to the board of
directors of the company.  Three (3) of the  directors  (the "Prime  Designees")
shall be designated in writing by Prime or its Transferee. The remaining two (2)
directors (the "Other  Stockholder  Designees")  shall be jointly  designated in
writing by stockholders of the corporation other than Prime (or any entity other
than the Company that is controlled by, controlling or under common control with
Prime) (the "Other  Stockholders")  holding a majority of the  aggregate  voting
equity stock held by all Other Stockholders.  For purposes of this Section,  the
Prime Designees and the Other  Stockholder  Designees are sometimes  referred to
individually  as  a  "Designated   Director"  and  collectively  as  "Designated
Directors." During the term of this Agreement,  the parties shall, in accordance
with the procedure set forth below,  (i) vote their Subject Shares and use their
best  efforts in any event to ensure  that the number of  directors  which shall
constitute  the entire board of  directors  of the Company  shall remain at five
(5),  (ii) vote their  Subject  Shares in favor of the  removal of a  Designated
Director if Prime or a majority in interest of the Other Stockholders (whichever
designated the  respective  director)  instruct in writing that such  Designated
Director shall be removed from office and (iii) upon any removal of a Designated
Director  pursuant  to (ii)  above,  vote their  Subject  Shares in favor of the
election of a replacement  director designated in writing by Prime or a majority
in interest  of the Other  Stockholders  (whichever  designated  the  respective
director).  None of the parties to this Agreement shall approve or authorize the
removal of any Designated Director unless Prime or a majority in interest of the
Other  Stockholders  (whichever  designated the respective  director) shall have
authorized in writing such Designated Director's removal. To the extent that any
party or parties entitled to designate a director  pursuant to this Section fail
to designate a replacement  Designated Director under this Section, the position
vacated shall remain vacant until such time as a new director is designated  and
elected pursuant to the terms hereof.

         Upon delivery of any written notice designating or removing one or more
directors pursuant to this Section,  the parties hereto and any Transferee shall
either (i) sign a written consent, prepared for execution by the stockholders of
the Company in accordance  with the Bylaws of the Company,  which consent elects
or removes  the  director(s)  designated  in writing to be elected or removed in
accordance  with this  Section  or (ii) at any  annual or  special  shareholders
meeting at which director(s) are to be elected or removed,  vote in favor of the
election or removal of the  director(s)  designated  in writing to be elected or
removed in  accordance  with this  Section.  If  necessary  to fix the number of
directors  constituting  the entire  board of directors at five (5), the parties
hereto shall either (i) sign such written consents prepared for execution by the
shareholders of the Company in accordance with the Bylaws of the Company or (ii)
at any annual or special  shareholders  meeting,  vote in favor of such motions;
which  consents or motions  propose to fix the number of directors  constituting
the entire board of directors at five (5).

         Each of the parties  hereto  agrees to take such  actions,  and execute
such  documents,  agreements  or  instruments  (including,  without  limitation,
consents  amending the articles or bylaws of the Company),  as may be necessary,
due to changes in the law or  otherwise,  to ensure that the  provisions of this
Section 9.4 are given full effect.

         9.5 Limited Waiver of Indemnity.  Each party to this  Agreement  waives
any right to  indemnification  by, and  agrees  not to seek any  indemnification
from, the Company for any act,  omission or other matter (whether  arising under
the Company's  organizational  documents or otherwise),  to the extent that such
party is required by this Agreement to indemnify another party to this Agreement
in respect of such act, omission or other matter.

         9.6 Post-Closing Capital  Contributions.  All parties to this Agreement
acknowledge  and agree that no shareholder  of the Company,  or any other party,
has any obligation  existing on the Closing Date to make a capital  contribution
to the Company.

         9.7 Stock  Legend.  On and  after  the  Closing,  each  certificate  or
document  representing Seller's ownership of any of the Company's capital stock,
and each certificate or document that may be issued and delivered by the Company
upon transfer of such certificate, shall contain a legend conspicuously noted in
substantially the following form:

                           THE SHARES  REPRESENTED BY THIS  CERTIFICATE HAVE NOT
                  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AND THEY MAY
                  NOT BE SOLD OR  TRANSFERRED  EXCEPT  PURSUANT TO AN  EXEMPTION
                  FROM,  OR  OTHERWISE  IN A  TRANSACTION  NOT  SUBJECT  TO, THE
                  REGISTRATION REQUIREMENTS OF SUCH ACT.

                           IN  ADDITION,  SHARES  MAY  BE  TRANSFERRED  ONLY  IN
                  COMPLIANCE  WITH  CERTAIN  CONDITIONS  SPECIFIED  IN A CERTAIN
                  STOCK PURCHASE  AGREEMENT  DATED  EFFECTIVE AS OF SEPTEMBER 1,
                  1999, A COMPLETE  AND CORRECT  COPY OF WHICH IS AVAILABLE  FOR
                  INSPECTION AT THE PRINCIPAL  OFFICE OF THE COMPANY AND WILL BE
                  FURNISHED  TO THE  HOLDER  HEREOF  UPON  WRITTEN  REQUEST  AND
                  WITHOUT CHARGE.

                                    ARTICLE X

                                  Miscellaneous

         10.1 Collateral  Agreements,  Amendments,  and Waivers.  This Agreement
(together with the documents  delivered  pursuant  hereto)  supersedes all prior
documents,  understandings,  and agreements,  oral or written,  relating to this
transaction  and  constitutes  the entire  understanding  among the parties with
respect to the subject  matter  hereof.  Any  modification  or amendment  to, or
waiver of, any provision of this Agreement (or any document  delivered  pursuant
to this Agreement unless otherwise  expressly provided therein) may be made only
by an instrument in writing executed by each party thereto.

         10.2  Successors and Assigns.  No party's  rights or obligations  under
this Agreement may be assigned  without the prior written consent of all parties
hereto, except that Prime may assign its rights and obligations hereunder to any
entity,  more than 50% of the voting equity  ownership  interests of which is at
the time owned, directly or indirectly,  by PMSI. Any assignment in violation of
the foregoing shall be null and void. Subject to the preceding sentences of this
Section,  the  provisions of this Agreement  (and,  unless  otherwise  expressly
provided therein, of any document delivered pursuant to this Agreement) shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, legal representatives, successors, and assigns.

         10.3  Expenses.   Except  as  set  forth  in  the  following  sentence,
regardless of whether the transactions contemplated hereby are consummated, each
party  hereto  shall  pay  all of  its  costs  and  expenses  incurred  by it in
connection  with this  Agreement,  including the fees and  disbursements  of its
legal counsel and accountants.

         10.4  Severability.  If any  provision of this  Agreement is held to be
illegal,  invalid, or unenforceable under present or future laws, such provision
shall be fully severable,  this Agreement shall be construed as if such illegal,
invalid,  or  unenforceable  provision  had  never  comprised  a  part  of  this
Agreement,  and the remaining  provisions of this Agreement shall remain in full
force  and  effect  and  shall  not be  affected  by the  illegal,  invalid,  or
unenforceable provision or by its severance from this Agreement.

         10.5 Waiver. No failure or delay on the part of any party in exercising
any right, power, or privilege hereunder or under any of the documents delivered
in  connection  with this  Agreement  shall  operate as a waiver of such  right,
power, or privilege; nor shall any single or partial exercise of any such right,
power,  or  privilege  preclude  any other or  future  exercise  thereof  or the
exercise of any other right, power or privilege.

         10.6 Notices.  Any notices required or permitted to be given under this
Agreement (and, unless otherwise expressly provided therein,  under any document
delivered  pursuant  to this  Agreement)  shall be given in writing and shall be
deemed  received  (a) when  delivered  personally  or by courier  service to the
relevant  party at its address as set forth below or (b) if sent by mail, on the
third day following the date when deposited in the United States mail, certified
or  registered  mail,  postage  prepaid,  to the  relevant  party at its address
indicated below:

Prime:                          1301 Capital of Texas Highway
                                Suite C-300
                                Austin, Texas  78746
                                Attention:  President

with a copy to:                 Mr. Timothy L. LaFrey
                                Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                816 Congress Avenue, Suite 1900
                                Austin, Texas  78701

Company:                        Horizon Vision Centers, Inc.
                                14895 East 14th Street, Suite 400
                                San Leandro, California   94578


Seller:                         Medical Vision Technology Profit Sharing Plan
                                FBO Stephen Wilmarth, M.D.
                                9824 Carlton Court
                                Granite Bay, California   95746

         Each party may change  its  address  for  purposes  of this  Section by
proper notice to the other parties.

         10.7 Survival of Representations, Warranties, and Covenants. Regardless
of any  investigation at any time made by or on behalf of any party hereto or of
any  information  any  party  may  have  in  respect  thereof,   all  covenants,
agreements, representations, and warranties made hereunder or pursuant hereto or
in  connection  with the  transactions  contemplated  hereby  shall  survive the
Closing.

         10.8 Further Assurances.  At, and from time to time after, the Closing,
each  party  shall,  at the  request  of  another  party,  but  without  further
consideration,  execute  and  deliver  such  other  instruments  of  conveyance,
assignment, assumption, transfer and delivery and take such other action as such
party may  reasonably  request  in order  more  effectively  to  consummate  the
transactions contemplated hereby.

         10.9  Construction,  Knowledge and Materiality.  This Agreement and any
documents or instruments  delivered  pursuant  hereto or in connection  herewith
shall be construed  without regard to the identity of the person who drafted the
various  provisions of the same.  Each and every provision of this Agreement and
such other  documents  and  instruments  shall be construed as though all of the
parties  participated  equally in the  drafting of the same.  Consequently,  the
parties  acknowledge and agree that any rule of construction  that a document is
to be construed  against the drafting  party shall not be  applicable  either to
this  Agreement or such other  documents and  instruments.  For purposes of this
Agreement,  whenever  there are references to "material" or  "materially,"  such
terms shall be deemed to mean an economic impact exceeding  $10,000 with respect
to the fact or matter being referred to or described.  As used herein,  "day" or
"days" refers to calendar days unless otherwise specified in each instance. When
the term  "knowledge" is used in this Agreement in reference to Prime,  it shall
mean such  items as are  within  the actual  knowledge  of Ken  Shifrin,  Cheryl
Williams, Mark Rosenberg and Dr. Jenkins.

     10.10  Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of Texas.

         10.11 Arbitration.  Any controversy  between the parties regarding this
Agreement  and any claims  arising out of this  Agreement or its breach shall be
submitted to binding  arbitration by either party.  The arbitration  proceedings
shall be conducted by a single arbitrator pursuant to the Commercial Arbitration
Rules  of  the  American  Arbitration  Association.  The  arbitration  shall  be
conducted  in  Dallas,  Texas and the  arbitrator  shall have the right to award
actual  damages  and  attorney  fees and costs,  but shall not have the right to
award punitive, exemplary or consequential damages against either party.

10.12 Counterparts. This Agreement may be executed in several counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same  instrument.  Any party  hereto may execute  this  Agreement by
signing any one counterpart.

                            [Signature page follows]


<PAGE>
                                SIGNATURE PAGE TO

                            STOCK PURCHASE AGREEMENT

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement as of the day and year first above written.

Prime:                                      Prime/BDR Acquisition, L.L.C.

                                            By: /s/ Cheryl Williams

                                            Printed Name: Cheryl Williams

                                            Title: Vice President



Seller:                                  /s/ Stephen Wilmarth, M.D.
                                        Printed Name:   Stephen Wilmarth, M.D.,
                                                Trustee under the Medical Vision
                                                Technology Profit Sharing Plan,
                                                for the benefit of Stephen
                                                Wilmarth, M.D.


Company:                            Horizon Vision Center, Inc.

                                            By: /s/ David P. Bates III

                                            Printed Name: David P. Bates III

                                            Title: President



<PAGE>




                                TABLE OF EXHIBITS

EXHIBIT A:                 Form of Exclusive Use Agreement

EXHIBIT B:                 Form of Assignment and Security Agreement

EXHIBIT C:                 Form of Amended and Restated Bylaws of Seller





                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein,  jointly and severally,  as "Secured  Party") and David P. Bates III and
Jane A. Bates (collectively referred to as the "Debtor").
                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         David P. Bates III and Jane A. Bates
                                  1320 Canyon Side Avenue
                                  San Ramon, California   94583

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.

DEBTOR:

                                          /s/ David Bates

                                          Printed Name:  David Bates

                                          /s/ Jane A. Bates

                                          Printed Name:  Jane A. Bates


SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein,  jointly and  severally,  as "Secured  Party") and John Robert  Griffin,
M.D., Family Revocable Trust dated February 8, 1991 (the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         John Robert Griffin, M.D., Trustee under the
                                  Family Revocable Trust dated February 8, 1991
                                  4913 Puma Way
                                  Carmichael, California   95608

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.


DEBTOR:                            /s/ John Robert Griffin, M.D., Trustee

                                   Printed Name: John Robert Griffin, M.D.,
                                   Trustee under the John Robert Griffin, M.D.
                                   Family Revocable Trust dated February 8, 1991


SECURED PARTY:                     Prime Medical Operating, Inc.

                                   By: /s/ Cheryl Williams

                                   Name: Cheryl Williams

                                   Title: Vice President


                                   Prime/BDR Acquisition, L.L.C.

                                   By: /s/ Cheryl Williams

                                   Name: Cheryl Williams

                                   Title: Vice President

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein,  jointly and severally,  as "Secured  Party") and Christian K. Kim, M.D.
(the "Debtor").
                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         Christian K. Kim, M.D.
                                  40 Presidio Drive
                                  Novato, California   94949

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                   /s/ Christian K. Kim, M.D.

                                          Printed Name: Christian K. Kim, M.D.


SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Secretary and Manager

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein,  jointly and severally,  as "Secured  Party") and Mark R. Mandel,  M.D.,
Trustee under the Trust Agreement dated April 12, 1989 (the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         Mark R. Mandel, M.D., Trustee under Trust
                                  Agreement dated April 12, 1989
                                  680 Brewer Road
                                  Hillsborough, California   94010

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                   /s/ Mark R. Mandel, M.D.

                                          Printed Name: Mark R. Mandel, M.D.,
                                          under Trustee Agreement dated
                                          April 12, 1989

SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein,  jointly  and  severally,  as  "Secured  Party")  and D.  Brent Reed and
Carellyn S. Reed (collectively and individually referred to as the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         D. Brent Reed and Carellyn S. Reed
                                  157 Cascade Falls Drive
                                  Folsom, California   95630

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                   /s/ D. Brent Reed

                                          Printed Name: D. Brent Reed

                                          /s/ Carellyn S. Reed

                                          Printed Name: Carellyn S. Reed

SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein, jointly and severally,  as "Secured Party") and Bradley J. Sandler, M.D.
(the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         Bradley J. Sandler, M.D.
                                  403 Calle De Caballo
                                  Suisun City, California   94585-1501

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                   /s/ Bradley J. Sandler, M.D.

                                          Printed Name: Bradley J. Sandler, M.D.


SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Secretary and Manager

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein, jointly and severally,  as "Secured Party") and the Severin Family Trust
(the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         The Severin Family Trust
                                  Sanford L. Severin, Trustee
                                  1040 McCauley Road
                                  Danville, California   94526

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                   /s/ Sanford L. Severin, Trustee

                                          Printed Name: Sanford L. Severin,
                                          Trustee under the Severin Family Trust

SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein,  jointly and severally,  as "Secured  Party") and the Stephen and Andrea
Turner Family Trust (the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         Stephen and Andrea Turner Family Trust
                                  250 Stonewall Road
                                  Berkeley, California   94705

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                   /s/ Stephen G. Turner, M.D.

                                          Printed Name: Stephen G. Turner, M.D.
                                          Trustee under the Stephen and Andrea
                                          Turner Family Trust

                                          /s/ Andrea J. Turner

                                          Printed Name: Andrea J. Turner
                                          Trustee under the Stephen and Andrea
                                          Turner Family Trust


SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein,  jointly and severally,  as "Secured  Party") and Stephen Wilmarth, M.D.
(the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         Medical Vision Technology Profit Sharing Plan
                                  FBO Stephen Wilmarth, M.D.
                                  9824 Carlton Court
                                  Granite Bay, California   95746

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                   /s/ Stephen Wilmarth, M.D.

                                          Printed Name: Stephen Wilmarth, M.D.


SECURED PARTY:                            Prime Medical Operating, Inc.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President


                                          Prime/BDR Acquisition, L.L.C.

                                          By: /s/ Cheryl Williams

                                          Name: Cheryl Williams

                                          Title: Vice President

<PAGE>



                        ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating, Inc., a Delaware corporation ("PMOI"), Prime/BDR Acquisition, L.L.C.,
a Delaware limited  liability  company ("Prime") (PMOI and Prime are referred to
herein, jointly and severally, as "Secured Party") and Medical Vision Technology
Profit Sharing Plan for the benefit of Stephen Wilmarth, M.D. (the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Stock  Purchase   Agreement  dated  as  of  September  1,  1999  (the  "Purchase
Agreement"),  pursuant to which  Secured  Party  purchased  from Debtor  certain
shares of the $0.01 par value  common  stock of Horizon  Vision  Center,  Inc, a
Nevada corporation ("Horizon").

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or hereafter have to Secured Party, including, without limitation, any indemnity
obligations arising under the Purchase Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured  Party's  purchase  of  Debtor's  shares of Horizon  under the  Purchase
Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

                  (a)  Shares  of  Horizon.  From  and  after  the  date of this
Agreement,  (i) all shares of the common  stock of Horizon  owned or acquired in
any manner by Debtor or Secured Party,  (collectively,  the "Shares"),  (ii) any
replacements,  substitutions,  or exchanges of the certificates representing the
Shares, and (iii) any and all options,  rescission rights,  registration rights,
conversion rights, subscription rights, contractual or quasi-contractual rights,
warrants,  redemption rights,  redemption proceeds, calls, preemptive rights and
all other rights and benefits pertaining to the Shares;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Debtor now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Debtor is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive or shall  receive  in  connection  with any of the
Collateral  described in this Section 1.1: (i) any stock certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets, combination of shares, stock split,
reverse  stock split or  spin-off;  (ii) any option,  warrant,  subscription  or
right,  whether as an addition to or in  substitution  of any of the  Collateral
described in this Section 1.1; (iii) any dividends or  distributions of any kind
whatsoever,  whether  distributable in cash,  stock or other property;  (iv) any
interest,  premium or principal  payments;  and (v) any conversion or redemption
proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a), (b), or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any  indemnity  obligations)  under and pursuant to the Purchase  Agreement,
this Agreement and/or any other contract or agreement  between Secured Party and
Debtor or any affiliate of Debtor (collectively, "Other Agreements"; and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor and/or any affiliate of Debtor to Secured Party of any kind or character,
now existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed,  contingent,  liquidated,  unliquidated,  joint,  several  or  joint  and
several,  arising from,  connected with, or related to the Purchase Agreement or
any Other Agreement, or any other document, agreement, or instrument executed in
connection  either of them,  (ii) all accrued but unpaid  interest on any of the
indebtedness  described in (i) above, (iii) all obligations of Debtor and/or any
affiliate  of  Debtor  to  Secured  Party  under  any  documents  or  agreements
evidencing,  securing,  governing  and/or  pertaining  to all or any part of the
indebtedness  described  in (i) and (ii)  above,  (iv) all  costs  and  expenses
incurred by Secured Party in connection  with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party to  Debtor,  or  expended  by Secured  Party for the  account of Debtor or
otherwise owing by Debtor to Secured Party, in respect of the  Obligations,  and
all other sums  expended or advanced  by Secured  Party  pursuant to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3  No  Agreements.  The  Shares  are  not  subject  to any  right  of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is solvent;
(ii) the fair saleable  value of Debtor's  assets exceeds  Debtor's  liabilities
(both fixed and contingent);  (iii) Debtor has sufficient capital to satisfy all
of Debtor's  obligations  as they  become due;  (iv) no  receiver,  trustee,  or
custodian has been appointed for, or taken  possession of, all or  substantially
all of the assets of Debtor,  either in a  proceeding  brought by Debtor or in a
proceeding  brought against Debtor;  (v) Debtor is not the subject of a petition
for relief under the United  States  Bankruptcy  Code or any similar  federal or
state insolvency law, including without limitation a petition filed by Debtor or
a petition filed by a third party seeking relief against Debtor; and (vi) Debtor
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of  creditor  relief,  within  the  two-year  period  immediately
following the date of this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform its obligations  under the Purchase  Agreement and each Other Agreement.
No further  consent or approval is  required as a condition  to the  validity of
this  Agreement,  the Purchase  Agreement or any Other  Agreement.  Debtor is in
compliance with all applicable laws, ordinances,  statutes, orders, regulations,
judgments, writs, or decrees of any governmental entity to which it is subject.

         3.3 Binding Agreement.  This Agreement, the Purchase Agreement and each
Other Agreement  constitute valid and legally binding  obligations of Debtor, in
accordance  with  their  terms,  subject  to  (a)  the  applicable   bankruptcy,
insolvency,  reorganization,  moratorium,  and similar laws affecting creditors'
rights  generally  and  (b)  restrictions  imposed  by any  court  of  competent
jurisdiction on the enforcement of non-competition and exclusive use restrictive
covenants imposed under the Purchase Agreement or any Other Agreement.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's ability to perform its obligations  under this Agreement,  the Purchase
Agreement or any Other Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement, the Purchase Agreement
or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
shares  of  any  class  of  securities  of  such  issuer,  (ii)  any  instrument
convertible  voluntarily  by  the  holder  thereof  or  automatically  upon  the
occurrence or  non-occurrence  of any event or condition  into, or  exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.  Notwithstanding  the  foregoing  or any  other  provision  of  this
Agreement to the contrary,  Debtor (i) shall comply with his  obligations  under
the  Purchase  Agreement  and each Other  Document,  and (ii) may consent to any
issuance of shares of Horizon if such  issuance has been  approved by a majority
of the Board of Directors of Horizon.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding  the  Shares  unless  consented  to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Debtor  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Debtor's
financial condition or on Debtor's ability to perform the Obligations.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid under the Purchase Agreement (including,  without limitation, the indemnity
provisions  contained  therein),  or any other  amount  which  Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
(15) calendar days after such amount is due;

     (b) The failure of Debtor to pay any  Obligation  within (15) calendar days
after such amount is due; and

                  (c)  Debtor's  breach of a covenant in this  Agreement  or any
other  failure to perform  its  obligations  under this  Agreement  or any Other
Agreement.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in an intrastate  offering  under Section  3(a)(11) of the Securities
Act of 1933,  and no sale so made in good faith by Secured Party shall be deemed
to be not "commercially reasonable" because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the Purchase Agreement or any Other
Agreement;  (d) then,  to or among the amounts of fees,  interest and  principal
then owing and unpaid in respect of the Obligations, in such priority as Secured
Party may determine in its  discretion;  and (e) the remainder of such proceeds,
if any,  shall be paid to Debtor.  If such  proceeds  shall be  insufficient  to
discharge the entire  Obligations,  Secured Party shall have any other available
legal recourse  against Debtor under,  or for the  performance  of, the Purchase
Agreement and any Other  Agreement  between  Debtor and Secured  Party,  for the
deficiency,  together with interest  thereon at the maximum rate permitted under
applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of the Purchase Agreement or Other
Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY,  PROTECT,  DEFEND AND HOLD HARMLESS  SECURED PARTY, ITS
OFFICERS, DIRECTORS, REPRESENTATIVES, AGENTS, EMPLOYEES, LENDERS, SUCCESSORS AND
ASSIGNS,  FROM AND AGAINST ALL  LIABILITIES,  CLAIMS,  DAMAGES,  LOSSES,  FINES,
PENALTIES,  CAUSES OF ACTIONS,  SUITS,  JUDGMENTS AND EXPENSES  (INCLUDING COURT
COSTS,  ATTORNEY'S  FEES  AND  COST OF  INVESTIGATION)  OF ANY  NATURE,  KIND OR
DESCRIPTION  OF ANY PERSON OR ENTITY,  DIRECTLY OR  INDIRECTLY,  ARISING OUT OF,
CAUSED BY OR  RESULTING  FROM (IN WHOLE OR IN PART),  ANY  UNINTENTIONAL  ACT OR
OMISSION (OR  INTENTIONAL  ACT OR OMISSION SO LONG AS SUCH ACT OR OMISSION  DOES
NOT  CONSTITUTE  NEGLIGENCE)  OF SECURED  PARTY (OR  ANYONE  ACTING ON BEHALF OF
SECURED PARTY) IN CONNECTION WITH THE COLLATERAL.  THE FOREGOING INDEMNITY SHALL
SURVIVE THE EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed  and  observed by Debtor  under the Purchase  Agreement or Other
Agreement,  or in respect of the Collateral  (subject to any applicable  default
cure  period),  Secured  Party (a) may but shall  not be  obligated  to take any
action Secured Party deems  necessary or desirable to prevent or remedy any such
default by Debtor or otherwise to protect the Security  Interest,  and (b) shall
have the absolute and immediate  right to take  possession of the  Collateral or
any  part  thereof  (to  the  extent  Secured  Party  has not  previously  taken
possession)  to such  extent  and as often  as the  Secured  Party,  in its sole
discretion, deems necessary or desirable in order to prevent or to cure any such
default by Debtor,  or  otherwise  to protect the  security  of this  Agreement.
Secured Party may advance or expend such sums of money for the account of Debtor
as Secured Party in its sole discretion deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become involved by reason of or arising out of the Purchase Agreement, any Other
Agreement or the  Collateral,  shall be a part of the  Obligations  and shall be
paid by Debtor to Secured Party, upon demand, and shall bear interest until paid
at the maximum  rate of interest  permitted  by  applicable  law,  from the date
incurred by Secured Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

         8.14 Relationship Among Secured Party.  Either or both of Secured Party
are  entitled  to enforce  any and all rights  granted to Secured  Party in this
Agreement,  and to take any other  action  allowed to be taken by Secured  Party
under this  Agreement.  Neither  Secured  Party is under any  obligation  to act
jointly or in concert with the other Secured Party  pursuant to this  Agreement.
Any action  required  to be taken by Debtor,  or notice  required to be given by
Debtor, shall be taken or given with respect to both of Secured Party.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:  1301 Capital of Texas Hwy., Suite C-300
                                  Austin, Travis County, Texas 78746
                                  Attn: President

                  with copy to:   Timothy L. LaFrey, Esq.
                                  Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1900 Frost Bank Plaza
                                  816 Congress Avenue
                                  Austin, Texas 78701

                  Debtor:         Stephen Wilmarth, M.D.
                                  9824 Carlton Court
                                  Granite Bay, California   95746

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Debtor may not assign this  Agreement or any of its rights
or obligations  hereunder  without the express prior written  consent of Secured
Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT.  THIS AGREEMENT AND THE PURCHASE AGREEMENT REPRESENT
THE FINAL AGREEMENT  BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE
ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                            [Signature page follows]


<PAGE>


S-1



                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1st day of September, 1999.



DEBTOR:                                 /s/ Stephen Wilmarth, M.D.

                                        Printed Name: Stephen Wilmarth, M.D.,
                                        Trustee under Medical Vision Technology
                                        Profit Sharing Plan for the benefit of
                                        Stephen Wilmarth, M.D.

SECURED PARTY:                          Prime Medical Operating, Inc.

                                        By: /s/ Cheryl Williams

                                        Name: Cheryl Williams

                                        Title: Vice President


                                        Prime/BDR Acquisition, L.L.C.

                                        By: /s/ Cheryl Williams

                                        Name: Cheryl Williams

                                        Title: Vice President

<PAGE>





                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>

                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:

                                   Signature: /s/ J. Robert Griffin, M.D.

                                   Printed Name: J. Robert Griffin

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David P. Bates III

                                   Printed Name: David P. Bates III

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name: Cheryl Williams

                                   Title: Vice President

<PAGE>


                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>
                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:
                                   Signature: /s/ Christian S. Kim, M.D.

                                   Printed Name: Christian S. Kim, M.D.

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David Bates

                                   Printed Name: David Bates

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name:Cheryl Williams

                                   Title: Vice President


<PAGE>

                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>


                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:
                                   Signature: /s/ Mark R. Mandel, M.D.

                                   Printed Name: Mark R. Mandel, M.D.

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David Bates

                                   Printed Name: David Bates

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name:Cheryl Williams

                                   Title: Vice President
<PAGE>


                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>
                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:

                                   Signature: /s/ D. Brent Reed, M.D.

                                   Printed Name: D. Brent Reed, M.D.

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David Bates

                                   Printed Name: David Bates

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name: Cheryl Williams

                                   Title: Vice President


<PAGE>

                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>
                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:

                                   Signature: /s/ Bradley J. Sandler, M.D.

                                   Printed Name: Bradley J. Sandler, M.D.

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David Bates

                                   Printed Name: David Bates

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name: Cheryl Williams

                                   Title: Vice President


<PAGE>

                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>

                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:

                                   Signature: /s/ Sanford L. Severin, M.D.

                                   Printed Name: Sanford L. Severin, M.D.

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David Bates

                                   Printed Name: David Bates

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name: Cheryl Williams

                                   Title: Vice President
<PAGE>


                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>
                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:

                                   Signature: /s/ Stephen G. Turner, M.D.

                                   Printed Name: Stephen G. Turner, M.D.

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David Bates

                                   Printed Name: David Bates

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name: Cheryl Williams

                                   Title: Vice President


<PAGE>


                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>


S-1



                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:
                                   Signature: /s/ Stephen Wilmarth, M.D.

                                   Printed Name: Stephen Wilmarth

                                   Title:
                                   (if  signing  in  a representative capacity)



HORIZON:                           Horizon Vision Centers, Inc.

                                   Signature: /s/ David P. Bates

                                   Printed Name: David P. Bates

                                   Title: President



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name: Cheryl Williams

                                   Title: Vice President


<PAGE>


                             EXCLUSIVE USE AGREEMENT

         This Exclusive Use Agreement  (this  "Agreement") is entered into as of
the 1st day of  September,  1999  (the  "Effective  Date"),  by the  undersigned
shareholder  (the  "Equity  Holder") of Horizon  Vision  Center,  Inc., a Nevada
corporation  ("Horizon")  for the benefit of Horizon and Prime/BDR  Acquisition,
L.L.C., a Delaware limited  liability company ("Prime") and the parent companies
and affiliates of each of Horizon and Prime.

                                    RECITALS:

         WHEREAS, the Equity Holder is a shareholder of Horizon.

         WHEREAS,  the Equity  Holder is a physician or other  licensed  medical
professional.

         WHEREAS,   concurrently   with  the  execution  and  delivery  of  this
Agreement,  Prime and Horizon  are  consummating  that  certain  Stock  Purchase
Agreement (the "Stock Purchase Agreement"), dated September 1, 1999.

         WHEREAS,  in order to  induce  Horizon  and  Prime  to  consummate  the
transactions contemplated by the Stock Purchase Agreement, the Equity Holder has
agreed,  for a period of five (5)  years,  to  perform  all  Refractive  Surgery
Services (as defined  herein)  exclusively  at the  facilities of, and using the
equipment of, Horizon.

         THEREFORE, the parties hereto agree as follows:

                                   AGREEMENTS:

         1. Exclusive Use. Except as expressly  otherwise provided below, during
the term of this  Agreement,  the Equity Holder hereby agrees that,  without the
prior written consent of both Horizon and Prime, the Equity Holder will perform,
and will direct all other medically  trained or licensed  medical  professionals
under the  direction  or control of Equity  Holder to  perform,  all  Refractive
Surgery Services only at the facilities of, and using the equipment of, Horizon.
For purposes of this Agreement,  "Refractive Surgery Services" shall include all
refractive  surgery  modalities,  now or at any  time  during  the  term of this
Agreement performed,  offered or made available,  including, without limitation,
implantable   contact   lenses,   instromal   corneal  rings,   laser  in  situs
keratomileusis   photorefractive  keratectomy,   radial  keratotomy,   automated
lemellar   keratoplasty,   astigmatic  keratotomy  and  similar  or  replacement
procedures.

         Provided, however, that nothing in this Agreement shall be construed to
require Equity Holder to perform  Refractive  Surgery Services at the facilities
of, or use the equipment of, Horizon, if in Equity Holder's professional medical
judgment,  such use would be detrimental to Equity Holder's  patients.  Provided
further,  that this Agreement shall not apply to any Refractive Surgery Services
to be paid for, or reimbursed  by,  Medicare,  Medicaid,  Champus,  or any other
state or  federal  health  care  program,  or in any  other  instance  where the
operation of this Agreement would constitute a violation of applicable law.

         2.  Access.  Horizon  and Prime each agree that during the term of this
Agreement,  and for as long Equity  Holder  continues to meet the  credentialing
requirements of Horizon's  credentialing program as in effect from time to time,
Equity Holder shall be given access to Horizon's facilities, equipment and staff
in the same manner  such access has  generally  been  provided to Equity  Holder
prior to the date of this Agreement.

         3. Other Agreements.  Horizon and Prime each agree that during the term
of this  Agreement  and  for as long as  Equity  Holder  continues  to meet  the
credentialing  requirements of Horizon's credentialing program as in effect from
time to time,  Equity  Holder's  compensation  arrangement  will be  modified to
incorporate the terms of any  compensation  arrangement with any other physician
utilizing the  facilities,  equipment and staff,  to the extent such other terms
are substantially more favorable than the terms enjoyed by Equity Holder.

         4.  Allocation  of  Procedures.  Horizon  and  Prime  each  agree  that
inquiries  generated  by  Horizon  and not by a  particular  physician  shall be
distributed  among the  physician  shareholders  of  Horizon  (including  Equity
Holder) in a manner  consistent with the allocation  methods employed by Horizon
prior to the date of this  Agreement,  limited,  however,  in instances  where a
physician is not available to perform the procedure.

     5. Term. The term of this  Agreement  shall begin on the Effective Date and
shall continue for a period of five (5) years thereafter.

         6. Breach.  The Equity  Holder  agrees that a violation of any covenant
contained  in  Section 1 will  irreparably  damage  Horizon  and Prime for which
remedies at law may be  insufficient,  and for that  reason,  the Equity  Holder
further  agrees  that  Horizon  and Prime  shall each be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that Horizon and Prime may have, including, specifically, recovery of additional
damages.

         7.       Miscellaneous.

               (a) Amendments. This Agreement may be modified or amended only by
          an instrument in writing executed by each of the parties hereto.

               (b) Headings.  The headings  contained in this  Agreement are for
          reference purposes only and shall not affect in any way the meaning or
          interpretation of this Agreement.

                  (c) Counterparts. This Agreement may be executed in any number
         of  counterparts,  each of which  shall be deemed an  original,  but in
         making proof hereof it shall not be necessary to produce or account for
         more than one such counterpart.

               (d) Governing Law. This Agreement shall be construed and enforced
          in accordance  with the internal  laws of the State of Texas,  and not
          the conflicts of law provisions thereof.

               (e) Parties Bound.  This  Agreement  shall be binding upon and be
          enforceable  against the Equity Holder.  This Agreement shall inure to
          the  benefit  of  Horizon,  Prime  and  their  respective  successors,
          representatives and assigns.

               (f) Assignment.  This Agreement and the rights granted  hereunder
          may not be assigned by Equity  Holder  without the written  consent of
          both Horizon and Prime.

                  (g)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  parties  participated  equally in the
         drafting of this Agreement.  Consequently,  the parties acknowledge and
         agree that any rule of construction  that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (h)  Severability.  This Agreement is intended to be performed
         in accordance with, and only to the extent permitted by, all applicable
         laws,  ordinances,  rules and  regulations.  If any  provision  of this
         Agreement,  or the application  thereof to any person or  circumstance,
         shall,  for any reason and to any extent,  be invalid or  unenforceable
         but the extent of the invalidity or  unenforceability  does not destroy
         the basis of the bargain between the parties as contained  herein,  the
         remainder of this  Agreement and the  application  of such provision to
         other  persons or  circumstances  shall not be  effected  thereby,  but
         rather shall be enforced to the fullest extent permitted by law.

                                                    [Signature page to follow]
                                                     -------------------------


<PAGE>


S-1



                                SIGNATURE PAGE TO

                             EXCLUSIVE USE AGREEMENT

         EXECUTED to be effective as of the date first above written.

EQUITY HOLDER:
                                   Signature: /s/ Robert J. Hardy

                                   Printed Name: Robert J. Hardy

                                   Title:
                                   (if  signing  in  a representative capacity)



PRIME:                             Prime/BDR Acquisition, L.L.C.

                                   Signature: /s/ Cheryl Williams

                                   Printed Name: Cheryl Williams

                                   Title: Vice President




                           AMENDED AND RESTATED BYLAWS

                               for the regulation

                                       of

                          HORIZON VISION CENTERS, INC.

              (a Nevada corporation incorporated January 30, 1996)

                       ARTICLE I - MEETING OF STOCKHOLDERS

         Section 1. ANNUAL  MEETINGS.  The annual meeting of the stockholders of
the corporation shall be held once each year at such place within or without the
State of Nevada as shall be  designated  by the Board of  Directors,  and if not
designated by the Board,  then as designated by the Chairman of the Board or the
President,  for the purpose of electing  directors of the  corporation  to serve
during the ensuing year and for the transaction of such other business as may be
properly  brought before the annual meeting.  The annual meeting of stockholders
shall be held during the fifth or sixth month  following  the  conclusion of the
corporation's  fiscal year on such date which is not a weekend or legal holiday,
and at such time, as shall be  designated by the Board of Directors,  and if not
designated by the Board,  then as designated by the Chairman of the Board or the
President, for the purpose.

         Section 2. SPECIAL  MEETINGS.  Special meetings of the stockholders may
be held at the principal office of the corporation,  within or without the State
of Nevada,  whenever  called by the Board of  Directors  by the  Chairman of the
Board,  or by  the  President  of the  corporation,  only  for  the  purpose  of
transacting  such  business as shall be  specified in the notice of such special
meeting which may provide,  however, for the transaction of other matters as may
be properly brought before the special meeting.

         Section 3. NOTICE OF ANNUAL OR SPECIAL MEETINGS. Written notice of each
annual or special meeting of stockholders  shall be given not less than ten (10)
nor more than sixty (60) days before the date of the meeting to each stockholder
entitled to vote  thereat.  Such notice shall state the place,  date and hour of
the meeting and (i) in the case of a special meeting,  the general nature of the
business to be transacted,  and no other business may be transacted,  or (ii) in
the case of the annual  meeting,  the  election  of  directors  and those  other
matters  which the Board,  at the time of the mailing of the notice,  intends to
present  for  action by the  stockholders,  but  subject  to the  provisions  of
applicable  law,  any proper  matter may be  presented  at the  meeting for such
action.  The notice of any meeting at which  directors  are to be elected  shall
include the names of nominees intended at the time of the notice to be presented
by management for election.

         Notice of a stockholders'  meeting shall be given either  personally or
by mail or by other means of written communication, addressed to the stockholder
at the address of such stockholder  appearing on the books of the corporation or
given by the stockholder to the corporation for the purpose of notice, or, if no
such address appears or is given, at the place where the principal office of the
corporation  is located,  either  within or without  the State of Nevada,  or by
publication at least once in a newspaper of general circulation in the county in
which the  principal  office is located.  Notice by mail shall be deemed to have
been given at the time a written notice is deposited in the United States mails,
postage prepaid.  Any other written notice shall be deemed to have been given at
the time it is personally delivered to the recipient or is delivered to a common
carrier for  transmission,  or  actually  transmitted  by the person  giving the
notice by electronic means, to the recipient.

         Section 4.  QUORUM AND  REQUIRED  APPROVALS.  A majority  of the shares
entitled to vote,  represented in person or by proxy,  shall constitute a quorum
at any meeting of stockholders.  If a quorum is present, the affirmative vote of
a majority of the shares  represented  and voting at the meeting  (which  shares
voting affirmatively also constitute at least a majority of the required quorum)
shall be the act of the  stockholders,  unless  the vote of a greater  number or
voting by classes is  required  by law or by the  Articles,  except as  provided
below in this  Section 4 and in Section 5 of this Article I. Except with respect
to the matters  listed  below  which  require  the  approval by at least  eighty
percent (80%) of the shares entitled to vote, the stockholders present at a duly
called or held  meeting at which a quorum is present may continue to do business
until  adjournment,  notwithstanding  the withdrawal of enough  stockholders  to
leave less than a quorum,  if any  action  taken  (other  than  adjournment)  is
approved by at least a majority of the shares required to constitute a quorum.

         Notwithstanding  the  foregoing,  the following  acts and  transactions
shall require the affirmative  vote of not less than eighty percent (80%) of the
shares entitled to vote, represented in person or by proxy:

(a) Unless pursuant to any contractual agreement to which the Company is a party
on the date of adoption of these  Amended and Restated  Bylaws,  any issuance of
any  capital  stock of the  corporation  (or  rights to acquire  capital  stock,
through conversion, exchange, exercise of options or otherwise);

(b) Unless pursuant to any contractual agreement to which the Company is a party
on the date of adoption of these Amended and Restated Bylaws,  any redemption of
any shares of capital stock of the corporation by the corporation;

(c)      The sale of all or substantially all of the assets of the corporation;

(d)      Any merger or reorganization of or by the corporation;

(e)      Liquidation or dissolution of the corporation; and

(f)      Any amendment to these Bylaws or to the Articles.

         Section 5.  ADJOURNED  MEETINGS AND NOTICE  THEREOF.  Any  stockholders
meeting,  whether or not a quorum is present, may be adjourned from time to time
by the vote of a  majority  of the  shares  represented  either  in person or by
proxy,  but in the absence of a quorum  (except as provided in Section 4 of this
Article) no other business may be transacted at such meeting.

         It shall not be  necessary  to give any notice of the time and place of
the adjourned meeting or of the business to be transacted thereat, other than by
announcement  at the  meeting  at which  such  adjournment  is taken;  provided,
however, when any stockholders meeting is adjourned for more than 45 days or, if
after adjournment a new record date is fixed for the adjourned  meeting,  notice
of the adjourned meeting shall be given as in the case of an original meeting.

         Section 6. VOTING.  The stockholders  entitled to notice of any meeting
or to vote at any such meeting shall be only persons in whose names shares stand
on the stock  records  of the  corporation  on the  record  date  determined  in
accordance with Section 7 of this Article.

         Elections  of  directors  and other  voting on  proposal  presented  to
stockholders  meeting  need  not be by  ballot  if  dispensed  by  the  meeting;
provided,  however,  that all elections for directors and other  proposals to be
voted upon must be by ballot upon demand made by any  stockholder at the meeting
and before the voting begins.

         In any  election  of  directors,  the  provisions  of  Article II shall
control.

         Except  as  otherwise  set  forth in  Article  II with  respect  to the
election of Directors, voting shall in all cases be subject to the provisions of
Section  78.355  of the  Nevada  General  Corporation  Law and to the  following
provisions:

         (a) Subject to clause (g), shares held by an  administrator,  executor,
guardian,  conservator or custodian may be voted by such holder either in person
or by proxy,  without a transfer  of such  shares into the  holder's  name;  and
shares standing in the name of a trustee may be voted by the trustee,  either in
person or by proxy, but no trustee shall be entitled to vote shares held by such
trustee without a transfer of such shares into the trustee's name.

         (b)  Shares  standing  in the name of a  receiver  may be voted by such
receiver,  and shares held by or under the control of a receiver may be voted by
such receiver without the transfer thereof into the receiver's name if authority
to do so is  contained  in the order of the  court by which  such  receiver  was
appointed.

         (c) Except where otherwise agreed in writing between the parties with a
copy furnished to the corporation,  a stockholder whose shares are pledged shall
be entitled to vote such shares until the shares have been  transferred into the
name of the pledgee,  and  thereafter  the pledgee shall be entitled to vote the
shares so transferred.

         (d)  Shares  standing  in the  name of a  minor  may be  voted  and the
corporation may treat all rights  incident  thereto as exercisable by the minor,
in person or by proxy,  whether or not the  corporation  has  notice,  actual or
constructive,  of the nonage, unless a guardian of the minor's property has been
appointed and written notice of such appointment given to the corporation.

         (e) Shares  standing  in the name of another  corporation,  domestic or
foreign,  may be voted by such officer,  agent or  proxyholder as the by-laws of
such other  corporation may prescribe or, in the absence of such  provision,  as
the Board of  Directors  of such  other  corporation  may  determine  or, in the
absence of such  determination,  by the chairman of the board,  president or any
vice president of such other  corporation,  or by any other person authorized to
do so by the  chairman of the board,  president  or any vice  president  of such
other corporation. Shares which are purported to be voted or any proxy purported
to be  executed  in the name of a  corporation  (whether or not any title of the
person signing is indicated) shall be presumed to be voted or the proxy executed
in accordance with the provisions of this clause, unless the contrary is shown.

          (f) Shares of the  corporation  owned by any  subsidiary  shall not be
     entitled to vote on any matter.

         (g) Shares held by the corporation in a fiduciary capacity,  and shares
of the issuing corporation held in a fiduciary capacity by any subsidiary, shall
not be entitled to vote on any matter,  except to the extent that the settlor or
beneficial  owner  possesses  and  exercises  a right  to  vote  or to give  the
corporation binding instructions as to how to vote such shares.

         (h) If shares  stand of  record  in the  names of two or more  persons,
whether fiduciaries, members of a partnership, joint tenants, tenants in common,
husband  and  wife  as  community  property,  tenants  by the  entirety,  voting
trustees,  persons  entitled to vote under a  stockholder  voting  agreement  or
otherwise,  or if two or more  persons  (including  proxyholders)  have the same
fiduciary  relationship  respecting the same shares, unless the Secretary of the
corporation is given written notice to the contrary and is furnished with a copy
of the instrument or order appointing them or creating the relationship  wherein
it is so provided,  their acts with  respect to voting shall have the  following
effect:

                  (i)      If only one votes, such acts binds all;

                    (ii) If more  than  one  vote,  the act of the  majority  so
               voting binds all;

                  (iii) If more than one vote,  but the vote is evenly  split on
any  particular  matter,  each  faction  may vote  the  securities  in  question
proportionately.

If the instrument so filed or the registration of the shares shows that any such
tenancy is held in unequal  interests,  a majority or even split for the purpose
of this Section shall be a majority or even split in interest.

         Section 7. RECORD  DATE.  The Board may fix, in advance,  a record date
for the  determination of the stockholders  entitled to notice of any meeting or
to vote or entitled to receive payment of any dividend or other distribution, or
any  allotment of rights,  or to exercise  rights in respect of any other lawful
action. The record date so fixed shall be not more than 60 days nor less than 10
days prior to the date of the  meeting  nor more than 60 days prior to any other
action.  When a record dates is so fixed,  only  stockholders  of record on that
date are  entitled  to notice of and to vote at the  meeting or to  receive  the
dividend, distribution, or allotment of rights, or to exercise of the rights, as
the case may be,  notwithstanding  any  transfer  of  shares on the books of the
corporation  after the record date. A  determination  of  stockholders of record
entitled to notice of or to vote at a meeting of stockholders shall apply to any
adjournment  of the  meeting  unless the Board  fixes a new record  date for the
adjourned  meeting.  The Board  shall fix a new  record  date if the  meeting is
adjourned for more than forty-five (45) days.

         If no  record  date  is  fixed  by  the  Board,  the  record  date  for
determining  stockholders  entitled  to  notice  of or to vote at a  meeting  of
stockholders  shall  be at the  close  of  business  on the  business  day  next
preceding the day on which notice is given or, if notice is waived, at the close
of business on the business day next  preceding  the day on which the meeting is
held. The record date for  determining  stockholders  for any purpose other than
set forth in this Section 7 or Section 9 of this Article I shall be at the close
of  business  on the day on which  the  Board  adopts  the  resolution  relating
thereto,  or the sixtieth day prior to the date of such other action,  whichever
is later.

         Section 8. CONSENT OF  ABSENTEES.  The  transactions  of any meeting of
stockholders,  however  called and noticed,  and wherever  held, are as valid as
though had at a meeting duly held after regular call and notice,  if a quorum is
present  either  in  person  or by  proxy,  and if,  either  before or after the
meeting,  each of the  persons  entitled  to vote,  not  present in person or by
proxy,  signs a written  waiver of notice,  or a consent  to the  holding of the
meeting or an approval of the minutes  thereof.  All such  waivers,  consents or
approvals  shall  be  filed  with the  corporate  records  or made a part of the
minutes of the meeting.  Attendance of a person at a meeting shall  constitute a
waiver  of  notice of and  presence  at such  meeting,  except  when the  person
objects,  at the beginning of the meeting,  to the  transaction  of any business
because  the  meeting  is not  lawfully  called  or  convened  and  except  that
attendance  at a  meeting  is  not a  waiver  of  any  right  to  object  to the
consideration  of matters  required by the Nevada General  Corporation Law to be
included in the notice but not so included,  if such objection is expressly made
at the meeting.  Neither the business to be transacted at nor the purpose of any
regular or special  meeting of  stockholders  need be  specified  in any written
waiver of notice,  consent  to the  holding of the  meeting or  approval  of the
minutes thereof.

         Section 9. ACTION  WITHOUT  MEETING.  Subject to Section  78-320 of the
Nevada General  Corporation Law, any action which,  under any provision of these
Bylaws of the  Nevada  General  Corporation  Law,  may be taken at any annual or
special  meeting of  stockholders,  may be taken  without a meeting  and without
prior notice of a consent in writing,  setting forth the action so taken,  shall
be signed by the holders of outstanding  shares having not less than the minimum
number of votes that would be  necessary  to  authorize or take such action at a
meeting at which all shares  entitled to vote  thereon  were  present and voted.
Unless a record  date for voting  purposes  be fixed as provided in Section 7 of
this  Article,  the record date for  determining  stockholders  entitled to give
consent  pursuant to this  Section 7, when no prior action by the Board has been
taken,  shall be the day on which  the first  written  consent  is given.  In no
instance  where  action is  authorized  by  written  consent  need a meeting  of
stockholders  be called or notice given.  The written consent must be filed with
the minutes of proceedings of the stockholders of the corporation.

         Section 10. PROXIES. Every person entitled to vote shares has the right
to do so  either in person  or by one or more  persons  authorized  by a written
proxy executed by such stockholder and filed with the Secretary.  Any proxy duly
executed is not revoked and  continues in full force and effect until revoked by
the person executing it prior to the vote pursuant thereto.  Such revocation may
be  effected  either,  (i)  by a  writing  delivered  to  the  Secretary  of the
Corporation  stating  that the  proxy is  revoked,  (ii) by a  subsequent  proxy
executed by the person  executing  the prior proxy and presented to the meeting,
or (iii) by  attendance  at the  meeting  and  voting in  person  by the  person
executing the prior proxy and  presented to the meeting,  or (iii) by attendance
at the meeting and voting in person by the person executing the proxy; provided,
however, that no proxy shall be valid after the expiration of eleven months from
the date of its execution unless otherwise provided in the proxy.

         Section  11.   INSPECTORS  OF  ELECTION.   In  advance  of  or  at  the
commencement  of any meeting of  stockholders,  the Board or the Chairman of the
Board  may  appoint  inspectors  of  election  to act at  such  meeting  and any
adjournment  thereof.  If inspectors of election be not so appointed,  or if any
persons so  appointed  fail to appear or refuse to act, the chairman of any such
meeting may, and on the request of any stockholder or stockholder's proxy shall,
make such  appointment at the meeting.  The number of inspectors shall be either
one or  three.  If  appointed  at a  meeting  on  the  request  of  one or  more
stockholders or proxies,  the majority of shares present shall determine whether
one or three inspectors are to be appointed.

         The duties of such inspectors shall include:  determining the number of
shares  outstanding  and the  voting  power  of  each;  determining  the  shares
represented at the meeting;  determining the existence of a quorum;  determining
the authenticity,  validity and effect of proxies;  receiving votes,  ballots or
consents;  hearing and  determining  all  challenges  and  questions  in any way
arising in connection with the right to vote;  counting and tabulating all votes
or consents; determining when the polls shall close; determining the result; and
doing such acts as may be proper to conduct the  election or vote with  fairness
to all  stockholders.  If there are three inspectors of election,  the decision,
act or  certificate  of a majority is effective in all respects as the decision,
act or certificate of all.

         Section 12.  STOCKHOLDERS  LIST. At each meeting of the  stockholders a
full,  true and complete list, in alphabetical  order,  of all the  stockholders
entitled to vote at such meeting,  and  indicating  the number of shares held by
each,  certified  by the  Secretary of the  corporation  or by any employee of a
Transfer Agent duly  appointed to act as such by the Board,  shall be furnished.
Only the persons in whose names shares of stock are  registered  on the books of
the corporation on the record date for the meeting,  as evidenced by the list of
stockholders so furnished, shall be entitled to attend and vote at such meeting.
Proxies and powers of attorney to vote must be filed with the  Secretary  of the
corporation before an election or a meeting of the stockholders,  or they cannot
be used at such election or meeting.

         Section 13. CONDUCT OF MEETINGS. The Chairman of the Board, if there be
such an officer,  or the President  shall preside as chairman at all meetings of
the stockholders. The chairman shall conduct each such meeting in a businesslike
and fair manner,  but shall not be obligated to follow any technical,  formal or
parliamentary  rules or  principles  of  procedure.  The  chairman's  rulings on
procedural  matters shall be conclusive and binding on all stockholders,  unless
at the time of a ruling a request for a vote is made to the stockholders holding
shares  entitled to vote and which are  represented in person or by proxy at the
meeting,  in which case the  decision  of a  majority  of such  shares  shall be
conclusive and binding on all  stockholders.  Without limiting the generality of
the  foregoing,  the chairman shall have all of the powers usually vested in the
chairman of a meeting of stockholders.

                             ARTICLE II - DIRECTORS

         Section  1.  (a)  NUMBER  AND  TERM.  The  Board  of  Directors  of the
corporation  shall  consist of and be fixed at  exactly  five (5)  persons  who,
subject to the provisions  for certain  stockholders  to designate  Directors as
contemplated below, shall be elected by the stockholders annually, at the annual
meeting of the corporation's  stockholders,  and who shall hold office until the
next annual meeting of stockholders  and until their  successors are elected and
shall  qualify.  Pursuant  to certain  contractual  agreements  by and among the
corporation  and  certain  of its  stockholders  pursuant  to  which  Prime  (as
hereinafter  defined) acquired certain of its shares of stock of the corporation
(collectively,  the  "Voting  Agreement"),  two  (2) of the  five  (5)  Director
positions  shall be occupied by  individuals  designated  by a majority  vote of
shares  held  by  stockholders  of the  corporation  excluding  shares  held  by
Prime/BDR  Acquisition,  L.L.C., a Delaware limited  liability company ("Prime")
(and any entity controlled by,  controlling or under common control with Prime),
and the remaining three (3) Director  positions shall be occupied by individuals
designated by Prime. Pursuant to the Voting Agreement, at any time, Prime or all
the other stockholders other than Prime (the "Other Stockholders") designating a
Director shall be entitled,  upon written notice to all other  stockholders,  to
remove and replace any one or more Directors occupying a position subject to its
or their  designation  rights. In the event that less than all of the holders of
any  capital  stock  shall be a party to the Voting  Agreement,  the  provisions
contained  herein shall control;  provided,  however,  that the Voting Agreement
shall be  enforceable  among the parties  thereto  (including  the  corporation)
according  to its terms and shall not be  amended,  altered or  affected  by the
provisions  hereof in any way. The terms of the Voting Agreement shall be deemed
incorporated into these Bylaws for purposes of electing Directors. Any action by
the Other  Stockholders with respect to the election,  removal or replacement of
the two (2) Directors  that may be designated  by the Other  Stockholders  shall
require the  affirmative  vote of Other  Stockholders  holding a majority of the
shares of stock held by all Other Stockholders.

     (b)  QUALIFICATIONS.  Directors  shall be natural  persons age 18 or older.
Directors need not be stockholders of the corporation,  and need not be citizens
of the United States.

         Section  2.  AUTHORITY.  The  Board of  Directors  is  vested  with the
complete and unrestrained  authority in the management of all the affairs of the
corporation, and is authorized to exercise for such purpose as the general agent
of the corporation, its entire corporate authority.

         Section  3.  FILLING  VACANCIES.  When any  vacancy  occurs  among  the
Directors by death, resignation, disqualification, an increase in the authorized
number of directors, or other cause, the stockholders, at any regular or special
meeting,  or at any  adjourned  meeting  thereof,  as  provided  in  the  Voting
Agreement,  shall elect a successor to hold office for the unexpired  portion of
the term of the Director  whose place shall have become  vacant and until his or
her successor shall have been elected and shall qualify.

         Section 4. PLACE AND TIME OF MEETINGS. Meetings of the Directors may be
held at the  principal  office  of the  corporation  designated  by the Board of
Directors,  whether  within or without the State of Nevada or the United States,
at any time set forth in notice of meeting  given as provided  in these  Bylaws.
Meetings of the Directors may also be held elsewhere at such place or places and
at such time or times as the Board of Directors may from time to time determine,
or as shall be set  forth in a notice  of  meeting  given as  provided  in these
Bylaws, unless by special resolution the Board shall restrict or limit the place
or dates and time at which meetings of the Board are to be held.

         Section 5.   ANNUAL, REGULAR AND SPECIAL MEETINGS; NOTICE

         (a) Without  notice or call,  the Board of Directors may hold its first
annual  meeting  for the  year  immediately  after  the  annual  meeting  of the
stockholders  or  immediately  after the  election of  Directors  at such annual
meeting.

         (b) Regular  meetings of the Board of  Directors,  not more  frequently
than once each month, may be held at the principal office of the corporation, or
elsewhere,  as  scheduled by action of the Board of Directors by its Chairman of
the Board or its  President.  Notice of such regular  meetings shall be given by
regular  mail,  by  telephone  if  the  person  is  successfully  contacted,  by
telegraph,  by  facsimile  telephone  written  communication,  or by delivery in
person via courier service, to each Director by the President,  the Secretary or
any  Assistant  Secretary at least ten (10) business days prior to the day fixed
for such meetings;  but no regular  meeting or any action taken thereat shall be
held void or invalid if such notice is not given to any Director that (i) was in
attendance at a meeting of the Board of Directors which fixed the time, date and
place of such regular  meeting of the Board of Directors;  or (ii) waives notice
of the regular  meeting;  or (iii)  attends the regular  meeting in person or by
telephone  conference  call;  or (iv)  executes a consent to action taken at the
meeting after having received the minutes of such regular meeting.

         (c) Special  meetings of the Board of Directors may be held on the call
of the Chairman of the Board,  if there be such an officer,  the President,  the
Secretary or any Assistant  Secretary on at least  seventy-two  (72) hours prior
written notice to all Directors.  Notice of such special meetings shall be given
by regular  mail (but only if mailed at least seven (7)  business  days prior to
such special meeting), by telephone if the person is successfully  contacted, by
telegraph,  by  facsimile  telephone  written  communication,  or by delivery in
person via courier service, to each Director by the President,  the Secretary or
any  Assistant  Secretary;  but no regular  meeting or any action taken  thereat
shall be held void or invalid if such notice is not given to any  Director  that
(i) was in  attendance  at a meeting of the Board of  Directors  which fixed the
time, date and place of such special meeting of the Board of Directors;  or (ii)
waives notice of the special  meeting;  or (iii) attends the special  meeting in
person or by telephone  conference  call;  or (iv)  executes a consent to action
taken at the meeting after having received the minutes of such special meeting.

         (d)  Provided a quorum  shall be  present,  any meeting of the Board of
Directors,  no matter where held,  at which all of the members shall be present,
even though  without  notice,  or of which  notice shall have been waived by all
absentees,  shall be valid for all purposes  unless  otherwise  indicated in the
notice calling the meeting or in the waiver of notice.  Any and all business may
be  transacted  by any  meeting  of the Board of  Directors,  either  regular or
special.

         Section 6. ADJOURNMENT. A majority of the directors present, whether or
not a quorum is present,  may adjourn any directors  meeting to another time and
place.  Notice of the time and place of holding an adjourned meeting need not be
given  to  absent  directors  if the time  and  place  be  fixed at the  meeting
adjourned,  except as provided in the next sentence. If the meeting is adjourned
for more than 24 hours, notice of any adjournment to another time or place shall
be given prior to the time of the  adjourned  meeting to the  directors who were
not present at the time of the adjournment.

         Section 7. PARTICIPATION IN MEETINGS BY CONFERENCE  TELEPHONE.  Members
of the Board may participate in a meeting through use of conference telephone or
similar communications  equipment,  so long as all members participating in such
meeting can hear and speak to one another.

         Section 8. WAIVER OF NOTICE.  Notice of a meeting  need not be given to
any director who signs a waiver of notice or a consent to holding the meeting or
an approval of the minutes thereof,  whether before or after the meeting, or who
attends the meeting.  All such waivers,  consents and  approvals  shall be filed
with the corporate records and made a part of the minutes of the meeting.

         Section 9. ACTION WITHOUT MEETING.  Any action required or permitted to
be taken by the Board may be taken without a meeting if all members of the Board
shall  individually  or  collectively  consent in writing to such  action.  Such
consent or consents  shall have the same effect as a unanimous vote of the Board
and shall be filed with the minutes of the proceedings of the Board.

         Section 10. QUORUM AND VOTING.  A majority of the Board of Directors in
office shall  constitute a quorum for the  transaction  of business,  but at any
meeting of the Board at which there is less than a quorum present, a majority of
those  present may adjourn such meeting from time to time,  until a quorum shall
be  present,  and no notice of' such  adjournment  shall be  required  except as
provided by Section 6 of this Article II. The Board Director may prescribe rules
not in conflict with these  By-Laws for the conduct of its  business.  Except as
otherwise  expressly  set  forth  in these  Bylaws,  the  affirmative  vote of a
majority of the Directors shall  constitute an action validly taken by the Board
of Directors.

         Notwithstanding  the  foregoing,  the following  acts and  transactions
shall require the affirmative  vote of not less than eighty percent (80%) of the
Directors:

(a)  Issuance  of any  capital  stock of the  corporation  (or rights to acquire
     capital  stock,  through  conversion,  exchange,  exercise  of  options  or
     otherwise); and\

(b)  The  election,  removal  or  replacement  of the  President  and CEO of the
     corporation or of any Chairman of the Board;

(c)  Any increase or decrease in the facility  fees charged by the  corporation;
     and

(d)  Appointments  to,  replacements  of, or removals from, the Medical Advisory
     Board established pursuant to the authority set forth in Section 13 of this
     Article.

         Section  11.  PRESUMPTION  OF  ASSENT.  A director  of the  corporation
present at a meeting of the directors at which action on any corporate matter is
taken shall be presumed to have assented to the action taken as reflected in the
minutes of the meeting,  unless his abstention from voting or dissenting vote is
entered  in the  minutes  of the  meeting  or unless he shall  file his  written
dissent to such action with the person  acting as the  Secretary  of the meeting
before the  adjournment  thereof.  Such right to dissent  shall not apply to any
director who voted in favor of such action.

         Section 12. COMMITTEES. The Board of Directors shall not have authority
to designate its powers to an Executive  Committee.  The Board of Directors may,
by  resolution  passed by a majority of the whole Board,  designate  one or more
other  committees  of the Board (other than an Executive  Committee)  including,
without limitation,  an Audit Committee and/or a Compensation  Committee,  which
committees, to the extent provided in the resolution or resolutions of the Board
or in the  Bylaws  of the  corporation  as then in  effect,  shall  have and may
exercise the powers of the Board of Directors in the business and affairs of the
corporation,  and may have the power to authorize the seal of the corporation to
be affixed to all papers on which the corporation desires to place its corporate
seal,  if such a corporate  seal shall exist.  Any such  committee or committees
must have such name or names as shall be stated in the Bylaws of the corporation
then in effect or as may be determined  from time to time by resolution  adopted
by the Board.  Each such  committee  must include at least one (1) member of the
Board of Directors, and the Board of Directors by resolution may appoint natural
persons who are not Directors to serve as regular or alternate members on one or
more of such committees;  provided,  however,  that any committee  authorized to
administer stock option or stock plans of the corporation  shall consist only of
persons  who  are  members  of  the  Board  of  Directors.  Notwithstanding  the
foregoing,  the  Board of  Directors  may not  delegate  any of its  powers to a
committee  or  committees,  the affect of which  would allow such  committee  or
committees  to  authorize  any of the acts or  transactions  which  require  the
affirmative of not less than eighty percent (80%) of the Directors as set for in
Section 10 of this Article,  unless such committee or committees shall have been
established by resolution  passed by the affirmative vote of not less than eight
percent (80%) of the Directors.

         The  Board  shall  have the  power to  prescribe  the  manner  in which
proceedings of any such committee shall be conducted. In the absence of any such
prescription,  such  committee  shall have the power to prescribe  the manner in
which its  proceedings  shall be conducted.  Unless the Board or such  committee
shall otherwise  provide,  the regular and special meetings and other actions of
any  such  committee  shall  be  governed  by the  provisions  of  this  Article
applicable  to meetings and actions of the Board.  Minutes shall be kept of each
meeting of each committee.

         The Board of Directors shall designate an Audit  Committee,  such Audit
Committee shall meet  independently  with the  corporation's  internal  auditing
staff, with representatives of the corporation's  independent  accountants,  and
with representatives of senior management,  in each instance not less frequently
than once each fiscal year. The Audit  Committee  shall also. be responsible for
reviewing  the  general  scope of the  audit,  the fee  charged  by  independent
accountants, and matters relating to internal control systems and procedures.

         If the Board of Directors shall designate a Compensation Committee, the
Compensation  Committee shall be, responsible for reviewing and reporting to the
Board on the recommended annual  compensation for all officers and for preparing
any reports on  compensation  policies  required by rules and regulations of the
Securities and Exchange Commission to which the corporation is subject.

         Section  13.  MEDICAL  ADVISORY  BOARD.  The Board of  Directors  shall
establish a Medical  Advisory Board,  the size and composition of which shall be
established by resolution passed by the affirmative vote of not less than eighty
percent (80%) of the Directors.  Members of the Medical  Advisory Board who need
not be members of the Board of  Directors  or officers of the  corporation.  The
Medical  Advisory  Board shall meet at such time or times as it may, by majority
vote of its  members,  elect and may adopt  procedures  for the  conduct  of its
meetings.  The Medical  Advisory  Board's role shall be to provide advice to the
Board of Directors on decisions relating to equipment  purchases,  technological
obsolescence, quality assurance, credentialing and such other matters respecting
the medical  aspects of the  corporation's  business as it shall determine or as
shall be requested by the Board of Directors.  The Medical  Advisory Board shall
have no  authority to bind the  corporation  or the Board of  Directors.  Unless
otherwise  established  by a  resolution  adopted by at least a majority  of the
members of the  Medical  Advisory  Board,  the  majority  of the  members of the
Medical  Advisory  Board shall  constitute  a quorum of the  transaction  of its
business and the affirmative  vote of the majority of the members of the Medical
Advisory Board shall constitute action validly taken by that body.

         Section 14. EXPENSES AND COMPENSATION.

         (a) The  Directors  shall  be  allowed  and  paid  all  reasonable  and
necessary   expenses  incurred  in  attending  any  meeting  of  the  Board.  In
determining  whether  specific  items of expense are  reasonable in amount,  the
Board may from time to time establish policies as the type of airline travel and
hotel  accommodations  for which  reimbursement  of expenses will be paid by the
corporation.

         (b) The Board of Directors  may fix the  compensation  of directors for
services to the  corporation  as  directors,  as members of a  committee  of the
Board, or in any other  capacity.  Provided,  however,  that Directors shall not
receive  compensation  for their services as Directors  except as authorized and
approved  at a meeting  of the Board of  Directors  at which at least  two-third
(2/3) of the then duly elected and acting Directors shall be in attendance,  and
only  with the  affirmative  vote and  approval  at such  meeting  of at least a
majority of the Directors then duly elected and acting.

         Section 15. REPORT TO STOCKHOLDERS AND RATIFICATION BY STOCKHOLDERS.

         (a) The Board of  Directors,  acting  through a  representative  of the
Board or by the Chairman of the Board or the President,  if such person shall be
a Director,  shall make a report to the  stockholders  at annual meetings of the
stockholders of the condition of the corporation, and shall, on request, furnish
each of the stockholders with a true copy thereof. The requirement of furnishing
a copy of a statement of the condition of the corporation  shall be satisfied if
annual  report  with  financial  statements  for  the  last  fiscal  year of the
corporation  is  provided  to  stockholders  of record at or prior to the annual
meeting.

         (b) The Board of Directors, in its discretion,  may submit any contract
or act for  approval  or  ratification  at any annual or special  meeting of the
stockholders  called for the purpose of  considering  any such  contract or act,
which, if approved,  or ratified by the vote of the holders of a majority of the
capital stock represented in person or by proxy at such meeting, provided that a
lawful quorum of stockholders be there represented in person or by proxy,  shall
be valid and binding upon the corporation and upon all the stockholders thereof,
as if it had been approved or ratified by every stockholder of the corporation.

         Section  16.  RIGHTS  OF  INSPECTION.  Every  director  shall  have the
absolute right at any reasonable time to inspect and copy all books, records and
documents  of  every  kind  and  to  inspect  the  physical  properties  of  the
corporation and also of its subsidiary  corporations,  domestic or foreign. Such
inspection  by a  director  may be made in  person or by agent or  attorney  and
includes the right to copy and obtain extracts.

                     ARTICLE III - OFFICERS AND THEIR DUTIES

         Section 1. DESIGNATION AND ELECTION OF OFFICERS AND AGENTS.  Subject to
the provisions of ARTICLE II,  Section 10, the Board of Directors,  at its first
meeting after the annual  meeting of  stockholders,  shall elect a President,  a
Secretary  and a  Treasurer,  to hold  office at the  pleasure of the Board and,
unless  removed  without  or  without  cause  by  the  Board,  for a  period  of
approximately  one (1) year until the next annual meeting of the Board and until
their  successors are elected and qualify.  The Board of Directors may from time
to time, by resolution,  appoint such additional officers, and agents, including
without  limitation  a  Chairman  of  the  Board,  Vice  Presidents,   Assistant
Secretaries,  Assistant Treasurers and transfer agents as it may deem advisable.
The Board shall have  authority to  prescribe  the duties of all officers and to
fix their  compensation,  and all such  appointed  officers  shall be subject to
removal at any time by the Board of Directors. All officers,  agents and factors
shall be chosen and  appointed in such  manner,  and shall hold their office for
such terms as the Board of Directors may by resolution prescribe.

         No officer  other than the  Chairman of the Board,  if such  officer is
elected, shall be required to be a member of the Board of Directors.  Any person
may hold more than two or more offices.

         All officers  shall serve at the pleasure of the Board of Directors and
any person may be removed from office by action of the Board of Directors at any
time,  either with or without  cause.  Any vacancy in any of said offices may be
filled by the Board of Directors or, at the discretion of the Board, may be left
vacant  except  that the  corporation  shall at all times  have a  President,  a
Secretary and a Treasurer.

         Section 2. CHAIRMAN OF THE BOARD. The Chairman of the Board, if such an
officer shall be designated  and elected by the Board,  shall act as chairman of
the Board and shall  preside at all meetings of the Board of  Directors  and the
stockholders.  The  Chairman  of the  Board  shall  have  authority  to sign the
Certificates  of  Stock  issued  by  the  corporation,  bills  of  exchange  and
promissory  notes of the  corporation,  and shall  perform  such other duties as
shall be prescribed by the Board of Directors. If so designated by resolution of
the  Board of  Directors,  the  Chairman  of the Board  shall  also be the chief
executive officer of the corporation and shall have the supervision and, subject
to the control of the Board of  Directors,  the  direction of the  corporation's
affairs,  with full power to execute all  resolutions and orders of the Board of
Directors not especially entrusted to some other officer of the corporation.

         Section 3. PRESIDENT.  Unless such duties are assigned by resolution of
the Board to a Chairman of the Board, if there be such an officer, the President
shall be the chief  executive  officer  of the  corporation  and shall  have the
supervision and, subject to the control of the Board of Directors, the direction
of the  corporation's  affairs,  with full power to execute all  resolutions and
orders of the Board of Directors not especially  entrusted to some other officer
of the corporation. If there shall not be a Chairman of the Board, the President
shall also preside at all meetings of the Board of Directors  and  stockholders.
If the  Chairman of the Board shall also preside at all meetings of the Board of
Directors and  stockholders.  If the Chairman of the Board shall be appointed as
the corporation's chief executive officer, then the President shall be the chief
operating officer of the corporation and shall have the supervision and, subject
to the  control of the  Chairman  of the Board and the Board of  Directors,  the
direction of the corporation's  day-to-day business affairs,  with full power to
execute all  resolutions  and orders of the Board of  Directors  not  especially
entrusted to some other officer of the  corporation.  The  President  shall have
authority to sign the Certificates of Stock issued by the corporation,  bills of
exchange and promissory notes of the  corporation,  and shall perform such other
duties as shall be prescribed by the Board of Directors.

         Section  4.  VICE  PRESIDENTS.  In the  absence  or  disability  of the
President,  the Vice Presidents in order of their rank as fixed by the Board or,
if not so ranked,  any such Vice President,  shall perform all the duties of the
President  and,  when so acting  shall have all the powers of, and be subject to
all the  restrictions  upon, the President.  The Vice Presidents shall have such
other  powers  and  perform  such  other  duties  as from  time  to time  may be
prescribed for them respectively by the Board. The Board may designate  specific
functions or areas of responsibility for any Vice President by resolution of the
Board and/or by specifying at the time of his or her election that such person's
Vice  President  title and office  include a  designation  of such  function  or
general  area of  responsibility;  the  authority  of any  such  person  in said
designated functions and areas of responsibility shall be subject to the control
of the  Board  of  Directors  and to  right of  supervision  conferred  upon the
Chairman of the Board and the  President of the  corporation.  In the absence or
inability  to act of the  Chairman  of the  Board  and the  President,  any Vice
President  shall have authority to sign the  Certificates of Stock issued by the
corporation.

         Section 5. TREASURER.  The Treasurer shall have the  responsibility for
depositing  all moneys and other  valuables in the name and to the credit of the
corporation  with  such  depositaries  as may be  designated  by the  Board  and
otherwise  protecting  the  custody  of all  the  funds  and  securities  of the
corporation. The Treasurer shall have the care and custody of the stocks, bonds,
certificates,  vouchers,  evidence of debts, securities, and such other property
belonging to the  corporation as the Board of Directors  shall  designate.  When
necessary or proper,  he or she shall endorse on behalf of the  corporation  for
collection checks,  notes, and other  obligations.  The Treasurer shall disburse
the funds of the  corporation as may be ordered by the Board.  In the absence of
the Chairman of the Board and the President,  the Treasurer shall sign on behalf
of  the  corporation  all  bills  of  exchange  and  promissory   notes  of  the
corporation; he or she shall sign all papers required by law or by these By-Laws
or the Board of Directors to be signed by the Treasurer,  and shall perform such
other duties as shall be prescribed by the Board of Directors.

         Whenever  required  by the Board of  Directors  or the  President,  the
Treasurer shall render a statement of the corporation's cash account, an account
of  all  transactions  as  Treasurer,  and  of the  financial  condition  of the
corporation. The Treasurer shall enter regularly in the books of the corporation
to be kept by him or her for the  purpose,  full and  accurate  accounts  of all
monies  received  and  paid by him or her on  account  of the  corporation.  The
Treasurer  shall at all  reasonable  times  exhibit  the books of account to any
Director or the president of the corporation  during  business hours,  and shall
perform all acts incident to the position of Treasurer subject to the control of
the Board of Directors.

         The Treasurer  shall, if required by the Board of Directors,  give bond
to the corporation  conditioned  for the faithful  performance of all his or her
duties as Treasurer in such sum, and with such  security as shall be approved by
the Board of Directors, the expense of such bond to be borne by the corporation.

         Section 6. ASSISTANT TREASURERS. The Board of Directors may appoint one
or more Assistant  Treasurers who shall have such powers and perform such duties
as may be  prescribed  by the  Treasurer of the  corporation  or by the Board of
Directors or the President of the corporation. Any Assistant Treasurer shall, if
required by the Board of Directors, give bond to the corporation conditioned for
the faithful performance of all his or her duties as Assistant Treasurer in such
sum, and with such security as shall be approved by the Board of Directors,  the
expense of such bond to be borne by the corporation.

         Section 7.  SECRETARY.  The  Secretary  shall  keep the  minutes of all
meetings  of the Board of  Directors  and the  minutes  of all  meetings  of the
stockholders  in books provided for that purpose.  The Secretary shall attend to
the giving and  serving of all  notices of the  corporation;  he or she may sign
with the Chairman of the Board, the President or any Vice President, in the name
of the corporation,  all contracts  authorized by the Board of Directors;  he or
she shall have the custody of the corporate seal of the corporation, if there be
a corporate  seal;  he or she shall affix the such  corporate  seal, if there be
one,  to all  certificates  of stock duly issued by the  corporation;  he or she
shall have charge of the stock certificate books, stock transfer books and stock
ledgers,  and such other books and papers as the Board of Directors  may direct,
all of which shall at all  reasonable  times be open to the  examination  of any
Director  upon  application  at the office of the  corporation  during  business
hours;  and he or she shall, in general,  perform all the duties incident to the
office of Secretary and such other duties as shall be prescribed by the Board of
Directors.

         Section 8.  ASSISTANT  SECRETARIES.  The Board of Directors may appoint
one or more  Assistant  Secretaries  who shall have such powers and perform such
duties as may be prescribed by the Secretary or by the Board of Directors.

         Section 9. REPRESENTATION OF THE CORPORATION.  Unless otherwise ordered
by the Board of Directors, the Chairman of the Board or the President shall have
full power and authority in behalf of the  corporation  to attend and to act and
to vote at any meetings of the  stockholders  or holders of  indebtedness of any
corporation   in  which  the   corporation   may  hold  stock  or  evidences  of
indebtedness,  and at any such meetings,  shall possess and may exercise any and
all rights and powers  incident to the  ownership  of such stock or evidences of
indebtedness  which the  corporation  might  have  possessed  and  exercised  if
present.  The Board of Directors,  by resolution  from time to time,  may confer
like  powers on any person or persons in place of the  Chairman  of the Board of
the  President to  represent  the  corporation  for the purposes in this section
mentioned.

                           ARTICLE IV - CAPITAL STOCK

         Section 1. AUTHORITY OF THE BOARD. The capital stock of the corporation
shall be issued in such  manner  and at such times and upon such  conditions  as
shall be prescribed by the Board of Directors;  provided, however, that issuance
of any capital stock (or any rights to acquire  capital stock) shall require the
affirmative  vote of  greater  than or  equal  to  eighty  percent  (80%) of the
directors then serving on the Board of Directors

         Section 2.  STOCK CERTIFICATES.

         (a) Every holder of shares of the corporation shall be entitled to have
a  certificate  signed in the name of the  corporation  by the  Chairman  of the
Board,  the President or a  Vice-President  and by the Treasurer or an Assistant
Treasurer or the Secretary or an Assistant  Secretary,  certifying the number of
shares and the class or series of shares owned by the stockholder. Any or all of
the signatures on the certificate  may be facsimile if the stock  certificate is
imprinted with the corporate  seal. If any officer,  transfer agent or registrar
who has signed or whose  facsimile  signature has been placed upon a certificate
shall have ceased to be such officer,  transfer  agent or registrar  before such
certificate is issued,  it may be issued by the corporation with the same effect
as if such person were an officer,  transfer  agent or  registrar at the date of
issue.

         (b)  Certificates  for shares may be issued prior to full payment under
such  restrictions  and for such  purposes as the Board may  provide,  provided,
however, that on any certificate issued to represent any partly paid shares, the
total  amount of the  consideration  to be paid  therefor  and the  amount  paid
thereon shall be stated or incorporated by reference to a document setting forth
the same.

         (c) Except as provided in this Section,  no new  certificate for shares
shall be issued in lieu of an old one  unless  the  latter  is  surrendered  and
cancelled  at the same time.  The Board may,  however,  if any  certificate  for
shares is alleged to have been lost, stolen or destroyed, authorize the issuance
of a new  certificate in lieu thereof,  and the corporation may require that the
corporation  be given a bond or other adequate  security and an  indemnification
agreement  sufficient to indemnify it against any claim that may be made against
the corporation (including expense or liability) on account of the alleged loss,
theft  or  destruction  of  such   certificate  or  the  issuance  of  such  new
certificate. The Board of Directors may, in its discretion, refuse to issue such
new or  duplicate  certificates  save  upon the  order  of a court of  competent
jurisdiction in such matter, anything herein to the contrary notwithstanding.

         (d) All certificates  evidencing stock in this corporation of any class
or series shall be  consecutively  numbered;  the name of the person  owning the
shares represented  thereby with the number of such shares and the date of issue
shall be entered on the corporation's books.

         (e) the Board of Directors may appoint a transfer agent and a registrar
of transfers  and may require all stock  certificates  to bear the  signature of
each transfer agent and such registrar of transfer.

         (f) The Board of Directors  shall have power and  authority to make all
such rules and  regulations not  inconsistent  herewith as it may deem expedient
concerning the issue,  transfer and  registration of certificates  for shares of
the capital stock of the corporation.

         Section   3.   CLOSING   OF  STOCK   TRANSFER   BOOKS  FOR  VOTING  AND
DISTRIBUTIONS.  The Stock Transfer Books shall be closed for all meetings of the
stockholders  for a  period  specified  by  the  Board  of  Directors  or by any
authorized  officer of the corporation acting pursuant to authority of the Board
of Directors or by any authorized  officer of the corporation acting pursuant to
authority of the Board of Directors,  for a period of not less than ten (10) and
not more than sixty (60) days  prior to such  meetings,  and shall be closed for
the  payment of  dividends  or other  distributions  by the  corporation  to its
stockholders  during such periods as from time to time may be fixed by the Board
of Directors.

         Section 4. NO PREEMPTIVE RIGHTS. No stockholder or subscriber to shares
of this corporation  shall be entitled to any preemptive or preferential  rights
to purchase  and/or  subscribe for any part of any shares which may be issued at
any time by this corporation.

                          ARTICLE V - OFFICES AND BOOKS

         Section 1.  RESIDENT AGENT, REGISTERED OFFICE IN NEVADA; OTHER OFFICES.

         (a) The corporation shall appoint and maintain a resident agent for the
corporation  in accordance  with the  provisions of Section 78.090 of the Nevada
General  Corporation  Law, who may be either a natural  person or a corporation,
resident or located in the State of Nevada.  The  resident  agent may be changed
from time to time by action of the Board of Directors. The street address of the
resident  agent where such agent  maintains an office for the service of process
upon this corporation  shall be the registered office of this corporation in the
State of Nevada (the "registered office").

         (b) The corporation may have a principal  office and such other offices
in the State of Nevada or any other state or territory as the Board of Directors
may designate from time to time.

         Section 2.  BOOKS AND RECORDS.

         (a) A copy  of  the  Articles  of  Incorporation  of  the  corporation,
certified  by the  secretary  of state of  Nevada,  a copy of the  Bylaws of the
corporation,  certified  by an  officer  of this  corporation,  and a  statement
setting out the name of the  custodian of the stock ledger or a duplicate  stock
ledger of this  corporation,  and the present and complete post office  address,
including street and number, where the stock ledger or duplicate stock ledger is
kept,  shall be kept and maintained at the registered  office of the corporation
in the State of Nevada.  All such documents  maintained at the registered office
of the corporation  shall be subject to inspection by any of the stockholders of
the corporation  upon reasonable  notice during  customary  business hours for a
proper purpose.

         (b) The stock ledger and stock transfer books of the corporation  shall
be kept at its principal  office,  either within or without the State of Nevada,
or at the offices of a stock  transfer  agent duly  authorized to act as such by
resolutions  adopted  by the  Board of  Directors.  The  stock  ledger  shall be
available for the  inspection of all who are authorized or have the right to see
the same in  accordance  with the Nevada  General  Corporation  Law, and for the
transfer of stock.

         (c) Any person who has been a stockholder of record of the  corporation
for at least six (6) months  immediately  preceding  his or her  demand,  or any
person holding, thereunto authorized in writing by the holders of, at least five
percent (5%) of all of the  corporation's  outstanding  shares entitled to vote,
upon at least five (5) days' written  demand is entitled to inspect in person or
by agent or attorney, during usual business hours, the stock ledger or duplicate
stock ledger of the  corporation,  whether kept in the registered  office of the
corporation in the State of Nevada or elsewhere in accordance with paragraph (a)
of this Section 2, and to make extracts therefrom.  An inspection  authorized by
this  paragraph  (c) may be denied to a  stockholder  or other  person upon such
person's refusal to furnish to the corporation an affidavit that such inspection
is not  desired for a purpose  which is in the  interest of a business or object
other than the business of the  corporation  and that such person has not at any
time  sold or  offered  for sale any list of  stockholders  or any  domestic  or
foreign  corporation or aided or abetted any person in procuring any such record
of  stockholders  for any such purpose.  In every  instance where an attorney or
other agent of a stockholder  seeks the right of inspection,  the demand must be
accompanied by a power of attorney as provided by Section  78.1059 of the Nevada
General Corporation Law.

         (d) All other  books and  records of the  corporation  shall be kept at
such places as may be  prescribed  by the Board of Directors or by the President
of the  Corporation  acting  pursuant  to  authority  conferred  by the Board of
Directors.

                           ARTICLE VI INDEMNIFICATION

         Section 1. DEFINITIONS. For the purposes of this Article, "agent' means
any person who is or was a  director,  officer,  employee  or other agent of the
corporation,  or is or was  serving  at the  request  of  the  corporation  as a
director, officer, employee or agent or another foreign or domestic corporation,
partnership,  joint  venture,  trust or  other  enterprise,  or was a  director,
officer,  employee  or agent of a foreign or  domestic  corporation  which was a
predecessor  corporation  of the  corporation  or of another  enterprise  at the
request of such  predecessor  corporation;  "proceeding"  means any  threatened,
pending  or  completed   action  or   proceeding,   whether   civil,   criminal,
administrative  or  investigative;  and "expenses"  includes without  limitation
attorneys'  fees and any  expenses of  establishing  a right to  indemnification
under Sections 4 or 5(c) of this Article.

         Section 2. INDEMNIFICATION IN ACTIONS BY THIRD PARTIES. The corporation
shall have power to indemnify  any person who was or is a party or is threatened
to be made a party to any proceeding (other than an action by or in the right of
the  corporation  to procure a judgment in its favor) by reason of the fact that
such person is or was an agent of the corporation,  against expenses, judgments,
fines,  settlements  and other  amounts  actually  and  reasonably  incurred  in
connection  with such  proceeding  if such  person  acted in good faith and in a
manner  such  persons  reasonably  believed to be in the best  interests  of the
corporation and, in the case of a criminal  proceeding,  had no reasonable cause
to believe the  conduct of such  person was  unlawful.  The  termination  of any
proceeding  by judgment,  order,  settlement,  conviction or upon a plea of nolo
contendere or its equivalent shall not, of itself, create a presumption that the
person  did not act in good faith and in a manner  which the  person  reasonably
believed to be in the best  interests of the  corporation or that the person had
reasonable cause to believe that the person's conduct was unlawful.

         Section  3.  INDEMNIFICATION  BY  ACTIONS  BY OR IN  THE  RIGHT  OF THE
CORPORATION.  The  corporation  shall have the power to indemnify any person who
was or is a party or is threatened to be made a party to any threatened, pending
or completed  action by or in the right of the corporation to procure a judgment
in its favor by  reason  of the fact that such  person is or was an agent of the
corporation, against expenses actually and reasonably incurred by such person in
connection with the defense or settlement of such action if such person acted in
good faith,  in a manner such person believed to be in the best interests of the
corporation and with such care,  including  reasonable inquiry, as an ordinarily
prudent person in a like position would use under similar circumstances

         Section 4.  INDEMNIFICATION  AGAINST  EXPENSES.  To the extent  that an
agent of the  corporation  has been  successful  on the merits in defense of any
proceeding  referred to in Sections 2 or 3 of this  Article or in defense of any
claim,  issue or matter therein,  and as otherwise  provided by authorization of
the Board of Directors or stockholders of this  corporation,  the agent shall be
indemnified  against expenses  actually and reasonably  incurred by the agent in
connection therewith.

         Section 5.  REQUIRED  DETERMINATIONS.  Any  indemnification  under this
Article  shall be made by the  corporation  only if  authorized  in the specific
case, upon a determination  that  indemnification  of the agent is proper in the
circumstances  because the agent has met the applicable  standard of conduct set
forth in Sections 2 or 3 of this Article, by:

     (a) A majority vote of a quorum consisting of directors who are not parties
to such proceeding; or

     (b) Approval of the stockholders, with the shares owned by the person to be
indemnified not being entitled to vote thereon; or

         (c)  The  court  in  which  such  proceeding  is or  was  pending  upon
application made by the corporation or the agent or the attorney or other person
rendering  services  in  connection  with  the  defense,  whether  or  not  such
application  by  the  agent,   attorney  or  other  person  is  opposed  by  the
corporation.

         Section 6. ADVANCE OF  EXPENSES.  Expenses  incurred in  defending  any
proceeding may be advanced by the corporation  prior to the final disposition of
such  proceeding  upon receipt of an undertaking by or on behalf of the agent to
repay such amount  unless it shall be  determined  ultimately  that the agent is
entitled to be indemnified as authorized in this Article.

         Section 7. OTHER INDEMNIFICATION.  No provision made by the corporation
to indemnify it or its subsidiary's directors or officers for the defense of any
proceeding,   whether  contained  in  the  Articles,  Bylaws,  a  resolution  of
stockholders  or  directors,  an agreement or  otherwise,  shall be valid unless
consistent  with this  Article  and  approved  by a majority  of the  Directors;
provided,  however, that any such agreement approved by a majority of the shares
of capital stock voted at any meeting  called to consider the same or by written
consent  of a  majority  of the  shares  entitled  to vote for the  election  of
directors  shall  supercede  the  provision of this Article to the extent of any
inconsistencies.  Nothing  contained in this  Article  shall affect any right to
indemnification  to which persons other than such  directors and officers may be
entitled by contract or otherwise.

         Section 8. FORMS OF INDEMNIFICATION  NOT PERMITTED.  No indemnification
or advance shall be made under this Article, except as provided in Sections 4 or
5(c), in any circumstances where it appears:

         (a) That it would be  inconsistent  with a provision  of the  Articles,
these  Bylaws,  a  resolution  of  the  stockholders  or a  written  contractual
agreement which prohibits or otherwise limits indemnifications; or

     (b) That it would be inconsistent with any condition expressly imposed by a
court in approving a settlement.

         Section 9. INSURANCE.  The corporation shall have power to purchase and
maintain  insurance  on  behalf  of any  agent of the  corporation  against  any
liability  asserted against or incurred by the agent in such capacity or arising
out of the agent's status as such whether or not the corporation  would have the
power to indemnify the agent against such liability under the provisions of this
Article.

         Section 10.  NONAPPLICABILITY TO FIDUCIARIES OF EMPLOYEE BENEFIT PLANS.
This Article does not apply to any  proceeding  against any trustee,  investment
manager or other fiduciary of an employee benefit plan in such person's capacity
as such,  even  though such  person may also be an agent of the  corporation  as
defined  in  Section I of this  Article.  The  corporation  shall  have power to
indemnify  such  trustee,  investment  manager or other  fiduciary to the extent
permitted by applicable law

                          ARTICLE VII OTHER PROVISIONS

         Section 1. AUTHORITY REQUIRED FOR COMMITMENTS IN EXCESS OF $250,000. No
agreement,  contract,  lease,  note, bond,  debenture or other obligation (other
than checks in payment of  indebtedness  incurred by  authority  of the Board of
Directors)  involving the payment of money or the credit of the  corporation for
more than Two Hundred Fifty Thousand  Dollars  ($250,000)  shall be made without
the authority of the Board of Directors.

         Section  2.  ENDORSEMENT  OF  DOCUMENTS;   CONTRACTS.  Subject  to  the
provisions  of applicable  law, any note,  mortgage,  evidence of  indebtedness,
contract,  option or warrants to purchase stock in this corporation,  conveyance
or other  instrument  in writing  and any  assignment  or  endorsements  thereof
executed or entered  into between the  corporation  and any other  person,  when
signed by the Chairman of the Board, the President or any Vice President and the
Secretary,  any Assistant Secretary, the Treasurer or any Assistant Treasurer of
the corporation  shall be valid and binding on the corporation in the absence of
actual  knowledge on the part of the other person that the signing  officers had
no  authority  to execute the same.  Any such  instruments  may be signed by any
other  person  or  persons  and in such  manner  as from  time to time  shall be
determined  by the Board,  and,  unless so  authorized  by the  Board,  no other
officer,  agent or  employee  shall  have any  power  or  authority  to bind the
corporation  by any contract or  engagement or to pledge its credit or to render
it liable for any purpose or amount.

         Section 3. STOCK PURCHASE  PLANS.  Subject to the provisions of Article
I, Section 4 of these  Bylaws,  the  corporation  may adopt and carry out one or
more stock  purchase  plans or  agreements  or stock option plans or  agreements
providing for the issue and sale of capital stock for such  consideration as may
be fixed of its unissued shares, or of issued shares acquired or to be acquired,
to one or more of the employees, officer or directors of, or consultants to, the
corporation  or of a  subsidiary  or to a trustee on their  behalf,  and for the
payment of such  shares in  installments  or at one time,  and may  provide  for
aiding any such persons in paying for such shares by  compensation  for services
rendered, promissory notes or otherwise

         Any such stock purchase plan or agreement or stock option plan or other
stock agreement may include, among other features, the fixing of eligibility for
participation  therein, the class and price of shares to be issued or sold under
the plan or  agreement,  the number of shares which may be  subscribed  for, the
method  of  payment  therefor,  the  reservation  of title  until  full  payment
therefor,  the effect of the termination of employment,  an option or obligation
on the part of the  corporation  to repurchase  the shares upon  termination  of
employment,  restrictions  upon  transfer of the shares,  the time limits of and
termination of the plan,  and any other matters,  not in violation of applicable
law, as may be included in the plain as approved or authorized,  by the Board or
any committee of the Board.

         Section 4. RESERVES AND  DIV1DENDS.  The Board of Directors  shall have
power to reserve over and above the capital  stock paid in, such amount,  in its
discretion  to fix as a  reserve  fund,  and may,  from  time to  time,  declare
dividends in excess of the amounts so reserved  subject to the provisions of the
Nevada  General  Corporation  Law, and pay the same to the  stockholders  of the
corporation,  and may  also,  if it deems  the  same  advisable,  declare  stock
dividends of the unissued capital stock.

         Section 5. DEPOSIT OF FUNDS.  Except for funds,  held in trust by third
parry fiduciaries, all monies of the corporation, shall be deposited when and as
received by the Treasurer or any other  employee or agent of the  corporation in
such bank or banks or other depositary as may from time to time be designated by
the  Board  of  Directors,  and such  deposits  shall be made in the name of the
corporation.

         Section  6.  BOARD   APPROVAL   REQUIRED   FOR  LOANS  TO  OFFICERS  OR
STOCKHOLDERS.  No loan or advance of money shall be made by the  corporation  to
any  stockholder  or officer of the  corporation,  unless the Board of Directors
shall otherwise  authorize;  the foregoing provision shall not apply to advances
for business  expenses  made in the ordinary  course of business to employees or
agents of the corporation who coincidentally are stockholders or officers of the
corporation.

         Section  7. BOARD  APPROVAL  REQUIRED  FOR  COMPENSATION  TO  EXECUTIVE
OFFICERS.  No executive  officer shall be entitled to any salary or compensation
for  any  services  performed  for  the  corporation,   unless  such  salary  or
compensation  shall be fixed by  resolution  of the Board of  Directors  or by a
committee  thereof  or  the  Chairman  of the  Board  or  the  President  of the
Corporation under authority  conferred by the Board. For the purposes hereof, an
executive  officer  shall be deemed to include the  Chairman  of the Board,  the
President,   any  Vice  President,  the  Secretary  and  the  Treasurer  of  the
corporation

         Section  8.  POWER TO DEAL IN  SECURITIES.  The  corporation  may take,
acquire,  hold,  mortgage,  sell,  or  otherwise  deal in  stocks  or  bonds  or
securities of any other corporation,  partnership, association or other business
entity, if and as often as the Board of Directors shall so elect.

         Section 9. POWER TO CREATE  SECURITY  INTERESTS;  STOCKHOLDER  APPROVAL
REQUIRE TO DISPOSE OF ALL ASSETS.  The  Directors  shall have power to authorize
and cause to be executed,  mortgages  and liens  without limit as to amount upon
the property and franchise of this corporation,  and pursuant to the affirmative
vote,  either  in person or by proxy,  of the  holders  of not less than  eighty
percent (80%) of the voting capital stock issued and outstanding;; the Directors
shall have  authority  to dispose  in any manner of the whole  property  of this
corporation.

     Section 10. CORPORATE SEAL. The corporation may have a corporate seal if so
authorized by resolution of the Board,  the design thereof being  established by
the Board.

         Section 11. FISCAL YEAR. The fiscal year of the  corporation  shall end
on  December  31 of each  year,  subject to the right of the Board to change the
fiscal year if determined by the Board to be appropriate.

                        ARTICLE VIII AMENDMENT OF BYLAWS

         Section 1.  Amendments  and changes of these  Bylaws may be made at any
regular or special  meeting the Board of  Directors at which a quorum is present
and acting,  by a vote of not less than eighty percent (80%) of the entire Board
of  Directors,  or may be made by a vote of, or a consent in writing  signed by,
the holders of not less than eighty percent (80%) of the issued and  outstanding
capital stock of the corporation.

                             [Certification follows]


<PAGE>


                            CERTIFICATION OF BYLAWS:

         The  undersigned,  being  a duly  elected  and  acting  officer  of the
corporation,  DOES HEREBY  CERTIFY  that the  foregoing  is a true,  correct and
complete copy of the Bylaws of the above  corporation as adopted and approved by
the Board of Directors of said  corporation  on September 1, 1999,  and that the
same  have not been  rescinded,  modified  or  amended  as of this  date of this
certificate.

         IN WITNESS WHEREOF,  I have set my hand and the seal of the corporation
as of September 1, 1999.


                                           Printed Name:  Mark R. Mandel

                                           Title:  Secretary


                        ASSIGNMENT AND SECURITY AGREEMENT

         THIS ASSIGNMENT AND SECURITY  AGREEMENT (this  "Agreement") is made and
entered into as of the 1st day of September,  1999, by and between Prime Medical
Operating,  Inc., a Delaware  corporation  (the  "Secured  Party") and Prime/BDR
Acquisition, L.L.C., a Delaware limited liability company (the "Debtor").

                                    RECITALS:

         A. Debtor and Secured Party have  executed and  delivered  that certain
Contribution  Agreement  dated  effective  September 1, 1999,  between and among
Debtor,  Secured Party,  Prime Medical Services,  Inc., a Delaware  corporation,
Prime/BDEC  Acquisition,  L.L.C., a Delaware limited liability  company,  Barnet
Dulaney Eye Center, P.L.L.C., an Arizona professional limited liability company,
LASIK Investors L.L.C., a Delaware limited liability company,  David D. Dulaney,
M.D., Ronald W. Barnet, M.D., and Mark Rosenberg (the "Contribution Agreement"),
and that certain Loan Agreement, dated September 1, 1999 (the "Loan Agreement"),
pursuant to which  Secured  Party agrees to make certain  loans to Debtor on the
terms and subject to the conditions provided therein.

         B. Secured Party has requested  that Debtor pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or  hereafter  have  to  Secured  Party,  including,   without  limitation,  any
obligations arising under loans made pursuant to the Loan Agreement.

     C. Debtor desires to enter into this Agreement as a material  inducement to
Secured Party's extension of credit under the Loan Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Debtor  acknowledges,  Debtor and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Debtor hereby assigns,  transfers, and
pledges to Secured  Party,  and Debtor hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

     (a) Interest in  Subsidiary.  All ownership  interests of Debtor in Horizon
Vision Center, Inc., a Nevada corporation  ("Horizon"),  whether now existing or
hereafter acquired and including,  without limitation, that certain 60% interest
in Horizon (the "Interests").


<PAGE>


                                        2




     (b) Interest in Acquisition Agreements. All of Debtor's interest and rights
(but not any obligations)  under those certain Stock Purchase  Agreements by and
between Debtor and the Shareholders of Horizon;

                  (c)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable  to any of the  Collateral  described in (a) and (b)above,  and all
rights of Debtor now or hereafter arising under any agreement  pertaining to the
Collateral  described in (a) and (b) above,  including  without  limitation  all
distributions,   proceeds,  fees,  dividends,  preferences,  payments  or  other
benefits of whatever nature which Debtor is now or may hereafter become entitled
to receive with respect to any Collateral described in (a) and (b) above;

                  (d) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Debtor
becomes  entitled  to receive  or shall  receive  in  connection  with any other
Collateral:  (i) any stock or other  ownership  certificate,  including  without
limitation,  any certificate representing a stock dividend or any certificate in
connection with any recapitalization,  reclassification,  merger, consolidation,
conversion,  sale of assets,  combination,  stock split, reverse stock split, or
spin-off;  (ii) any  option,  warrant,  subscription  or  right,  whether  as an
addition to or in substitution of any other  Collateral;  (iii) any dividends or
distributions  of any kind whatsoever,  whether  distributable in cash, stock or
other property;  (iv) any interest,  premium or principal payments;  and (v) any
conversion or redemption proceeds; and

                  (e) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral described in (a), (b), (c) or (d) above, including without limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Debtor to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
or  any  subsidiary  of  Secured  Party  (including,   without  limitation,  any
principal,  interest,  fees and other amounts,  and any other obligations) under
and  pursuant to this  Agreement  and/or the  Contribution  Agreement,  the Loan
Agreement,   each   promissory  note  issued  pursuant  to  the  Loan  Agreement
(collectively,  the  "Note"),  and/or any other  contract or  agreement  between
Secured Party (or any of its subsidiaries) and Debtor or any affiliate of Debtor
(collectively,  including the Contribution Agreement, the Loan Agreement and the
Note, the "Other Agreements"); and

                  (b) (i)  all  indebtedness,  obligations  and  liabilities  of
Debtor  and/or any  affiliate of Debtor to Secured  Party or any  subsidiary  of
Secured  Party of any kind or  character,  now  existing or  hereafter  arising,
whether direct, indirect,  related,  unrelated,  fixed, contingent,  liquidated,
unliquidated, joint, several or joint and several, arising from, connected with,
or  related  to the Other  Agreements,  or any  other  document,  agreement,  or
instrument  executed  in  connection  therewith,  (ii) all  accrued  but  unpaid
interest  on  any  of  the  indebtedness  described  in  (i)  above,  (iii)  all
obligations  of Debtor  and/or any  affiliate of Debtor to Secured  Party or any
subsidiary  of Secured  Party  under any  documents  or  agreements  evidencing,
securing,  governing  and/or  pertaining to all or any part of the  indebtedness
described in (i) and (ii) above, (iv) all costs and expenses incurred by Secured
Party or its  subsidiaries in connection with the collection and  administration
of all or any part of the  indebtedness  and obligations  described in (i), (ii)
and (iii) above or the protection or preservation  of, or realization  upon, the
collateral  securing  all or any  part of  such  indebtedness  and  obligations,
including  without  limitation  all  attorneys'  fees,  and  (v)  all  renewals,
extensions, modifications and rearrangements of the indebtedness and obligations
described in (i), (ii), (iii) and (iv) above.

                  (c) All sums now or  hereafter  loaned or  advanced by Secured
Party or any  subsidiary  of Secured Party to Debtor or any affiliate of Debtor,
or expended by Secured  Party or its  subsidiaries  for the account of Debtor or
its  affiliates or otherwise  owing by Debtor or its affiliates to Secured Party
or its subsidiaries,  in respect of the Obligations, and all other sums expended
or  advanced  by  Secured  Party  or its  subsidiaries  pursuant  to any term or
provision of this Agreement or any Other Agreement (i) to collect and/or enforce
the Obligations or (ii) to maintain, protect and preserve the Collateral.

                                   ARTICLE II

       DEBTOR'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

       Debtor hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Debtor has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Debtor  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3 No  Agreements.  The  Interests  are not  subject  to any  right of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Debtor or the issuer thereof is
bound.  No  restrictions  or  conditions  exist with  respect to the transfer or
voting of any securities pledged as Collateral.

                                   ARTICLE III

                  DEBTOR'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Debtor.  As of the date hereof,  (i) Debtor is and will
be solvent;  (ii) the fair saleable  value of Debtor's  assets  exceeds and will
continue  to exceed  Debtor's  liabilities  (both fixed and  contingent);  (iii)
Debtor  has  and  will  have  sufficient  capital  to  satisfy  all of  Debtor's
obligations as they become due; (iv) no receiver, trustee, or custodian has been
appointed for, or taken possession of, all or substantially all of the assets of
Debtor,  either in a  proceeding  brought by Debtor or in a  proceeding  brought
against Debtor; (v) Debtor is not the subject of a petition for relief under the
United States  Bankruptcy Code or any similar  federal or state  insolvency law,
including without limitation a petition filed by Debtor or a petition filed by a
third party seeking relief against  Debtor;  and (vi) Debtor has no intention of
filing a petition  for relief  under the United  States  Bankruptcy  Code or any
similar  federal  or state  insolvency  law,  or of  seeking  any other  form of
creditor relief,  within the two-year period  immediately  following the date of
this Agreement.

         3.2  Authority and  Compliance.  Debtor has full power and authority to
enter into this Agreement. Debtor has full power and authority to enter into and
perform  its  obligations  under each  Other  Agreement.  No further  consent or
approval is required as a condition  to the  validity of this  Agreement  or any
Other Agreement.  Debtor is in compliance with all applicable laws,  ordinances,
statutes, orders, regulations,  judgments, writs, or decrees of any governmental
entity to which it is subject.

         3.3  Binding  Agreement.   This  Agreement  and  each  Other  Agreement
constitute valid and legally binding  obligations of Debtor,  in accordance with
their terms, subject to the applicable bankruptcy,  insolvency,  reorganization,
moratorium, and similar laws affecting creditors' rights generally.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Debtor,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Debtor or upon
Debtor's  ability to perform its  obligations  under this Agreement or any Other
Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Debtor or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement or any Other Agreement.

         3.6  Ownership  of  Assets.  Debtor  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Debtor has filed all tax returns required to be filed by Debtor.

                                   ARTICLE IV

                  DEBTOR'S COVENANTS WITH RESPECT TO COLLATERAL

         Debtor  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Debtor  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Debtor's  endorsement  thereon and/or  accompanied by property
instruments of transfer and assignment duly executed in blank with, if requested
by Secured Party,  signatures  guaranteed by a member or member  organization in
good standing of an authorized Securities Transfer Agents Medallion Program, all
in form and substance satisfactory to Secured Party.

         4.2  Further  Assurances.   Debtor  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(d)  above,  received by Debtor shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Debtor,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Debtor and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Debtor  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Debtor nor any person acting on Debtor's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Debtor will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining to  Collateral.  Debtor will not enter into any
type of contract or agreement  pertaining to any of the Collateral or in any way
transfer any voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Debtor  will not  consent to or approve of the  issuance  of (i) any  additional
interests  or  shares  of any  class  of  securities  of such  issuer,  (ii) any
instrument  convertible  voluntarily by the holder thereof or automatically upon
the occurrence or non-occurrence of any event or condition into, or exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.

         4.9  Restrictions  on  Securities.  Debtor  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Debtor will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding the Interests  unless  consented to in writing by Secured
Party.

                                    ARTICLE V

                         DEBTOR'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees  that it shall  (i)  promptly  advise  Secured  Party in  writing  of any
litigation  filed against Debtor and of any condition,  event or act which comes
to its attention that would or might have a material  adverse effect on Debtor's
financial  condition  or on Debtor's  ability to perform the  Obligations,  (ii)
except  as  expressly   contemplated  in  Section  4.3(e)(i)  and  (ii)  of  the
Contribution  Agreement,  pay all available funds toward  repayment of the Note,
regardless  of whether  payment of such amounts  exceeds the  required  payments
under  the Note and  (iii) if  Borrower  uses any  proceeds  from the  Note,  to
acquire,  directly or indirectly,  a one hundred  percent  (100%)  interest in a
Target Center (as defined in the Contribution  Agreement),  Borrower shall cause
such  Target  Center to execute a  security  agreement,  acceptable  in form and
substance  to Lender,  granting  to Lender or one of Lender's  subsidiaries  the
highest available priority security interest in all of the assets of such Target
Center.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Debtor covenants and
agrees that Debtor will not, without the prior written consent of Secured Party:

     6.1 Liens. Grant, suffer, or permit liens on, or security interests in, the
Collateral.

         6.2  Violate  Other  Covenants.  Violate  or fail to  comply  with  any
covenants  or  agreements  regarding  other  debt  which  will or would with the
passage  of time or upon  demand  cause the  maturity  of any  other  debt to be
accelerated.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid  under  the  Loan  Agreement  (including,  without  limitation,  principal,
interest and fees due  thereunder),  or any other amount which Debtor may now or
hereafter  owe to Secured Party under any Other  Agreement or otherwise,  within
ten (10) calendar days after such amount is due;

                  (b) The  failure  of Debtor to pay any  Obligation  after such
amount is due (and, if applicable  under the terms of any contractual  agreement
creating or governing such  Obligation,  after the expiration of any cure period
expressly required);

     (c) Debtor's breach of a covenant in this Agreement or any other failure to
perform its obligations under this Agreement or any Other Agreement;

                  (d) Any  representation  or  warranty  made by  Debtor in this
Agreement or any Other Agreement between Debtor and Secured Party shall be false
or materially misleading,  as determined in the reasonable discretion of Secured
Party;

                  (e) Any event of default  shall  occur  under the terms of the
Loan  Agreement  and shall not be cured within the time  expressly  provided for
with respect thereto in the Loan Agreement;

                  (f) If Debtor or any other party  obligated to pay any portion
of the  Obligations:  (i)  becomes  insolvent,  or makes a transfer  in fraud of
creditors,  or makes an assignment  for the benefit of  creditors,  or admits in
writing its inability to pay its debts as they become due; (ii) generally is not
paying its debts as such debts  become due and  Secured  Party,  in good  faith,
determines that such event or condition  could lead to a material  impairment of
the Collateral, or any part thereof, or of any other payment security for any of
the Obligations;  (iii) has a receiver,  trustee or custodian  appointed for, or
take possession of, all or substantially  all of the assets of such party or any
of the  Collateral,  either  in a  proceeding  brought  by  such  party  or in a
proceeding  brought against such party and such appointment is not discharged or
such  possession  is not  terminated  within sixty (60) days after the effective
date thereof or such party  consents to or  acquiesces  in such  appointment  or
possession;  (iv) files a petition for relief under the United States Bankruptcy
Code or any other present or future federal or state  insolvency,  bankruptcy or
similar laws (all of the foregoing  hereinafter  collectively called "Applicable
Bankruptcy  Law") or an  involuntary  petition for relief is filed  against such
party under any Applicable  Bankruptcy Law and such involuntary  petition is not
dismissed  within  sixty  (60) days after the  filing  thereof,  or an order for
relief naming such party is entered under any Applicable  Bankruptcy Law, or any
composition, rearrangement, extension, reorganization or other relief of debtors
now or hereafter  existing is requested or consented to by such party; (v) fails
to  have  discharged  within  a  period  of  sixty  (60)  days  any  attachment,
sequestration  or similar writ levied upon,  or any claim  against or affecting,
any  property  of such party;  or (vi) fails to pay within  ninety (90) days any
final money judgment against such party; or

                  (g) The issuer of any securities constituting Collateral files
a petition  for relief  under any  Applicable  Bankruptcy  Law,  an  involuntary
petition  for  relief is filed  against  any such  issuer  under any  Applicable
Bankruptcy Law and such involuntary petition is not dismissed within thirty (30)
days after the filing thereof,  or an order for relief naming any such issuer is
entered under any Applicable Bankruptcy Law.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Debtor,  either in Secured Party's own right or in the name of Debtor
and in the same manner and to the same extent that Debtor  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Debtor arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Debtor,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (c) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Debtor hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Debtor's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Debtor and all
persons and corporations  lawfully  claiming by or through or under Debtor.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (d) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in any type of offering  which  complies  with, or is exempt from the
registration  requirements  of, the  Securities  Act of 1933 and any  applicable
state  securities laws, and no sale so made in good faith by Secured Party shall
be deemed to be not "commercially reasonable" because so made.

                  (e)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance with the terms hereof or under the  Contribution  Agreement or any
Other  Agreement;  (d)  then,  to or among the  amounts  of fees,  interest  and
principal then owing and unpaid in respect of the Obligations,  in such priority
as Secured Party may determine in its discretion;  and (e) the remainder of such
proceeds,  if  any,  shall  be  paid  to  Debtor.  If  such  proceeds  shall  be
insufficient to discharge the entire  Obligations,  Secured Party shall have any
other available legal recourse  against Debtor under, or for the performance of,
the  Contribution  Agreement and any Other Agreement  between Debtor and Secured
Party,  for the deficiency,  together with interest  thereon at the maximum rate
permitted under applicable law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due in accordance with the terms of any Other Agreement.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies  of the  Debtor,  in respect  to any of the  Collateral  or  agreements
pertaining thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Debtor hereby appoints
Secured Party as  attorney-in-fact  of Debtor,  with full authority in the place
and stead of Debtor and in the name of Debtor, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Debtor  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Debtor under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Debtor contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights  pertaining to any Collateral.  Without limiting the
generality of the foregoing,  Secured Party shall not have any obligation,  duty
or  responsibility  to do any of the  following:  (a) ascertain any  maturities,
calls,  conversions,  exchanges,  offers, tenders or similar matters relating to
the  Collateral or informing  Debtor with respect to any such matters;  (b) fix,
preserve  or  exercise  any  right,  privilege  or option  (whether  conversion,
redemption or otherwise) with respect to the Collateral; (c) collect any amounts
payable  in  respect  of the  Collateral;  (d)  sell all or any  portion  of the
Collateral,  for any reason;  or (e) hold the Collateral for or on behalf of any
party other than Debtor.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Debtor arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Debtor in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, DEBTOR SHALL AND
DOES AGREE TO INDEMNIFY, PROTECT, DEFEND AND HOLD HARMLESS SECURED PARTY AND ITS
SUBSIDIARIES,  AND EACH OF THEIR OFFICERS, DIRECTORS,  REPRESENTATIVES,  AGENTS,
EMPLOYEES,  LENDERS,  SUCCESSORS AND ASSIGNS,  FROM AND AGAINST ALL LIABILITIES,
CLAIMS, DAMAGES,  LOSSES, FINES, PENALTIES,  CAUSES OF ACTIONS, SUITS, JUDGMENTS
AND EXPENSES (INCLUDING COURT COSTS,  ATTORNEY'S FEES AND COST OF INVESTIGATION)
OF ANY  NATURE,  KIND OR  DESCRIPTION  OF ANY  PERSON  OR  ENTITY,  DIRECTLY  OR
INDIRECTLY,  ARISING OUT OF, CAUSED BY OR RESULTING  FROM (IN WHOLE OR IN PART),
ANY ACT OR  OMISSION  OF SECURED  PARTY,  OR ANYONE  ACTING ON BEHALF OF SECURED
PARTY,  IN CONNECTION  WITH THE  COLLATERAL,  INCLUDING  WITHOUT  LIMITATION ANY
MARKET FLUCTUATIONS IN THE COLLATERAL AS A RESULT OF SECURED PARTY'S SALE OF, OR
FAILURE TO SELL, THE INTERESTS AT ANY  PARTICULAR  TIME WHEN IT HAS THE RIGHT TO
DO  SO.  THE  FOREGOING  INDEMNITY  SHALL  SURVIVE  THE  EXPIRATION  OR  EARLIER
TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Debtor,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Debtor
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed and observed by Debtor under any Other Agreement,  or in respect
of the Collateral (subject to any applicable default cure period), Secured Party
(a) may but  shall not be  obligated  to take any  action  Secured  Party  deems
necessary  or  desirable  to  prevent  or remedy  any such  default by Debtor or
otherwise to protect the Security Interest,  and (b) shall have the absolute and
immediate right to take possession of the Collateral or any part thereof (to the
extent Secured Party has not previously taken  possession) to such extent and as
often as the Secured Party, in its sole discretion, deems necessary or desirable
in order to prevent  or to cure any such  default by  Debtor,  or  otherwise  to
protect the security of this Agreement. Secured Party may advance or expend such
sums of money for the account of Debtor as Secured Party in its sole  discretion
deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure  proceedings commenced and subsequently  abandoned or in any dispute
or litigation in which Secured Party or the holder of any of the Obligations may
become  involved  by reason of or  arising  out of any  Other  Agreement  or the
Collateral,  shall be a part of the  Obligations  and shall be paid by Debtor to
Secured  Party,  upon demand,  and shall bear interest until paid at the maximum
rate of interest  permitted by applicable law, from the date incurred by Secured
Party until repaid by Debtor.

         8.9. Convertible  Collateral.  Secured Party may present for conversion
any  Collateral  which is  convertible  into any other  instrument or investment
security or a  combination  thereof with cash,  but Secured Party shall not have
any duty to present for conversion any Collateral  unless it shall have received
from Debtor  detailed  written  instructions to that effect at a time reasonably
far in advance of the final conversion date to make such conversion possible.

         8.10 Secured Party's Right of Set-Off.  Upon the happening of any event
entitling  Secured  Party to pursue any remedy  provided  herein,  or if Secured
Party shall be served with garnishment process in which Debtor shall be named as
defendant,  whether or not Debtor  shall be in  default  hereunder  at the time,
Secured Party may, but shall not be required to, set-off any indebtedness  owing
by  Secured  Party  to  Debtor  against  any of the  Obligations  without  first
resorting to the security hereunder and without prejudice to any other rights or
remedies of Secured Party or its Security Interest.

         8.11 Remedies.  No right or remedy herein  reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.12 Debtor's Waivers.  Debtor waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.13 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Debtor waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Debtor  agrees that Secured  Party shall have no duty or obligation to Debtor to
apply to the Obligations any such other security or proceeds thereof.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Debtor their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:        1301 Capital of Texas Hwy., Suite C-300
                                        Austin, Travis County, Texas 78746
                                        Attn: President

                  with copy to:         Timothy L. LaFrey, Esq.
                                        Akin, Gump, Strauss, Hauer & Feld,L.L.P.
                                        1900 Frost Bank Plaza
                                        816 Congress Avenue
                                        Austin, Texas 78701

                  Debtor:               Prime/BDR Acquisition, L.L.C.
                                        1301 Capital of Texas Hwy., Suite C-300
                                        Austin, Travis County, Texas 78746
                                        Attn: President

         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Debtor if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Debtor.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Debtor shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Debtor  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Debtor shall be closed at any time, shall
be equally  applicable to any new  transactions  thereafter.  Provisions of this
Agreement,  unless  by their  terms  exclusive,  shall be in  addition  to those
contained in any Other Agreement.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval  or  consent.  Debtor  acknowledges  that  Lender  intends  to  make  a
collateral  assignment of its rights under this Agreement for the benefit of one
or more of its  lenders.  Debtor may not  assign  this  Agreement  or any of its
rights or  obligations  hereunder  without the express prior written  consent of
Secured Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

     9.10 ENTIRE AGREEMENT. THIS AGREEMENT, THE LOAN AGREEMENT, THE NOTE AND THE
CONTRIBUTION AGREEMENT REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY
NOT BE  CONTRADICTED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS,  OR SUBSEQUENT ORAL
AGREEMENTS OF THE PARTIES.  THERE ARE NO UNWRITTEN ORAL  AGREEMENTS  BETWEEN THE
PARTIES.

                            [Signature page follows]


<PAGE>


                                SIGNATURE PAGE TO

                                 ASSIGNMENT AND

                               SECURITY AGREEMENT

         EXECUTED this 1 day of September, 1999.

DEBTOR:                                     Prime/BDR Acquisition, L.L.C.

                                    By: /s/ David Dulaney, M.D.

                                    Printed Name: David Dulaney, M.D.

                                    Title:Manager, Prime/BRD Acquisition, L.L.C.

SECURED PARTY:                              Prime Medical Operating, Inc.

                                    By: /s/ Cheryl Williams

                                    Printed Name: Cheryl Williams

                                    Title: Vice President



                                                                    EXHIBIT 12

                  PRIME MEDICAL SERVICES, INC. AND SUBSIDIARIES
                COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
        FOR THE YEARS ENDED DECEMBER 31, 1999, 1998, 1997, 1996 and 1995

<TABLE>
<S>                                           <C>             <C>            <C>             <C>            <C>
                                                                       Years Ended December 31,
                                                 1999            1998           1997            1996           1995
                                              ------------    ------------   ------------    ------------   ------------

Income before income taxes
     and after minority interests                 $24,471         $18,171        $20,651         $10,957        $ 8,090

Undistributed equity income                          (583)           (102)          (408)              -           (299)

Minority interest income of subsidiaries
     with fixed charges                             3,726           1,823          6,074           7,000              -
                                              ------------    ------------   ------------    ------------   ------------

Adjusted earnings                                  27,614          19,892         26,317          17,957          7,791
                                              ------------    ------------   ------------    ------------   ------------

Interest on debt                                    9,408           8,469          7,477           5,977          1,231

Debt issuance costs                                   566           4,978            360           2,735              -
                                              ------------    ------------   ------------    ------------   ------------

Total fixed charges                                 9,974          13,447          7,837           8,712          1,231
                                              ------------    ------------   ------------    ------------   ------------

Total available earnings
     before fixed charges                         $37,588         $33,339        $34,154         $26,669        $ 9,022
                                              ============    ============   ============    ============   ============

Ratio                                                 3.8             2.5            4.4             3.1            7.3
                                              ============    ============   ============    ============   ============
</TABLE>






                                                                    EXHIBIT 21.1
                  SUBSIDIARIES OF PRIME MEDICAL SERVICES, INC.
                              AS OF MARCH 27, 2000


Name of Subsidiary                                      State of Incorporation
(doing business as)                                        or Organization
- -------------------                                     ----------------------
Prime Medical Operating, Inc.                           Delaware

Prime Management, Inc.                                  Nevada

Prime Cardiac Rehabilitation Services, Inc.             Delaware

Prime Diagnostic Services, Inc.                         Delaware

Prime Lithotripsy Services, Inc.                        New York
  (Reston Lithotripsy)

Prime Kidney Stone Treatment, Inc.                      New Jersey
  (Indiana Lithotripsy, West
   Virginia Lithotripsy)

Prime Diagnostic Corp. of Florida                       Delaware

Prime Lithotripter Operations, Inc.                     New York
  (Tennessee Valley Lithotripter,
   Alabama Lithotripsy)

Prime Practice Management, Inc.                         New York

R.R. Litho, Inc.                                        Delaware

Ohio Litho, Inc.                                        Delaware

Alabama Renal Stone Institute, Inc.                     Alabama

Sun Medical Technologies, Inc.                          California

Sun Acquisition, Inc.                                   California

Lithotripters, Inc.                                     North Carolina

FastStart, Inc.                                         North Carolina

National Lithotripters Association, Inc.                North Carolina

Prostatherapies, Inc                                    Delaware

MedTech Investments, Inc.                               North Carolina

Executive Medical Enterprises, Inc.                     Delaware

Texas Litho, Inc.                                       Delaware

Prime/BDR Acquisition, L.L.C.                           Delaware

Prime/BDEC Acquisition, L.L.C.                          Delaware

Horizon Vision Center, Inc.                             Nevada

California I Prostatherapy, LP                          California

North Carolina Prostatherapy, LP                        North Carolina

Texas 1 Prostatherapy, LP                               Texas


<PAGE>

Ohio Mobile Lithotripter, Ltd.                          Ohio

Ohio Mobile Lithotripter II, Ltd.                       Ohio

ARKLATX Mobile Lithotripter, LP                         Louisiana
  (Kidney Stone Center of Louisiana)

TENN-GA Stone Group Two, LP                             Tennessee

Southern California Stone Center, L.L.C.                California

AK Associates, L.L.C.                                   Texas

Metro Atlanta Stonebusters, GP                          Georgia

Kidney Stone Center of South Florida, LC                Florida

Mobile Kidney Stone Centers, Ltd.                       California

Mobile Kidney Stone Centers II, Ltd.                    California

Mobile Kidney Stone Centers III, Ltd.                   California

Northern California Lithotripsy Associates              California

Northern California Kidney Stone Center, Ltd.           California

Lithotripsy Institute of Northern California            California

Fayetteville Lithotripters Limited Partnership -
  Arizona I                                             Arizona

Fayetteville Lithotripters Limited Partnership -
  Arkansas I                                            Arkansas

San Diego Lithotripters Limited Partnership             California

California Lithotripters Limited Partnership - II, LP   California

California Lithotripters Limited Partnership - III, LP  California

California Lithotripters Limited Partnership - IV, LP   California

California Lithotripsy Joint Venture                    California

Florida Lithotripsy Limited Partnership I               Florida

Indiana Lithotripsy Limited Partnership I               Indiana

Pacific Medical Limited Partnership                     Hawaii

Las Vegas Lithotripters Limited Partnership             Nevada

Fayetteville Lithotripters Limited Partnership -
  Louisiana I                                           Louisiana

Louisiana Lithotripsy Investment Limited Partnership    Louisiana

Montana Lithotripsy Limited Partnership I               Montana

Mountain Lithotripsy Limited Partnership I              Colorado


<PAGE>

Mountain Lithotripsy GP                                 Colorado

Fayetteville Lithotripters Limited Partnership -
  South Carolina I                                      South Carolina

Fayetteville Lithotripters Limited Partnership -
  South Carolina II                                     South Carolina

Tennessee Lithotripters Limited Partnership I           Tennessee

Texas Lithotripsy Limited Partnership I                 Texas

Texas Lithotripsy Limited Partnership III               Texas

Texas Lithotripsy Limited Partnership V                 Texas

Texas Lithotripsy Limited Partnership VI                Texas

Texas Lithotripsy Limited Partnership VII               Texas

Texas Lithotripsy Joint Venture, L.L.C.                 Texas

Fayetteville Lithotripters Limited Partnership -
  Utah I                                                Utah

Fayetteville Lithotripters Limited Partnership -
  Virginia I                                            Virginia

Pacific Lithotripsy GP                                  California

Great Lakes Lithotripsy Partnership, LP                 Wisconsin

Big Sky Urological Services, LP                         Montana

Wyoming Urological Services Ltd. Partnership            Wyoming

Washington Urological Services, L.L.C.                  Washington

Kentucky I Lithotripsy, L.L.C.                          Kentucky


                                                                 EXHIBIT 23.1


                          INDEPENDENT AUDITORS' CONSENT
              ----------------------------------------------------


     We consent to  incorporation  by reference in the  registration  statements
(No.  33-70478 and  333-62245) on Form S-8 and (No.  333-12893 and 333-47621) on
Form S-3 of Prime  Medical  Services,  Inc.  of our report  dated March 6, 2000,
relating to the consolidated balance sheets of Prime Medical Services,  Inc. and
subsidiaries  as of  December  31, 1999 and 1998,  and the related  consolidated
statements of income, stockholders' equity, and cash flows for each of the years
in the three-year  period ended  December 31, 1999,  which report appears in the
Annual  Report on Form 10-K of Prime Medical  Services,  Inc. for the year ended
December 31, 1999.


/s/ KPMG LLP
- --------------------------
Austin, Texas
March 27, 2000

<TABLE> <S> <C>


<ARTICLE>                     5
<LEGEND>
This schedule contains summary financial information extracted from the
December 31, 1999 Form 10-K and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<MULTIPLIER>                                   1,000

<S>                            <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>               DEC-31-1999
<PERIOD-START>                  JAN-01-1999
<PERIOD-END>                    DEC-31-1999
<CASH>                          20,064
<SECURITIES>                     4,120
<RECEIVABLES>                   23,273
<ALLOWANCES>                       244
<INVENTORY>                      3,676
<CURRENT-ASSETS>                58,012
<PP&E>                          44,220
<DEPRECIATION>                  25,567
<TOTAL-ASSETS>                 246,826
<CURRENT-LIABILITIES>           20,493
<BONDS>                              0
                0
                          0
<COMMON>                           194
<OTHER-SE>                      87,655
<TOTAL-LIABILITY-AND-EQUITY>   246,826
<SALES>                              0
<TOTAL-REVENUES>               112,174
<CGS>                                0
<TOTAL-COSTS>                   44,939
<OTHER-EXPENSES>                10,848
<LOSS-PROVISION>                     0
<INTEREST-EXPENSE>               9,408
<INCOME-PRETAX>                 24,471
<INCOME-TAX>                     9,432
<INCOME-CONTINUING>             15,039
<DISCONTINUED>                       0
<EXTRAORDINARY>                      0
<CHANGES>                            0
<NET-INCOME>                    15,039
<EPS-BASIC>                     0.89
<EPS-DILUTED>                   0.88


</TABLE>


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